Four stroke outboard cylinder head rebuild

[@GreenCandleMakerPete]

Hi Stu, I have been watching all your videos for a while now and i would like to say a massive Thank you!!!! I have a Honda 75hp outboard, a few trips back heading back into Jervis Bay after a trip to the banks the heat sensor alarm went off and the motor went into limp mode. i noticed no water coming from the tel tail! I managed to get it back tot he ramp and got home. That's when i noticed all the things wrong with it. It had been serviced 2 years in a row by a local marine mechanic in Mittagong (where i live in the Southern Highlands). It turned out he had charged me for replacing the water pump impeller 2 years in a row and i really don't think he actually did the job as when i removed the leg for the first time myself and opened the the water pump i noticed the impeller had 2 veins snapped off!! I watched your videos and replaced it, plus the base plate and put it back together. I then started to investigate further and noticed water in the gearbox oil, it was milky. So i had to strip the gearbox out and reseal it, pressure tested and everything came up great! I changed the engine oil which looked horrible given it had been "serviced" every year. I also replaced the thermostat at this time. Still no joy, worked great with the earmuffs on, but next water test proved it still had a problem, it overheated again only 500m from the boat ramp. So i put a call out on Facebook on a well known game fishing page and everyone recommended a guy just outside of Sydney. I took the boat to him and told him all i had done to the boat. I told him i had been watching your videos and they were great, he actually said, Ohhh no not Danger Marine!! I said what are you talking about? he said Dangar Marine is known as Danger Marine. To which i quickly defended your channel as i would never have done the work i did had i not watched your videos. Anyway after $660 with him , told me the problem was sorted, he told me he cut the back of thermostat out so it was constantly running water through the head and it shouldn't overheat again!! I asked him why he did what seemed to be a band aid solution instead of finding the actual cause? He said cause if this doesn't fix it, its a head gasket which meant $3500 for a rebuild. Next water test, it overheated again!! i was getting pretty pissed off by this stage! So I set out and purchased the Service Manual for my outboard and watched all your videos, I ended up pulling the head off myself, had the head machined and all the valves re-seated (it was included in the head reconditioning, so why not??) they told me one of the exhaust valves was stuffed, so this was swapped out. Pressure tested fine.Also during this process i found one of the impeller veins that snapped off stuck in the water jacket!! ( I couldn't find the second one anywhere) I put the head back together and it fired up first go! So far so good. I took it down to the Shaolhaven river and dropped it in. Did 23nm without it skipping a beat. After all this i will never pay another person to service my outboards. Sorry for the long message here, i just wanted to convey this journey i have been on for the last few months, but its all fixed and running smoothly once again due to your expert videos knowledge. thanks once again!! Forever grateful Pete :)

[@DangarMarine]

Hey Pete, it's great to hear that you got your motor up and running, well done! The story you tell seems to be all too common. I can only think that it has to do with marine mechanics not being as tightly regulated as the automotive industry. It sounds very much like your original mechanic did practically nothing those two years, and at $660 to cut the back out of a thermostat I can see the really "danger marine" is the danger of getting ripped off. It's funny you should mention finding the impeller blade as I have been thinking of doing a video on that very soon. It is such a classic situation - pump is toast, put a new one in an still overheats due to the broken blades blocking the water. Unfortunately sometimes pulling the head off is the only way to get them out, so part of that video would be about not getting into that situation in the first place. You've done really well getting it running yourself, and I am really glad I was able to help you in my own small way. Enjoy your time on the water, Jervis Bay and the Shoalhaven River are fantastic waterways. Oh, and thanks for sticking up for my channel. :)

[@jnewts1]

Let this be a lesson in the nature of modern business , if you want something done properly " YOU MUST DO IT YOURSELF " . I would NEVER trust a Mechanic with my engines as they're my engines and not his/hers ! To pay another human to look after YOUR shit is just asking for trouble ! especially "STEALERSHIPS" .

[@jnewts1]

OH , and keep up the great work Stu , I really enjoy watching your vids . You obviously have integrity as a tech so you can exclude yourself from my recent rant !!

[@emmanuelgaviero5669]

Done! I've got the black Dangar Marine one. Thanks again for the helps!!

[@Fireship1]

Nice job rebuilding the head Stu. That tip for adjusting the valve clearances was a good one!

[@DangarMarine]

Thanks Jack. I was pleased when Arnie said that, I would never of thought of it. That motor is due back this week to re-check the valve clearances after a week of running so it will be interesting to see where they are at.

[@gstep51]

Really good video. Brought back some memories of building engines for racing when I was a kid in high school. That was many, many years ago. Keep up the great work.

[@DangarMarine]

Thanks Greg. I'd love to have a track car project to work on one day, maybe even a rally car, but somehow I think that is going to have to wait until retirement...

[@Athfos]

Hey Stu, cool to hear the locusts in the bg doing the wave! They do the wave through the whole colony which can go for hundreds of km’s. Good video.

[@DangarMarine]

Thanks mate. In some ways they are the bane of filming in Sydney, but I also like the fact that they are the sound of summer in many ways. Interesting to hear about the fact that they are triggers each other to make noise like a Mexican wave, I actually never knew that. Fun fact! :)

[@Athfos]

Dangar Marine Yes they are a pain especially where there are edits. You can sometimes disguise the audio cuts by recording a heap of atmos at your shooting location and then run it behind the other audio tracks at a low level. Anyhow keep on shooting, it’s the content and the story we love.

[@paullevasseur8454]

Living your own life is just as important (if not more so) as posting YT videos. No apologies necessary IMHO. Thanks for taking the time to make these videos. BTW, I was looking at buying a valve spring compressor recently but hadn't seen this type in use before. It looks to be much easier to operate than the lever clamp type.

[@DangarMarine]

Thanks Paul. It is tricky to manage everything that needs to get done in the week and I appreciate your understanding. I think all different types of compressors have their strengths and weaknesses. I like the fact that these are easy to control and move small amounts if needed.

[@zhillic]

Nice and informative video. This engine is in good hands! I can imagine working fulltime and trying to film in-depth repairs and projects can be a challenge, hopefully things even out after some time.

[@DangarMarine]

Thanks Fredrik. :) Time is tight, add some study and family into the equation and it does get nuts.

[@coopw101]

All that intake of knowledge left me exhausted. Peace and be safe out there. ✌🖒

[@DangarMarine]

Ha! Love your work Coop. ;)

[@michaelschmaltz7415]

Thanks for the great video. You and the useful information that you provided saved me a boat load of $!

[@bwagenberg]

Hi Stu. Not sure where to put some GREAT NEW video ideas. 1. Jet Outboards instead of propellers. Why are they not popular? Your pros and cons. 2. Zig-zagging a large heavy boat at top speed to get it on plane, when trimming isn't helping. Thanks. Really enjoying and learning from every video. Just discovered your motorcycle series.

[@DangarMarine]

Good ideas Bruce, we use the zig-zag method on our fire barge all the time.

[@jimbogasoline2042]

Great job Stu! I've never messed with valves before, only the cover which unfortunately Nissan decided it was a bright idea to use a plastic valve cover which eventually shrinks from heat and allows oil to go into the spark plug wells and gives some violent misfiring! Some parts should NEVER be made of plastic. Now I see why Nissan is cheaper than Toyota...I guess you truly get what you pay for!!

[@DangarMarine]

Thanks Jim. When plastic distorts it can be a real nightmare, great from a corrosion point of view but no so great from a heat point of view some times. :)

[@matthewcone6251]

Lol Love your videos. I'm doing the same thing on a 225 Honda right now as well.

[@DangarMarine]

Thanks mate. Good luck with the job. :)

[@jamesharkness1058]

This was very helpful!

[@dnixon1974dn]

great video pal.

[@DangarMarine]

Thanks mate. :)

[@Scotty3ist]

Great Video mate. -jack

[@DangarMarine]

Thanks Jack!

[@user-nt8xv1ns7w]

A true artist, beautiful kenetic sculpture your building Stu. Are there clear plexiglass engine covers? Be nice to look at, you know the way super cars have clear engine covers for their creations. If you get hungry on the job, locust are tasty roasted with a bit of honey. Full belly and no noise. They go well with a cold one, or two. Cheers, thanks again for the show Stu.

[@DangarMarine]

Hey Andrew, even if the full cowling wasn't clear, at least a clear valve cover would be cool. They do say as the world gets more populated that eating insects is going to be the way to go. :)

[@ianmoone2359]

Can I ask if you installed new valve stem guides below the valve stem seals?

[@Nass1986]

Beautiful

[@johncurrie8068]

Another brilliant video :-)

[@DangarMarine]

Thanks John. :)

[@grassjunky3705]

What was that you said you coated each side of head gasket with?

[@grassjunky3705]

Is there a video of pulling this head off?

[@CSJiGSaW08]

Do you have a video on removing the head, then the power head?I have a BF130, possible issue with the valves or the piston. My cylinder 3 has 75 PSI compression. Other cylinders are 185, 150, 150. Cylinder 3 had the spark plug tip bent down. I pull the injector plug and motor does not stall. On all 3 others they stall.

[@CSJiGSaW08]

Found 2 cracks on head block. It was between cylinders 2 and 3. So you recommend the valve clearance to be max limit based on service manual? Usually they are range between numbers.

[@lynch006]

Hi. Doing same job at the moment. Would you have torque specs for the head bolts

[@grassjunky3705]

Do these headbutts need oiled before torque?

[@DennisFredrickson-e3u]

Need to change head gasket on a BF50A Honda. Can it be done without removing the cam shaft and valves. In other words can I access the head bolts.

[@funluvinjay]

I love your videos i have a 25 hp with broken cam can you remove just the cam with out removing the head or separateing the power head

[@streetbobheaven4068]

question- if you were just replace just a set of intake valves do you have to cut the new seats or just install?

[@Alx28516]

Hello Dangar marine oil dripping out of exhaust tube on same engine? Any help?

[@luisjosearellanes753]

Cuantas libras de torque lleva el cabezote

[@jamesflanagan8359]

Hi what are the torque settings on camshaft and the head bazl BF50hp

[@melstevens588]

HinStu I have a 2000 BF40A it's sat for 3 yrs. I'm worried cylinder walls will be dry .What should I do prior to start up? Thanks

[@jackpatteeuw9244]

Very unusual valve/valve seat design ! I have never seen an aluminum head WITHOUT a valve set insert. Ask the machine shop if there a special angles required on the seat and the valves themselves.

[@DangarMarine]

I'm hoping to do some filming at the engineer's one day. My understanding is that the angle he cuts on the valves and seats is very specific, but I'm not sure what it is.

[@jackpatteeuw9244]

I guess the real point is, it is NOT a classic "3 angle" grind ! You are lucky to have a good machine shop near by who pays attention to details !

[@CSJiGSaW08]

can you reuse the springs

[@gyorgyimre7774]

is it possible that a newly rebulit head, and valve steam seals are leaking a little bit with new valves built in?

[@locknloadbitch]

In this case, i guess it's possible, but the valves will take their right "shapes" eventually. That being said, there are tools that exist to shape the valves perfectly into their places, using that specil tool (cant remember the name) and some sort of abravise material.

[@prwillms]

Yes it is. When rebuilding the head you should check the guides for wear by using a dial gauge and rocking the valve stem side to side. There is a tolerance that the manufacture should have as a max. If that guide is over the max tolerance, There will be a blowby even if there is a new valve guide seal. Cheers

[@gyorgyimre7774]

thnx;) good to know

[@prwillms]

Hi Locknloadbitch, The procedure is called lapping the valve seat. Where the valve rests in the head. the seats can be ground with a valve seat grinding tool. If there is not much damage to the seat the valve can be faced. Grinding is a good way to make sure you have a good angle for the seating of the valve. It is a good practice to lap the valve to the seat to get a good seal. Easy to do. Lapping compound comes in a can one side has coarse and the other has fine. The tool to use is a suction cup on a dowel. It turns the valve back and forth "cutting" the valve face to the valve seat in the head. This cut line will also show where the "seat" will rest on the valve. If it is to the outer edge of the valve face, you could need a new valve seat put into the head. Cheers.

[@CSJiGSaW08]

Usually the head assembly you can get new without the cam shaft and other components but it does include the guides installed.

[@arnefourie118]

Hi, do you maybe have a the torque specs for cylinder head? Busy working on mine and can't find the specs anywhere. Thanks

[@jacksonjarbas6183]

Muito bom

[@DangarMarine]

Thank you!

[@damodoesall6240]

That head was nice and clean ! How far does the head and valve corrosion have to go before you say it needs replacing.?

[@DangarMarine]

Yes, the engineer cleans it up nicely before doing the machining. Generally I leave the bin or keep decision to him as he will know whether there was enough metal left to machine it flat and he will also pressure test the head once he is finished which is really the ultimate decider. The great thing is if it isn't usable he will return it without charging which is very nice.

[@chuckcull5674]

Strange that there are no cam bearings on these engines. I would surely use a liberal amount of assembly lube on the cam prior to installation to prevent spalling.

[@markwatkins1974]

I found two of them collets in my sump when I emptied the oil and the second cylinder isn’t working? Any ideas what would cause this and is it a case of take apart and reinstall the collets? Thanks

[@DangarMarine]

If they haven’t broken I would say it was caused by incorrect installation. You might want to install new ones to be on the safe side.

[@markwatkins1974]

@@DangarMarine thank you for the reply, I am now very confused I took the rocker cover off to check and all 6 springs appear to have the collets attached. However second cylinder isn’t firing as when I take the spark ht lead off there is no change in engine compared to the other two leads when I take them off. Have switched all spark plugs around and they all work. :-/ also the spark plug in the second cylinder was very black

[@roughas100]

Funny how different manufacturers design things like rocker shafts , was doing the valve clearances on my Tohatsu 50hp 3cyl last week , it has 6 valves too like the Honda but only a single rocker shaft , saves a bit weight only having 1 shaft , can't see what advantages there are having 2 rocker shafts for a single camshaft engine? I do get some intermittent ticking noise on the Tohatsu, suspect it might be something to do with the rocker arms sliding up or down on the rocker shaft , maybe those thin springs are too weak?

[@outboard_usk]

can I contact you?

[@DangarMarine]

Comments here is the best way.

[@daleharris960]

Hi Stu, I am currently working on a 10hp Honda that has broken the cam pulley. My question is: will the valves have perhaps hit the top of the pistons and bent them, or are the pistons far enough away from the valves( interference or non - interference) Your help will be highly appreciated- regards Dale Harris

[@graymodeler]

"That thing got a Hemi?" Looks like it. Valves can be larger due to the angle and the gas flow on the split overlap period is straighter in and out.

[@DangarMarine]

Yep, having the flow across the valves can be great to aid scavenging.

[@crispernator]

Great video mate , i am fairly lucky as my father was very mechanical and showed me a lot as i was growing up which has served me well over the years and also some of the tools i didnt have to buy . a question with the pittting on the back side of the valves exhaust i think they were would it have paid to replace them or just leave them ? anyway very well explained and a good video .

[@DangarMarine]

I think it if the sealing edge of the valve is machined or lapped to good condition then the pitting isn't such an issue. When my friend got this boat back he said it felt like we'd turboed it it ran so much better. :)

[@trumpet1783]

the engine has been standing for 4 years and has 550 hours..the problem was in the white wire, but I solved that and the engine started. I started it for a few days for 10-15 seconds and everything was fine and now it won't anymore..the pump works but there is no spark..it gives me the error 2 4 CMP sensor..bought a new one and the same thing..I doubt if the chain can skip? I would like to check that but I don't know how? what positions should be on the FLYWHEEL COVER and on the hole when the CMP sensor is removed? Th

[@jaytol1]

Have a suzuki df70 2003 4 stroke compression test all good bottom cylinder has best compression but getting water in oil and into cylinder 4 any advice on what's my problem??

[@DangarMarine]

Most likely a blown head gasket.

[@jaytol1]

@@DangarMarine wouldn't i lose compression?

[@vetterfellow]

In an emergency can the number one piston be used to set top dead center?. If you gently put a screwdriver or wooden dowel into the plug hole, turn the engine till piston is fully extended then a hair turn into the beginning of the down stroke. just curious. Thanks My Friend; for the problems that go along with making a master piece video... Angelo.

[@DangarMarine]

Hey Angelo, you can get a rough idea that way, but as you approach TDC, the change in the piston travel is quite small compared to the rotation of the crank so it isn't super accurate. As you say though, it is a way that can be used if need be. The other problem with outboards like this is that the spark plugs come in at a very shallow angle to the head of the piston which makes things even harder.

[@ronpowell2373]

Angelo, at TDC and BDC the crank turns at the same rate however there is about a 5 degree area of the crank rotation where the piston does not move much. The only way to get a TDC is by using a dial gauge resting on top of the piston. Once you get the dial gauge reading highest piston level you then roll the crank back and forth until you get same reading - say 10 thou - each side of the high point. You them mark the crank with a texta. The middle of those two marks is going to be your crank's TDC. Harder to describe than do. Your method can have you out by 5-10 degrees if the plug holes are not exactly in the centre of the cylinder head. On the Honda head in the video you would be lucky to get closer than about 5 degrees to TDC.

[@ronmccarroll9588]

I have a 40 horsepower Suzuki four stroke The intake valve have no clearance exhaust valve have way too much clearance I have no compression on the bottom cylinder it's exhausting out got any ideas or film

[@danieletognozzi7641]

Hi Stu! This has been so informative, thanks a lot! I am a total newbie and I am trying to fix my 5hp Honda outboard. We cleaned the carburetor and fixed the fuel line, and we got to the point in which it would start and idle properly, and run low for about one hour without big issues. The problem comes when we run full throttle. If it´s cold it would hold the power for a while, but as soon as the temperature goes up, it would lose suddenly strength and sometimes turn off. I got to the conclusion that the valve clearance must be adjusted, but I fear there could be some corrosion on the valves. Another very strange thing is that since a couple of days it would turn on ONLY with the choke off. (??) Do you think that issue could be also related to the valves? or is it just the carburetor butterfly that is once again sealed? Would be worth trying do the job with no experience? Thanks for your time. d

[@matthewmoses4222]

Hi Stu, no need to lap the valve faces with paste into the seats?

[@richardcranium5839]

they say its no longer needed i always do to check my contact pattern and margins

[@DangarMarine]

Hi Matthew, when I did the Yamaha I lapped the valves, but as this head had been off to the engineer, he had cut the valves and the valve seats. I'd really like to go and do some filming at the engineers shop to get the full story, but my understanding is that he cuts the valves to and angle very slightly different to the seats and then as they operate they bed themselves in to make a better seat than lapping will. (This is why the valve clearance closes up slightly in the first week of operation).

[@firefalcon100]

Ah that's good to know the details on that because my Honda shop manual for the BF 15-20 says to lap the valves if it doesn't seat well. The devil is in the details. Great videos, learned tons from you sir. In fact i wouldn't have considered doing a complete rebuild on that Honda 15 i found and pulled up from the briny deep without the videos, keep it up!!

[@alexanderrivas6998]

Enjoy watching your videos very informative. Would you be able to do a video on a water pump R&R on a 4Stroke Yamaha just interested in seeing your technique on the woodruff key. What's your Instagram as well would definitely follow you know what your doing.

[@DangarMarine]

VERY old video, but it might help you kzbin.info/www/bejne/f6KxnGeGbpmqhdU Instagram is DangarStu.

[@michaelbenton9308]

Hi I was wondering if you could point me into the right direction with my outboard I have a 50hp Honda I believe it's a 06 had a tapping noise in motor they clunk stopped run any idea's. Anything is much appreciated

[@deant6627]

Hi Stu, ive just brought a brand new head and valves (not pre assembled) for my ride on mower, just wondering if the valves still need to be lapped or are they good to go as is, considering they are new? Cheers.

[@DangarMarine]

It really depends on how they are cut, but if in doubt I would lap them, even if it is only to see how well they mate to each other. You will see very quickly whether there is a good contact surface between the two or not. If so, stop and cleanup, if not, keep going until there is.

[@latrex]

Hi, can you tell where I can get free repair manual for Mercury 100, efi, 2008 ? I need bolt torque for head installing

[@DangarMarine]

You can usually find a reasonably cheap one on readmanual.com or tradebit.com

[@latrex]

thanks !

[@flaviodinizgasparlontrofla6769]

Por favor, quantos kg é o aperto da cabeça do cilindro do honda 20 hp ?

[@boatsandhoes3397]

Hey mate after some advice looking at buying a yamaha 75hp enduro apparently its been fully rebuilt and what not has a couple hundred hours use on it compression readings around the 95 to 100 mark all even i was expecting it to be higher but was told fatory compression for this model is 105psi is there any way you could check that for me cheers

[@DangarMarine]

I believe those motors do have quite low compression so it does sounds about right. Also, be aware that most compression testers aren't super accurate so you are mostly looking for all cylinders being equal.

[@boatsandhoes3397]

Yeah thanks do you know where i could check what factory compression is for it

[@DangarMarine]

You'd have to locate the service manual for it. Try readmanual.com or tradebit.com

[@ronpowell2373]

Interesting the head has undrilled fuel injector holes - maybe Honda's next upgrade ? I know the engine is a repurposed car engine and in the car role it is fuel injected.

[@DangarMarine]

Hey Ron, this outboard was the very last year before they went fuel injected on the 40s.

[@walidamers9703]

The Yamaha motor has 50 dives in water for 5 hours and can be maintained at a depth not more than 3 meters

[@tahirnomanghouri5762]

Hello sir I want to learn how to du tapit can you send me any video thanks

[@DangarMarine]

Sorry, I forgot to post that link! kzbin.info/www/bejne/l4eliIF3ndhmjrc

[@normanboyes4983]

Hi Stu thank you for posting this interesting video. I was intrigued that you did not lap the valves to their seats using carborundum paste and a dolly. Is that the specific advice for this particular engine, or is that a Honda thing? I have not so fond memories of doing this on a 1.5 MW - V16 diesel generator (some years ago) with 4 valves per head so 64 valve seats and you have to be uber scrupulous to clean out the last remnants of carborundum from the seats and valves and the in fact the whole head. IIRC the whole lapping process took 3 long 12 hour days and about the same again to assemble all the heads prior to fitting them to the blocks

[@DangarMarine]

Hi Norman, when I did the Yamaha I lapped the valves, but as this head had been off to the engineer, he had cut the valves and the valve seats. I'd really like to go and do some filming at the engineers shop to get the full story, but my understanding is that he cuts the valves to and angle very slightly different to the seats and then as they operate they bed themselves in to make a better seat than lapping will. (This is why the valve clearance closes up slightly in the first week of operation).

[@lentmain]

Is that background noise cicadas..???

[@DangarMarine]

Yes, Cicadas.

[@knudpedersen3915]

Hi and thx for your great videos - I have watched and learned:-) Please allow me to ask a question as no one have been able to answer before.... I`ve got this motor (tohatsu ifs 30 Hp) witch is having some troubles as it runs varm, and the warning system starts. I've it for 1 year and the problem have increased, and now it runs varm af 2.5 minutes in full speed. I`ve clean alle the hoses and canals I can get to. I've switched the thermostat and the impeller and the gaskets and it did not solve t problem. You seem to have a point when it comes to outboards, so maybe you or others can give me a hint? I brought the motor used a year ago.. See the video here: kzbin.info/www/bejne/Z3WtfoeknJp_e7M Kind regards from Denmark:-)

[@DangarMarine]

The next two things I would check is that it is actually getting warm by testing the sensor and using an infrared thermometer. I would then also consider than it may be a blown head gasket causing the overheating.

[@kermets]

Stu I just purchased a BF50 for a parts engine and it had a broken spring which caused the valve to hit the piston damaging both......have you every heard of these engines breaking valve springs ? check out picture 8 www.trademe.co.nz/Browse/Listing.aspx?id=1745427227 cheers Brett

[@DangarMarine]

I haven't heard of the them breaking springs but it can happen due to a minor defect in the metal. I have seen some of them quite rusty from a blown head gasket letting water into the oil which can also contribute to them breaking.