How to change fuel filters and bleed air in a Yanmar marine diesel

[@christophermcguinness468]

So following up on my last comment I replaced the fuel filters today and had a couple things I thought I would share. First, bleeding the lines with the butterfly valve seemed nearly impossible. My primary fuel filter was huge and the butter fly valve is really slow. My starter and solenoid are tucked in pretty deep so I ended up clipping two long wires on each end of the start switch in the cockpit and attaching them to another switch I kept near me so I could run the starter by just bypassing the start switch. That worked great. Second, I ended up having to bleed the lines all the way to the individual fuel injectors because I had trouble starting up after bleeding them to the point where Dr. Spelunk did stopped. Basically I had to bleed them at the primary fuel filter, secondary, the inlet to the fuel pump or fuel injectors (the thing where one fuel line goes in and three come out), and then finally the individual fuel injectors. Using the decompression valve trick to bleed the lines made things way easier. And it wasn't too difficult once I had a switch setup. Don't forget to stop the water intake before running the starter. It sounds like that could mess things up. Good luck everybody. Thanks Dr. Spelunk!

[@spelunkerd]

Excellent follow up advice, thanks for taking the time to stop back and help others.

[@snakeplisken4278]

Thanks guys, very interesting. Why should water intake be shutoff? Also, I have a 12v fuel pump in-line next to my primary racor filter on my Yanmar 3hm35f. I have not used it but my understanding is that one can turn on the ignition key (to provide power), then this fuel pump has a toggle switch to at least prime the primary filter. Am I correct in assuming one can try to start the engine without bleeding each injector? Then if it does not, bleed each of them as well? Lastly where does one get one of those by-pass starter switches? (Model?)

[@santiagoferrari1973]

0:50 so diesel just explodes?! No heat source?

[@spelunkerd]

@@snakeplisken4278 It looks like I missed your remark, which sometimes happens in subthreads like this one. Common practice in these engines is to to shut off salt water intake when you crank without starting. This is done to prevent the salt water from flooding the exhaust manifold and possibly causing salt water to reflux into a cylinder, damaging a piston. More detail in the video, but essentially when pistons don't push much air, water can splash backwards from a rusted exhaust elbow. I like your design with a 12V fuel pump. Yup, that would be useful for bleeding, and you wouldn't need the hotwire switch I used. You can make your own hotwire switch, or buy a cheap one from any automotive parts store. If you make it yourself, don't cheap out on the wires or switch quality, since even the signal side of the starter circuit carries enough current to melt inadequate hardware. You can often get by with not bleeding all the way to each injector, I stopped after bleeding to the fuel regulator.

[@tarheelace]

Santiago Ferrari No spark. There will be heat from the compression. My lay understanding is that it’s this heat that causes the combustion of the fuel-air mixture, but maybe an engineer would phrase it differently.

[@billypeake6475]

people like who who take the time to shoot, edit, upload these videos are the unsung heros of today. Thank you

[@mikel442]

I just bought a sailboat with a Yanmar diesel and your videos are invaluable to maintaining my engine correctly. Thank you so much!!

[@daneulekowski929]

Going to look at a sailboat with a 2gm, this was a very well made video. Thank you for putting it together.

[@joyceycasas9479]

Thank you! This is awesomely helpful. So clearly explained and shown, no filler, just good advice. You know your stuff and are generous to take the effort to make these videos and to share your knowledge.

[@thelenwilliams]

Great instruction by an obviously extremely erudite gentleman. The most thorough video I've seen on KZbin. Thank you!

[@jacqueslemon]

Just great! I'm about to buy a boat with a 2 cylinder Yanmar. Videos of this quality just improve so much our confidence in fixing things by our own.

[@robsalthouse4911]

Excellent. I’m an engineer just learning about diesels and I found this to be very informative and well presented.

[@AMaverickBrother]

Another tip I'll add... I just installed a new filter just like the one you show in this video and I also didn't have spare fuel. Mine would not pick up fuel at all straight out of the box. But putting a little bit of diesel onto the seal at the end of the pump actually made mine start working and really made the pumping go a LOT faster.

[@MikeJohnson0]

I came back a year later to refresh my memory on all the steps, a google search lead me to the same video. Thanks again!

[@MichelleGianni]

Thanks to your video I was able to replace both my fuel filters (Racor + primary) in my new to me sailboat with a Yanmar 3GM30F right after I bled the last screw on the engine block it started right up!! Thank you....!!!

[@traveltoonsbymp]

Looking forward to more of your videos. So clearly explained. Although I didn't bleed air or changed filters, I was able to follow your directions on my own engine. I could find the lines and valves etc.. even though things are not exactly the same on my engine Yanmar 3GM30F 1990. So grateful. Things are making sense.

[@pauleenwardbrown]

Very helpful and detailed video. I made a list of all the steps (we knew we had air in our system) even did screen grabs so when we were at the boat we could follow your instructions with pictures! Brilliant!!! it worked. Interestingly, when we got to the high pressure pump, we released the decompression valves, cranked the motor, the valves flipped closed by themselves and the engine started. What a relief - thank you for the video - an excellent help!

[@apackwestbound5946]

After watching some of these video for the second or third time I am even more impressed with your productions. In my opinion you do an amazing job presenting an overview of what we are looking at and explaining the various parts of the system before you go into the specific subject matter (fuel filter replacement, raw water pump removal and rebuild). Something you mentioned in passing is contrary to what I have been taught, that has to do with pre-filling the secondary fuel filter with "fresh" diesel after a filter change. I have been cautioned not to do this because these secondary filters are designed to remove very small contaminants, smaller than the human eye can detect which is limited to approximately 40 microns. Consequently the fuel may look very clean to our eyes, but still have contaminants that can cause havoc, 3-4 microns, in the extremely small tolerances within the fuel injector pump and injectors themselves. The problem is that the contaminants causing the most damage are too small to see so the visual check is ineffective. So filling the secondary fuel filter bypasses the secondary fuel filter with that fuel which is introduced unfiltered and becomes a point of contamination. Prefilling the primary fuel filter is fine, even a good idea, but not the secondary fuel filter. Did I misunderstand what you said, or do you have contrary information? The methodology I have been taught during a filter change is to prefill the new primary fuel filter with "clean & fresh" diesel, change out the secondary fuel filter then use the lift pump to prime through the secondary fuel filter, filtering the fuel through the smaller filter and continuing up to the jerk or rotary pump using the lift pump. The lift pump will not prime through the fuel injector pump, so the injectors themselves will need/may need to be bled as the engine is turned over. Your thoughts????? -Respectfully

[@spelunkerd]

Yes, I agree, exactly. I don't go through the extra effort of prefilling for that very reason, though I suppose one could manually filter fuel. Thanks for the kind feedback!

[@IrregularPineapples]

This was amazing. Thank you so much. Just bought a sailboat with a small old yanmar and this is really helping me out.

[@8hazmat]

Excited to find the cooling system. I have the same engine and your videos are invaluable for shortening my learning curve. Thank you so much for making this available in a very easy to follow format.

[@kalleklp7291]

These videos just get better and better... :) The more I watch the more I learn about this engine without even having a spanner in the hand.

[@ronm3380]

Excellent video! This was a real eye opener about diesel engines. We just bought a sailboat with a 2 cyl Yanmar and need to get familiar with how everything works. A big thank you!

[@captratty2167]

I have only recently come across your episodes and find them clear, informative and very relevant to the faithful GM series. One trick to make bleeding the fuel system easier than wriggling the lift pump for ever and a day is to fit a rubber outboard motor fuel priming bulb (about $20 for a good one) into the line between the tank and the primary (low pressure) filter. It will usually prime all the way through the primary filter to the high pressure filter on the engine. So far (touch wood) I have never had to crack the injectors to fully bleed the system after changing both filters. Just be sure to run the engine under load (ie in gear with some rpm on) at the dock for a good 20 minutes after any fuel system work to be absolutely sure that no air is lurking waiting to stall your engine at an inconvenient time (ask me how I learned this the hard way...).

[@dansaniti3651]

What an excellent description. The best I have seen yet on KZbin. Thanks again

[@spelunkerd]

What a kind remark, thank you.

[@travisgill3568]

A huge thumb-up for putting this video together. Your video gave us the confidence to do a filter change and bleed with no problems. We also learned more about our Yanmar diesel. Thank you!! Cheers, Travis & Chantil Gill S/V HANNAH 2003 Hunter 356

[@spelunkerd]

Hey, man, what a kind remark, thank you! I've put together a playlist of Yanmar videos on my channel, and I hope to add to that over the next year with some cooling system videos. It's gratifying to learn that a few fellow sailors find them useful. Dave Equinox Victoria BC

[@moriver3857]

Great presentation. I'm in the final touches of fully rebuilding my Yanmar 3GMF and will go through most of this initially before installing the engine since I only have access from front and back, and a small door to check oil and change the secondary fuel filter. Well done.

[@TheAngelhard]

Thanks a lot for this great video and the good and easy understandable explanation. That saved my day when I didn't get my Yanmar back to work after changing the Diesel filter. Thank you so much!

[@charlesm903]

Great video production with perfect content needed by a new owner of a vessel with a 3YM30. Ready now to change the filters and save the $275 my marina charged last year to change the two filters! Thanks Dave

[@spelunkerd]

You're welcome, I'm glad it helped, Charles. I've been meaning to do another one on cooling systems, I hope you follow along. Please stop back and let us know how the fuel filter change worked out for you.

[@alexandernetherton321]

Just want to join those that appreciate this video an extraordinary resource. Thanks. About to begin on a a 2QM15!

[@briansmobile1]

Great video! I know how hard it can be to get the shots you did. This topic and the physics behind it can be elusive and you nailed that too!

[@spelunkerd]

What a kind remark, thank you Brian.

[@briansmobile1]

I've got a 4x4x4 forklift with a no start that I bought. The lift pump failed and I fitted an electric one. When I did that, it wouldn't purge... ever. I relocated closer to the tank and lower. The pump never pressurizes in the new location and the engine almost starts, but doesn't. I'm SO CLOSE, but not there yet.

[@jamessalkind]

Thanks to you I fixed my engine after I ran out of fuel. I couldn't get the last bleed screw to turn without stripping it, but the engine started anyway.

[@fortress2666]

Thank you very much for the video! We ended up in basicly middle of nowhere with engine throubles and your video was very helpful!

[@Mark_KE8YCV]

Excellent video! I'm replacing an ancient fuel-water separator on my boat. I have a 20HP Beta Marine Kubota on a Catalina 30. This year it developed an fuel leak after the electric pump and after I fixed that I sow how shoddy the workmanship was in cobbling together aftermarket components in the rest of the fuel system. Going to re-do it all. So this video, although for a different engine, was very helpful.

[@philiphewitt3985]

Excellent video. I watch it every time before filter changes.

[@AdventuresofHappyOurs]

Thanks for the explanation. I’m a gasser and always wanted to learn more about diesels.

[@s.v.naniola3170]

Thank you. You are really good at explaining the complexities of deissel engines. Thanks.

[@spelunkerd]

Last night I discovered a better upload codec that seems to improve HD quality significantly, with much less choppy movement and better integration of sound and video. For those who watch in HD, this should offer much better video quality for future videos. I find the pure mechanical design of these old diesel engines to be elegantly simple.

[@captlarry-3525]

quite well done. I've done a lot of these extemporaneous narration videos..where you are doing something while explaining it.. and in creep those little mal-aprops. Very few here, and none really important. Bravo !

[@spelunkerd]

Yes, you're right, too many um's at times when I could not reshoot. Thank you for overlooking those, it will be a priority to make that part better moving forward in future efforts. Only those who have tried this game before will know how hard it is to make videos, ha ha.

[@patrickbodnar]

Very well explained. Don't forget the water valve opening at the end.

[@hughburgess4168]

Beautifully explained and filmed. I turned the compression levers off to suck my fuel to the secondary fuel filter. I then turned the starter motor twice for 10 seconds, but still no fuel coming through the bleeder nut. Reluctant to try it again. I do have fuel coming through the bleeder nut at the water separation filter.

[@spelunkerd]

Some guys use a suction vacuum, similar to those used to change oil in these engines, to draw the diesel fluid up the tubing. I demonstrated how to use a suction pump in an oil change video. Fuel butterfly pumps don't do well with air in the line, because air is so compressible. When the pump creates a vacuum air can expand, rather than drawing the much more viscous diesel fluid up the tubing. The other possibility might be a problem with the diaphragm of the butterfly pump itself. I've never had one of those apart but you can rebuild them. Finally, go back and check your assumptions, verify you've got diesel in the fuel tank and you haven't left the shutoff valve closed, and you haven't left a bleed screw open on the intake side.

[@stuzman52]

I really enjoyed this video Dave and you know that engine very well. Lots of tips and how to in this video which I found interesting. And she started right up and sounded very good. Oh somebody really did a number on that fuel filter being tight there. Keep up the good work Dave! 👍👍

[@spelunkerd]

Thanks Terry!

[@johnmoore3859]

Really excellent video. Clear and concise with superb camera work. Thank you for sharing the knowledge and also for taking the time to make the video.

[@andreruegg9490]

Thanks a lot, very informative. I feel confident to do it myself tomorrow.

[@brendanmcc]

Great help! Thanks. I hadn't done this in a couple of years so this was a concise refresher! Grateful!!

[@luisroebuck4354]

Thank you for sharing .berry uninteresting topics, and very clear, fuel is the most common problem in any combustion system and is been ignore in the boating entusiast

[@threebattles]

Great video. I am about to attempt this myself on my boat. This was well done and very useful.

[@jeffc6038]

Great info and thanks for taking the time to put these video togetter great quality and sound

[@AMaverickBrother]

I've referenced this video several times and I've gotten a lot of help from it. Thank you!

[@christophermcguinness468]

Thanks so much Spelunkerd. Your videos are great. After watching this I'm going to give it a try and replace my fuel filters. We'll see if I'm brave enough (or impatient enough) to try the decompression valve trick to bleed the air out. Thanks!

[@businessexpansionstrategie4015]

Good video, showing step by step the sequence of bleeding air from the fuel system. I have tried the same sequence however my engine is a 2GM only 2 cylinders but have noticed that it has one more filter besides the water separator filter and the fuel filter before going into the high press pump. That filter I mentioned I have not been able to open it so I bypassed it and keep the sequence, when I go to the high press pump I opened the bleed screw and a lot of air and bubbles came out with pressure in it. I started the engine with the decompression valves up, run it for 10 seconds and only diesel then was coming out from the high press bleed nut. I tightened it and put the decompression levers down, went and started the engine and it started. It stayed a good 10 minutes and slowly died again, tried to crank the engine and it didn't start. I went back did the same sequence and found more air in the high press pump, did the same process as before to bleed air out and started the engine again. It run for another 10 minutes or less and stalled it didn't stay running for more than 10 minutes. What do you think it may be the problem? Thank you for the info.

[@spelunkerd]

Air is leaking in, from somewhere. I'd wonder if the seal on one of your filters is not seating correctly, and would start by getting a set of seals for each filter canister and replace them all. Remember to coat them with diesel or oil to allow them to seat well. If that effort fails, gee, I don't know. Maybe air is leaking past the threads on one of your bleed screws. I suppose one could pressure test the system and look for an air leak with soapy water, I've never done that in a fuel system. Or you could close the intake valve and apply vacuum with a vacuum gauge to see if the line can maintain vacuum. You might hear a hissing sound as air passes by an area. I suppose also the butterfly valve has a diaphragm that could be torn, I've never seen that happen. Please stop by after the problem is solved, and let us all know what you found.

[@businessexpansionstrategie4015]

@@spelunkerd Hi Mr Spelunkerd, I tried what you suggested, changed the filter gasket and put a new one making sure it was sitting well. Tightened a little bit more the bleed screw on the fuel filter, I put a little bit of Teflon tape making sure the bleed hole in the screw was free. I bled the air on the high pressure valve, some bubbles came out from the bleed screw. Then I tightened the screw and started the engine, it took a bit but it started. I noticed the throttle cable is lose and doesn't stay in high RMP only medium or low, if I put it in high rpm the throttle cable goes down on the rpm by itself. I was hoping the engine would stay at least in mid or low rpm, however like last week the engine slowly stalled till it shut down. Tried again bleeding the air 3 times same process and every time it stayed for 7 minutes approximately and shut down. I checked the water separator and let it drain, the diesel came out with dirt and water inside, drained 2 more times to get the bad diesel out and it came more dirt and water from the separator. I wonder if the reason of of the engine shutting down after a few minutes is the contamination of the diesel going through the fuel system and creating air bubbles even after the system was bled. Could that be possible? Do you have a video on how to clean the diesel tank? Any suggestions will be helpful. Thank you.

[@spelunkerd]

@@businessexpansionstrategie4015 Gee, I don't know. Yup, dirty fuel is often the culprit, you could bypass the fuel in the tank entirely, running from a container of clean fuel, and that would test for a failed tank check valve, too. If it fails with that you could put a fuel pressure gauge on one of the distal bleed screws to be sure your fuel pump is delivering adequate fuel volume. Failing that you could arrange for a compression test, valve adjustment, and probably removal and cleaning of injectors. This is getting beyond typical DIY maintenance. Specifically to test compression you need an adapter that fits into the injector hole, since these Yanmars don't have glow plugs.

[@LittleGuitarConcert]

Thanks so much for this. I really appreciate the clear and thoughtful explanation - very helpful! A Racor and fuel filter change is my project for this week. If you don't mind, I also have a question but I haven't been able to find any related discussion: I recently replaced the mixing elbow assembly on my 3GM30F. Previously, I had noticed some white steam emanating from the exhaust, (especially at higher RPMs) as well as a noticeable discoloration building up on the transom after only an hour or two of motoring. Since the replacement of the exhaust elbow, both the steam and the discoloration issues seem to have now been resolved. However, I have also noticed that the sound of the exhaust as it exits the back of the boat is significantly louder than it was before? Prior to replacing the mixing elbow, she seemed to purr right along vs. now sounding more like a tractor pull. I do have the Vetus Waterlock system installed - Anything else I should be checking? As I mentioned, I can't seem to find anything on-line related to this issue and I'm wondering if the louder exhaust volume is merely the result of having unimpeded flow through the new mixing elbow ( the old elbow was pretty clogged)? I'd love to have your thoughts... Cheers!

[@spelunkerd]

Safety is always the first consideration, I'd be carefully looking for an exhaust leak, especially around the elbow and exhaust manifold. It wouldn't be uncommon to have a bad fit between the new elbow and the exhaust manifold. Remember to look closely for a crack in the exhaust manifold, they often crack from overheating. If you don't already have one, I would upgrade to ABYC standard by installing a battery powered carbon monoxide detector, positioned somewhere near the floor. Next on the list is the waterlock muffler, check to be sure it is filling and working properly, and that the necessary second loop is present at the exit point for the waterlock muffler. Downstream of the muffler, another common point of exhaust leak is the water drain from a hot water heat exchanger, if you have one installed. They tend to rust out. If you don't find anything downstream, then then next thing I would consider is whether your salt water flow is adequate. My sea cock is one of those old style screw type valves and if it is not screwed all the way out I get restricted flow. It may be time to inspect and swap out your impeller, and if any fins are missing then an inspection of the heat exchanger is next. Sometimes pump activity is poor when you first restart after working on the system until air pockets are cleared. If you find a cause, please stop by and let us all know what was found.

[@LittleGuitarConcert]

@@spelunkerd Thanks so much for your quick reply. I will pick up a CO monitor today - Now that you've suggested it, it makes me nervous having been without one! I also have a new impeller which I will install as well. I have looked as carefully as possible, but have not found any leaks or cracks around the elbow itself or manifold. I did have a suspicion that the waterlock muffler may not be filling correctly, but didn't really know how to check this. Is there a recommended protocol? I'm not sure there is a 2nd loop installed between the waterlock and exit - I need to look again, but I remember it being a fairly straight shot out to the back of the boat. There is a vented loop before the elbow. Cheers -Thanks for your advice!

[@congsan3528]

Well made video. Love it. Learned a lot. I guess I have to think twice before making the purchase of a catamaran sailboat. Way too much work. Thanks.

[@spelunkerd]

Oh yeah, I know! Strangely, the biggest expense every year is for marina parking, which is an eye opening fact (even worse for a cat). The most painstaking maintenance issue by far is the annual haul out, which means paint and sanding, with enough time on the hard to repair deeper problems and let undercoats of paint dry. You can count on a week of maintenance time every year, hoping weather cooperates to allow you to paint without rain complicating the game. Comparing that to the option to rent a boat for a week a year, you'd come out better off renting (or, even better, tag along with a sailing friend, ha ha).

[@beckywhalley4258]

Thank you, this video is so helpful as it has clear instruction, really helped me with my marine engineering, engine assessment writeup

[@stanleybradley5513]

Great video, it really helps demystify how the engine operates!

[@garryn123]

Very interesting and gave me confidence to do the filter changes on my boat myself...keep up the good work!

[@telepix212]

Really helpful for understanding my 2GMF. Thank you!

[@SailingwithMaury]

Good job, great video. About to launch my rebuild sailboat with a brand new y2m15 which was installed a long time ago by someone else. I am mostly a stranger to motors so this is super helpful.

[@soundisfunction]

Great video, I'm going to replace my fuel lines on a similar model Yanmar so this is very informative.

[@elcheapo5302]

Another informative and educational video. Thank you for sharing. Looking forward to the water pump video! Oh, and congratulations on the first successful use of a strap wrench ever! :)

[@spelunkerd]

Thanks, I know what you mean about the strap wrench conundrum.

[@annlisbethpedersen2140]

just seen your vlog, thank you so much, it was very helpfull and informative. Great job & wel done, Greeting from Denmark

[@spelunkerd]

You're welcome, thanks for stopping by!

[@dacarthaGian]

Awesome video! Following your video just got me out the boatyard! Thanks for sharing it!

[@Clipperdefender]

Excellent video. Great explanations. Very informative. Thanks for making this video.

[@nadowayne]

Great video 👏

[@timlamarre8680]

Excellent video. Than you for posting.

[@paulchanonu3174]

Congratulations It is very interesting. I try to change myself diesel filters on my yanmar 4jh2te next week. Thanks

[@karlberardi4351]

I’ve bypassed my mechanical lift pump with an electric fuel pump from NAPA it simplifies bleeding. The elec. fuel pump is 17 yrs old,it’s going strong and costs very little, about half the cost of the rebuild kit for the mechanical lift pump.

[@etothelij]

Where's that video at? 😅

[@tomscott3476]

Great instruction. Did everything right and then today I pulled the shutoff 1 inch out and got a start. Seems the shutoff cable was not set correctly.

[@spelunkerd]

Good point, I'm sure your remark will help others who stop by. That's a common observation, another boat I have sailed on had the same issue.

[@spelunkerd]

_Erratum_I wish we still had the old KZbin annotations, that allowed an author to modify a written remark. At 13:27 the written remark does not apply in these little Yanmar engines. Specifically the Yanmar decompression lever shifts the exhaust valve for that cylinder open a little, resulting in no compression, and shunting a mix of unburnt fuel and air into the exhaust. It wouldn't be good for emissions or catalytic convertors, but these engines don't have cats.

[@victoriastreet8919]

Great series. If the shutoff lever is actuated then no diesel is injected while cranking. I find operation of the lift pump lever is adequate for filling/bleeding the points beyond the lift pump but you must rotate away from the high part of the cam lobe else the pump's travel is already engaged. The pump spring is heavy, about 2lb force on the lever. You have the option of using your Racor 200 priming pump for this task. For FWC versions of these engines, the bleeder bolt on the fuel injection inlet is very hard to get to. You can tackle it better with a wrench custom bent with a sharp 90deg at the box end. Then the open end of that wrench is easily torqued with another tool.

[@miltonlopez3482]

Hi thanks it wass stock rust y got it to loose free i open the back and side and work it out i pull the fuel pump out to so lots of work but is moving great the tip is the springs

[@oceancrossingutopia]

Thanks so much. This is hugely helpful.

[@jakobwal]

Hi I think all of you that are having problem using the feed pump manual feed is using it wrong. When you push the lever, 80% of the stroke is just picking up slack, the last 20% is what does the pumping. When you feel resistance in the lever, try pushing it a bit further. You will feel what I can best describe as pumping feeling. I have no problem fillinf both my fuel filters from empty to full in under a minute using only the manual feed.

[@spelunkerd]

Good point, although the basic design is similar, we all need to be familiar with how our own pump works. Even when purged of air, my butterfly lever has a hard end stop so I don't get the response yours does, but your remark will be worth remembering for others who stop by. If mine were to do that I would wonder if the pump is resting on a high point of the cam lever, and I might choose to rotate the crank a little to make pumping more efficient. There is a dramatic difference in how these pumps perform if the line is not purged of air, which explains why air in the fuel line is a common cause of engine shutdown. If you push the lever with air in the line, the air volume expands to fill the void, rather than drawing the viscous diesel fuel upward. Energy you put into cranking the lever is absorbed by the air and the diesel moves very slowly, like trying to run in sand. Fluid won't move at all if there isn't a minimal amount of suction, which might give the impression of better response at the end of each stroke. Once the short stretch of line between the fuel filter and pump is clear of air, pumping the rest of the line is dead easy. As you say with the line clear of air you can actually feel the pump doing its job. If there was some way to design the system so that the line leading up to the pump would purge by gravity it would be much easier, but as always there are competing design interests. In any boat it is critical to have heavy parts like the fuel tank as low as possible to promote stability, so that short stretch between filter and pump is unavoidable.

[@jakobwal]

@@spelunkerd Really good point about the position of the cam! Anyway, I have a 3gm30 and recently removed the pump becuse i broke it (ruined the threads #facepalm). Figured I could share what it lookes like on the inside when you operate the manual lever. kzbin.info/www/bejne/epyQXqCrqrZ0gMU

[@darrellstreet90]

Great work with the in-depth video! Good point that these pumps are slow at pumping air. You had the option of continuing to use the primary filter's plunger pump as it could do all the downstream bleeding. Sadly, most engines don't have a compression release. A primer bulb in the line before the primary filter is a great option if the primary filter doesn't have a pump. It is much quicker than any of the 3 pumping means shown. Like many filter bowls of plastic (like yours), it doesn't meet the heat test used by UL/ABYC/USCG which may get (largely invalid) insurance scrutiny if mounted in the engine space. There are electric pumps by Facet that have both the low pressure desired and a free forward flow when off but as you say, they are electrical. They cost the same as a spare mechanical pump which can fail at the diaphragm or the check valves. A leaking diaphragm might leak fuel into the crankcase or bilge. How many years to trust them? Simple as they are, they are a risk and should probably get swapped at 500hrs/10yrs interval and keep the used one as spare or replace with electric and plug the mechanical pump's output port.

[@paulmaslen5897]

Thank you for the awesome video! My Universal 35HP needs oil and oil filter as well as fuel filter (primary and secondary) change. I hope to do the work myself and have a functioning engine after the fact! Fingers crossed!

[@DouglasBWelch]

Very helpful video. Thanks

[@MartinVanRijswijk]

Thanks for the very informative video. Really helpful

[@captainjoecatino9696]

Great video. Thank you Any videos on oil change, winterization, fuel filter change and zinc replacements on a 6LYA-STP?

[@spelunkerd]

None for that engine, though the basic principles are shared with all diesel engines. Yanmar offer repair manuals and owner manuals for free on their website; use Google with the above model number to get there with a single click. I did an oil change video, and I made a Yanmar/boating playlist on my KZbin channel. Thanks for dropping by!

[@captlarry-3525]

I am about to get a boat that has this kind of disposable fuel filter with the removable water separator... which is different than the old Racor type I know.. with a cartridge inside..or the VW diesel filter I live with everyday. So most valuable not be hunched over in the bilge.. learning by doing it wrong ! Thanks.

[@steve-i1095]

Great Video. I learned a lot, thanks. My Volvo seems to be set up a bit differently.

[@spelunkerd]

Thanks Steve! As I recall, layout is a bit different but fundamentals should be the same. We should have a look at it one day.

[@martinfossatti2848]

Hi Dave, thank you for the video, I find it very useful. I m trying to start a 3YM30 Yanmar Diesel engine that was inoperative for more than 3 years and I ve realized the problem is water on the fuel line. I'm afraid that trying to start it I ve overcranked the engine and filled the pistons with sea water, do you have any advice for this issue. Thanks in advance, Martin

[@martinfossatti2848]

Thaks for all the directions, very detailled and explicative !! I'll try this weekend and let you know.

[@tomjoad1060]

Hi! My name is Gennady, and I wrote to you about 2 years ago. Today, I started my engine, and at first I felt that it provided no push, then I saw a black liquid coming out of exhaust. And finally, the engine stopped. I tried to start it again, but it would stop after a few seconds. My engine is Yanmar 30 GM. Any ideas on what could be the problem?

[@stevewillis2112]

Nice job. Thanks. My Yanmar fuel regulator cable springs back, very annoying, won't stay at needed fuel setting, springs back to idle. Any ideas why? Thanks

[@spelunkerd]

When I replaced my cables, they slide so easily that they don't stay put at speeds just above idle, the cable control springs back to idle. This is annoying when your attention is diverted elsewhere as you leave the slip. No such problem at higher RPM. I tried tightening the screws that hold the mechanism together, which helped a little. If you find a better solution, please record it here! With time the friction inside the wire cable is slowly increasing, so it is not much of an issue any more.

[@stevewillis2112]

@@spelunkerd thanks for the response! I will keep working on it. It seems the springs inside the housing are super strong, pushing back the speed to idle. Thanks again

[@duartesousa2908]

Great video. Very helpful. Thank you.

[@personalbest849]

Thanks for the excellent and methodical instructions. I am planning to do this tomorrow and have a question. My YSM12 motor has a hand crank. Could I use this to crank the motor (with the decompression l ever off) instead of the starter motor to bleed the system? Cheers - Mark

[@spelunkerd]

Yes, this reminds me of something I saw in Africa, a hand crank to start a diesel well pump. Note that if you hand crank a diesel, there's a risk it might start, especially if those spring loaded decompression switches slip back to full compression when the engine shudders. That could be dangerous if your wrench spins out of your hand when the engine starts. Better to use a ratchet socket wrench that will allow the engine to spin faster as you pull the wrench away. Even cranking a small two cylinder diesel can be a lot of work, I don't think you'll be able to turn it fast enough or long enough to easily purge air from the fuel delivery system. I'd get a remote starter switch, they are sold at automotive stores or amazon, everywhere. Good luck!

[@MrA1582000]

Great video and explanation.

[@joewadsworth7324]

The engine’s closest bleed point used in the video, had a rubber input hose attached. Is it possible to attach the vacuum pump that many of us use to suck out engine oil, to pull diesel through the filters and hoses?

[@spelunkerd]

Yes, some do it that way.

[@michaelhodgett11]

I’ve already winterized and have just changed the oil. Is there any harm in not running the engine until spring at this point? Thanks!

[@spelunkerd]

It's probably OK. My usual strategy is to drain the carb bowl, for two reasons. First, fuel retained in the bowl tends to go stale as volatile components evaporate away, leaving varnish that can stick tiny orifices closed. Second, if the petcock is not working, when you open the carb bowl drain, it won't stop dripping, indicating it is time to clean the petcock. My routine is to add Stabil to the fuel, run it for a while to circulate it, and leave the tank full so water in air won't form dew as temp falls, causing the engine to choke out next spring. I pull the battery and keep it in a warmer garage, intermittently charging through the winter.

[@daneulekowski929]

Would it be possible to flush the diesel system with fresh diesel by attaching a clean fuel source to the fuel hose at the tank, and then pull a vacuum on the return side at the tank? Or is the return only for unspent fuel at the injectors? Trying to keep it simple, as I would like to see this motor run before purchase, boat has been on the hard for 4 years and I'm sure the fuel is nasty. Thanks for any advice

[@spelunkerd]

I agree that bad fuel is your primary concern. Most guys would flush and clean the tank in some way, and flush the line. However I don't think vacuum on the return line would draw fuel past the butterfly valve and regulator by itself. As you say you could substitute an alternate fuel source from a separate container if you want, but I don't think applying vacuum on the return line would serve any purpose.... Good luck!

[@daneulekowski929]

@@spelunkerd Thanks for your quick reply, your videos are really informative.

[@takeseverythingyouvegot]

Very helpful. Getting an old 3QM30 in my C&C 38 back into fighting condition. FYI, I used my oil suction device to suck fuel through to the small high pressure fuel filter after I changed it and the racor. Worked like a charm. Quick question. Do you adjust valves on these old Yanmars?

[@spelunkerd]

Camshaft valve clearance is mechanically adjustable, though I don't believe there is a usual maintenance schedule for valve clearance. I have not done it in my engine, yet. Good thought about your oil suction device. As long as vacuum isn't high enough to blow out the filter I assume it would be fine. Effectively the engine pumps up a vacuum anyway. Thanks for adding to the thread here!

[@brianzachary5618]

I installed an inline primer bulb like you would use on an outboard motor to bleed air on my 2gmf. The tickler on the Yanmar doesn't seam to do anything.

[@spelunkerd]

Good point. I think the combination of trapped air that expands under vacuum plus viscous diesel fuel makes it hard for those pumps to work until they can clear the air pocket. When the starter motor spins it activates that butterfly valve much faster than one can move it manually so the trapped air is cleared, after which the pump is very efficient. If the primer bulb is low down and closer to the fuel tank, it ends up pushing fuel rather than trying to suck up air bubbles. Thanks for your contribution!

[@captlarry-3525]

running a close third on the enemy list is Algae.. which can and does grow in old diesel..once it is contaminated by condensed moisture.. . moisture, dirt.. algae heaven.

[@santiagoferrari1973]

100%. Much of that dirt is either algae food, or their residue

[@rnunezc.4575]

Thank you for your videos. Have any idea why a Yammar diesel marine stalls when on low rpm and in shift to reverse or forward stalls and dies..? have checked pretty much all. We need to get rpms up to sometimes prevent stalling but very hard to dock boat with this problem etc...Any ideas would be great and will appreciate so much your reply. Thank a lot!

[@spelunkerd]

Check the simple things first, maybe consider raising idle speed with the idle adjustment screw. Bad fuel, maybe water in the fuel, fuel filters.

[@rnunezc.4575]

@@spelunkerd thank you v much, yes I am trying that especially idle rpm.

[@SoItGoesCAL34]

You have an arrow pointing to a nut that says Idle Adjust Screw when you a ralking about the cable. I'm a bit confused byt that. Thanks for the video

[@spelunkerd]

At the helm when you want more power you push the engine lever at the helm forward. The lever at the helm pulls on the regulator cable to give the engine more diesel fuel, which raises rpm. On the engine side, that regulator cable is attached to a spring loaded lever that adjusts fuel delivery (and target rpm of the governor) inside the high pressure pump. When the cable is slack, the internal spring holds the lever against the tip of the idle adjust screw, causing rpm to slow to idle speed. This means that adjusting the screw position will change idle speed. The idle adjust screw is the rusted, threaded bolt that the arrow points to at 17:36. You can see it has a slot on the end to allow adjustment with a flat blade screwdriver, after loosening the locking nut. I did a whole video on replacing both the engine stop cable and the regulator cable, so if interested you'll find more details there. I hope that helps. It's more simple than it sounds. You might (carefully) play with that cable a little while engine is running to see how rpm changes.

[@mckenziekeith7434]

After you tighten the bleeder valve on the racor, can't you just keep pumping the racor pump instead of the lift pump?

[@spelunkerd]

That's a good question, I've never done that. If the downstream screw is cracked open, it may work. I know some guys use an external pump for a faster work flow, so the butterfly pump is evidently no obstacle to flow.

[@georgecanakis1075]

Excellent video thank you

[@SteveReitzel-x2o]

I realize these posts are a bit dated now, but still a great and timely video. One question: Is there a reason you do not continue to prime the fuel system with the Racor pump? Once it fills the Racor filter, will it not continue to push fuel up through the secondary fuel filter? The Racor pump seems to have more capacity than the Yanmar butterfly pump.

[@spelunkerd]

that’s a good thought, these pumps are better at pushing liquid than air. I’ve never tried it.l

[@johnyray590]

Would there be an unintended consequence of adding a 12V fuel pump, placed upstream of the raycor, used for bleeding only?

[@spelunkerd]

Good question, short answer is I don't know. Long answer is that you already have one, by using the starter motor as shown. A dedicated pump near the bottom of the line might work a little better than the mechanical one in the engine because it would clear air and prime itself more quickly. Many outboard engines use a hand operated pump, so you might not even need the extra complexity and risk of another electrical appliance. However in the big picture I'm happy with how mine works as is. Thanks for your thoughtful remark!

[@ReachingFast]

Hey great video! I'm installing a Racor 10 micron primary and 2 micron secondary on my Hunter 466. thanks for the demo on your system. Have you any advice on sealing the hard line connection at the filter assembly? What have you found that doesn't degrade from contact with diesel? All the best Skip, Tony

[@spelunkerd]

My connections are all hoses, and I would choose line specifically designed for fuel. I haven't seen hard line connections on a boat, but old school steel fuel line connections are pretty common in motor vehicles and also brakes. Many of those have a flare design.

[@tartansailor]

If you had continued pumping fuel at the primary filter, you would not have had to use the manual pump on the engine. Use the filter pump until you hear fuel returning to the tank. The engine will start on the first crank. Cheers, Richard

[@bostonbase35]

Excellent video

[@miltonlopez3482]

hi Dave real good videos i have the same engine i just finish a valve job and i find the regulator to be not moving at all is this normal ? whit the engine of and another do i havefto bled the hig preshure pump to?

[@spelunkerd]

That regulator control should move, though I found it to be very stiff when the engine is off. With engine running it moves much more freely.

[@johnyray590]

I’ve just did all this, and what was once a dry engine, now has a slight leak at the secondary, yanmar filter. I just can’t get the O ring to set! Have you seen this before? Any suggestions? I’ve taken it off and on about 3 times, all with a drop (only when engine is running) Any tips are appreciated! Thank you,

[@spelunkerd]

Dealers say to replace O-rings at the same time, they are cheap and easy to swap out. I would get a small tray, add about 10cc of motor oil to it, then put the new O-ring right into the tray so it's coated with oil. Then check the mating surfaces for dirt and carefully slide the new seal on. In the video you saw me coat the primary filter seals using diesel rather than motor oil. Motor oil is probably better for sealing leaks, and it is probably also better for more easily getting the filter off later. You might have a tiny bit of sand or debris preventing a tight seal, it doesn't take much. Don't forget to carefully examine the mating surface, you'll probably need a mirror and a light to see it properly. A small drip of diesel out isn't too much of an issue, I've seen that before. Getting air into the system would be more concerning. Good luck! If you think of another method that works better for you, don't forget to stop back and leave notes for others who visit here.

[@darrellstreet90]

For the longest time I had a slight ooze at my secondary filter which I traced to the bleed port. The copper washer, even when annealed or replaced didn't seal. I had to polish the mating surface on the casting before that was fixed.

[@robertb7254]

When I get ready to spring commission my marine diesel should I hold down the start and stop buttons to crank the engine to build up a little oil pressure then release the stop to fire it? Should I worry about that hydrolock issue? I learning here…bear with me…

[@spelunkerd]

Those are good questions. I suppose if your engine is too quick to fire up, it might be worth considering, but I don't do that. In my engine, delayed starting after sitting for a while is the dominant problem. As you say, the biggest risk to a delayed start is salt water hydrolock in a cold engine with no glow plugs. If I don't expect the engine to start quickly, sometimes I go through the effort to turn off the salt water intake to avoid flooding the exhaust with salt water before combustion sends a dominant stream of exhaust gasses out. The most egregious error would be to close the salt water intake and then forget to open it back up quickly after starting, so bear in mind the stupid factor. An alternate option if you want to delay the start would be to hold the decompression valves open while you crank for a few seconds. That would prime fuel and oil delivery passages and accomplish the goal.

[@johnyray590]

If you don't have filtered diesel, can you fill the filters with diesel treatment?

[@spelunkerd]

I suppose it's possible, though the cleaner needs to be combustible by itself to not stall the engine when a pure dose hits the cylinders. Professional fuel injector cleaners are designed to do that in gasoline engines and I presume a similar formulation is available in a diesel form. However as you saw it was simple enough to clear the line the way I did it, and all of the fuel that made it to the injectors was filtered to 10 microns twice. If you get a speck of dirt into an injector you may need an expensive overhaul that might be avoided by being careful to filter everything that is on its way through the injectors.

[@ReachingFast]

I noticed in your video that you had steel hose connectors screwed into the assembly. How are these sealed? Are they PFTE taped, puttied or other. This is what I was referring to. Thanks for your rapid reply to my question. Kind regards Tony

[@rmhollin25]

thank you , great video and very helpful

[@spelunkerd]

You're welcome, I'm glad it helped.

[@davidfritch6954]

Great video, thanks for making it!