HOW-TO Pressure & Vacuum Test On A Chainsaw - Leak Down Test

[@jamesgingin590]

I like how you get right to the point and don't dribble on about things that don't matter. You're the best small engine mechanic on KZbin.

[@reedjose7624]

I know Im asking the wrong place but does anybody know a tool to log back into an Instagram account..? I was stupid lost the account password. I would love any tricks you can give me!

[@reedjose7624]

@Byron Kelvin I really appreciate your reply. I got to the site through google and I'm trying it out atm. Looks like it's gonna take quite some time so I will reply here later with my results.

[@reedjose7624]

@Byron Kelvin It did the trick and I now got access to my account again. Im so happy:D Thank you so much you saved my account :D

[@byronkelvin912]

@Reed Jose Happy to help xD

[@num1booger]

DONY, I KNOW WERE ALL HUMAN AND HAVE OPINIONS, I DO NOT UNDERSTAND WHY ANYONE WOULD LEAVE A DIS LIKE (THUMBS DOWN)EVERYTHING IVE WATCHED FROM YOU ALL YOUR KNOWLEDGE IS WONDERFUL FOR US DO IT YOUR SELF FIX IT GUYS.BLESSINGS TO YOU AND ALL READING THISSTEVE IN BEAUMONT CALLY

[@donyboy73]

+Steve Hoover jealousy causes people to do that, also other insecure shop owners who don't want people to fix their own stuff

[@garyronan5568]

donyboy73 Or A guy that sells new chainsaws!!

[@thomasgronek6469]

Big Guy; I was thinking the same thing. If the thumbs down is clicked, a piece of constructive criticism should be left out of courtesy, and for the sake of improving skills and knowledge.

[@seansysig]

A very clear & concise troubleshooting video that can solve a saws inability to run! Best Small Engine Repair You Tube Channel!

[@donyboy73]

+Sean Signer thanks Sean!

[@da8ish1]

great video! thanks. 6:10 in i think that vacuum may be in inches

[@neilphilip2320]

On your vacuum test, the gauge was reading inches of mercury which is not the same as psi - but a useful video as vacuum leaks can destroy 2-stroke engines fairly quickly.

[@seanbrenton55]

Thanks to this video, I did a rudimentary press/vac test with a big veterinary syringe on my 1978 Stihl 031 and was able to rule out the crank seals. ended up being a deteriorated impulse line. Saved me tons of time and money. Thanks, Don!

[@ralstondaley6448]

Your so professional donyboy73

[@Wjones450]

I have used this way of pressure/vac testing for a few years now and it does indeed work very well. like he said tho just make sure your connections to the pump are solid! Also works great for carburetor work

[@clubdetennisdolbeau-mistas5971]

A REAL PRO. It's great to see you performing as you do. Thanks for all those vids and keep up the good work.

[@SteveRobReviews]

Nice tip Donny . Since I already have an automotive smoke machine I have found it works great as well in testing for all sorts of leaks on small engines too.

[@donyboy73]

+Steve Rob that would be nice to have!

[@Fireship1]

+donyboy73 you can make one with common materials such as a paint can, a tiki torch wick and some nichrome wire. Google it and or look on eBay for completed ones and kits to make your own. Not expensive at all, work just as good!

[@danielh4995]

Man I am glad I read this comment! I hadnt thought of doing that to test for leaks but I will now. I actually have an 038 Mag II that wont idle after a port, polish, and refresh. I suspect the cylinder to crankcase seal is the issue but that will be a great way to confirm.

[@musketbal]

It was impossible to find anything similar to what Donny uses for the pressure test. What I did was take a large bottle cork (from hardware store) so it fit snug in the bellow with approximately 1/2" of the cork exposed . I then drilled a hole in the cork after the fit check and placed a piece of fuel line through the cork leaving enough exposed to allow for the vacuum pump to be attached. I also covered the top and area around the fuel line with black permatex RTV for a good seal. The bottom was also done in the same fashion. I then used a small hose clamp to keep it secure when installed into the bellow. Not too fancy, but if you can't find the adapter Donny uses, I think this should work.

[@lornaandy969]

Thanks Dony, first class as usual. What were the symptoms with this saw??

[@drewthornton4684]

the old wizard 998 thanks im new to this small engine thing last year i got a whipper snipper fixed and running thanks to don

[@sglas7102]

Last comment, so true. Your explanations and step by step are spot on! Bravo

[@TedSailAwayCost]

Thank you very much Donny , I believe you are the best instructor on small engines . I firmly believe you will be a great teacher in a technical training school in the future . Once again you have solved my chain saw problems and now running like clockwork . Kind regards Ted , west Australia

[@earllister2513]

Dony, your videos are extremely helpful! I enjoy the detail and attention you give. I have learned a lot from you! Keep putting out videos !

[@gtb4]

One of the best channels I’ve seen. Thank you!😊

[@bird474]

I'd like to see you do a leak down test on a snow blower/lawn mower! : )

[@isalenxs]

Where do you get the rubber pieses thank you

[@carlmiller1034]

Great video Don! Thanks for the thorough detail on how to trouble shoot with the use of the pressure and vacuum tests.

[@donyboy73]

+James David thanks for watching david

[@allenletizia321]

Nice job . I think got try that. It might be adjustment on carb Mine will start with spray spray starting fluid . Thanks showing that.

[@__oK__]

I think I'll have test my 3 STIHL 010 AV because they all have same symptoms.

[@phillipkramer6638]

Pressure I was told almost always is the head gasket when its set up like you had it. Didn't know that. Thanks as always. Your videos are the best and well worth subscribing.

[@ButchElrod]

I'm interested in that adapter, or an idea for a home made adapter, to connect the pump to the bellows.

[@davidschliebe246]

Don I just vac-press tested a stihl ms390. It's got great pressure test results. HOWEVER it won't pass the vacuum test. What could cause this result.???

[@gilbertvelazquez1254]

Thank You Dony like all your videos

[@donyboy73]

+Gil Velazquez thanks Gil!

[@leec12]

Excellent presentation. Timely because I just bought a Mityvac to test my saws that I work on.

[@coolbluelights]

Crank seals are very important in a 2 stroke

[@billtattersfield2895]

Great content thanks

[@Norwaywildlife]

I like this very good instruction and cool you go that deep as here on the machine repair. Thak you allot ! Keep up the good work. Very helpful for us that has a passion about making small engines run as they are intended to do. I just like to restore them...just for fun.

[@snort455]

gracias

[@RussellBooth1977]

I did with an air compressor with a Stihl hedge trimmer I rebuilt, one crank seal leaked but I went to the bearing shop & bought 2 of the same sized seals for $15 AUD. The machine had other problems as well but it had no more leaks after that.

[@phillipkramer6638]

Can I use that attacher with the carb on and test the carb at the same time as long as I keep the pressure lower. Thanks for you videos which so far are the best ive seen quality.

[@smittys19daytona]

it is sad that we live in such a disposable world where 100 an hour labor from a shop, high dollar parts from sthil push it quickly to the need to trash it which makes this information that much more valuable.forced to by import parts, bought a saw ran ok but is basically junk after seeing the scored piston , but I'm really enjoying going through these videos just realized the seals were bad ,lots of oil in the clutch was just going to do the piston now I know the cause thanks great channel

[@Chris-Fennimore]

Good video Don. I got a couple 028s that I replaced crank seals on, but still got a leak somewhere. I'll try the pressure test on them.

[@GHULAMABBAS-bs4hy]

Please make the video of MS 382 chain saw trouble shooting

[@Ducktruckful]

Don I was wandering after you run this test,if you can do a upper cyl leak down test with piston up to see if rings are bad, like on a 4 stroke.... thanks again great job

[@shakirratheriok1857]

Sir what happens if chainsaw leaks it bogs down under load....thanks this is most important issue in chanies saws..

[@jamesmullins3219]

excellent video. Removing the seal employs a knowledgeable mechanics trick... you may consider adding that to your next version of this clop. Great editing. Thanks Dony for another good video

[@donyboy73]

+James Mullins thanks, yes I will make a seal removal video

[@davidmech2956]

Thank you

[@wtbm123]

Good video

[@donyboy73]

+wtbm123 thanks

[@RG-wy1ol]

Thanks for making this video did you make your own parts to to the pressure test?

[@johnkosheluk1041]

I am a stihl tech I have the same vac tester I made a tool to keep the case at 8 psi ot can be a pain to keep pumping the tester

[@davidthorne6796]

Sweet drill out and pick grip and rip on that seal !!!! That's a sweet time saver, Sir! Thanks again

[@rickforsty9410]

Very informative!!

[@travischandler272]

did you replace the seal with out splitting the case ?

[@donyboy73]

+travis chandler yes I just popped it out from the surface

[@lewishodge4935]

Great video; would like to see how you replaced seal without disassembling engine.

[@happyrecluse2849]

Lewis,did you see the hole he drilled in the old seal?

[@warrenscott9990]

thanks Don! nice job

[@donyboy73]

+Warren Scott thanks

[@yveskc1]

Thanks for sharing!

[@phoenixtimber4343]

I like your style. Usually I get bored watching videos because there is too much fluff. Your videos are excellent.

[@jbbolts]

hey would that tester work on carbs as well? thanks really appreciate your videos

[@leehotspur9679]

Well presented Donny Thanks for sharing Cheers from NZ

[@donyboy73]

Glad you enjoyed it

[@geojor]

good one, dony...

[@lfts2010]

Dude! Fantastic informative video! Thank you

[@friendshipyu]

thorough advice

[@MrSparkums]

I have an 038 magnum Ii. I did the same but blocked from behind the carb covering the impulse line. Holds 6psi for over 5 min at bdc, both vac and press, but compression test from the spark plug leaks out, wont hold compression when cranking. what am I doing wrong? Great vids thanks!

[@MrSparkums]

No scoring on the cylinder, and it does run. Im thinking its piston rings.. meh!

[@toddc4d]

@@MrSparkums did you ever figure out what was causing low compression, I have no scoring and changed rings and still low compression, thanks todd

[@MrSparkums]

@@toddc4d MI It wound up being the rings.. I would invest in a mighty vac, and make some block off plates. No way to eliminate Gasket or seal leaks without a p/v test.. I wound up selling it for a pretty penny.. Instant regret...

[@geneballay9590]

Very nice video

[@donyboy73]

+Gene Ballay thanks

[@gclaper1234]

Hi I have a question can this be done through to spark plug hole. Thanks Glenn

[@miguelcicora6861]

I hook my compression tester on 2 different chainsaws 1 working and the other one doesn't both have the same reading 30psi. Any thoughts 💭.

[@mcmaster22]

Another Great video as always. Thanks again Dony for sharing with us.

[@donyboy73]

+mcmaster22 you're welcome, have a good weekend

[@Fireship1]

Great video. I wonder if this would work on a two stroke outboard. I'm guessing it would.

[@willf5768]

Great video thanks for sharing 🙂👍

[@pyrog.c.c89]

How do you take out the seal.

[@RG-wy1ol]

Thanks man for making this video very helpful 👍🏽

[@semco72057]

That is nice to know and I didn't know about that going wrong on the saws.

[@madlybackwards5611]

So might this seal cause the saw to leak oil from the bottom. Or would there be a seal for the chain oiler?? Thanks awesome helpful vids i cant afford to keep throwing away tools!

[@fourbyfourer]

Thanks for this well explained very informative video.

[@garyhoward3123]

Will the mighty vac work as well as the walbro pressure tester you show in another video, for carbs?

[@mooregoodink6971]

What would cause a small two-stroke engine to generate crankcase vacuum yet virtually no pressure? Am I doing something wrong? The chainsaw is a Craftsman and probably forty years old (similar to a Poulan micro saw, I believe) and with all the apertures plugged, as you advise, (sheet metal plates with cork gaskets as interfaces) my MV 8500 Mityvac displays about 2psi on the gauge (indicating a massive air leak) but no bubbles. When switched to vacuum, the test equipment quickly generates 7 in Hg. The reason I'm investigating is because the machine runs erratically when warm and has a vibration in its handle, indicating crankcase bearings and seals could be worn and leaking. Thank you for your excellent series of videos.

[@jorgeortega1709]

Another great video! Can you show us how to replace the crankshaft and/or flywheel seals on a chainsaw in the near future?

[@jorgeortega1709]

Sorry meant clutch not crankshaft

[@nickdonato4488]

My small engine has a problem I start it and then after like a couple seconds it dies can u make a video on how to fix it

[@shawnmrfixitlee6478]

Great vid Don , Thanks !!

[@patrickrusca5950]

thanks for doing this video. very clear and helpful. all the best :)

[@John-viheavyequipment]

hi there iv beening working on a husky 266 i can not get it to start iv replaced fuel line and filter and it has spark was running a year ago what should i do? wont fire at all even with a little fuel put in carb

[@jayhiz3514]

Thanks agin great video.

[@GHULAMABBAS-bs4hy]

Very good service Knowledge

[@lewishodge4935]

Dony: I'm waiting on my order of a MityVac vac/pressure gauge to test my saws. I'm wondering if this would make things easier? I propose using a rubber stopper in the intake boot. It might have to be held in place under pressure, but may work very well under vacuum. Then perform test through the impulse line. What do you think?

[@almo19]

Amazing video, thank you Dony! Your videos are sooo helpful! I have a Stihl BG55 blower that I want to leak down test. Do you know how I could do that without a bellows? Is there some kind of adapter I can use to add pressure or vacuum through the spark plug hole. Thank you!!!!

[@douglas747wct]

Hi, great video. I have a MS361 and the same adaptor you used for the leak down test. What did you fabricate to use it with the handle/gas tank assy removed? It makes the procedure a lot simpler! Thanks

[@tonyaiello6463]

I just love your videos!

[@clauslundberg9224]

Great video. Do you have a part number for the Still fitting attached to the bellow?

[@snw56]

I too, would like to know where this Stihl adapter can be found. Anyone know where?

[@deckrower]

You can find it on eBay. I don't know the actual part number.

[@alejandrovier2958]

This pump can be used in carburetors?

[@donyboy73]

Yes

[@lauraw3923]

Why do the oil seals go bad? Could it be linked to overheating, lean running or dirt ingestion?

[@donyboy73]

wear and tear and if a bearing is worn it also causes the seal to wear as well thus causing an air leak

[@mrbill9454]

Hey Donny. Do you have a link to a pres/vac tester kit you would recommend? I need to get one!

[@johnkosheluk1041]

Plus you have to be careful when you put the pump down it doesn't relice the presher the lever is on the bottom I think bad ida of the miti

[@ciprianmarin5182]

where did you get that thing that attaches to the intake manifold

[@hiphopman72]

Solid video thanks

[@ice25781]

tHANKS Dony. One more inlightful vid. Great work. Have a nice day.

[@donyboy73]

+ice25781 thanks

[@newyota1]

Should the piston be at bottom or top dead center

[@willywgb]

It doesn't matter the position of the piston.

[@stanwilson7566]

Could you show how to replacing the seal?

[@willywgb]

How to Replace a Seal. Using a set of calipers, measure the deepth of the old seal. Carefully drill a small hole in the side of the seal centered between the ID and OD. Install a self tapping screw into this hole. Be very careful not to drill or install the screw to deep or you will damage the crankshaft bearing. Using either a slide hammer or channel locks, grab the head of the screw and pull the seal out. Be very careful not to damage the running surface of the crankshaft or the seal bore. Clean everything up and install the new seal with the appropriate seal driver or a deep socket. Make sure to install the new seal to the same deepth as the old one. A little oil on the crankshaft surface and a light smear of silicon in the seal bore. Make sure to preform a second pressure/vacuum test. It's a good idea to give the crankshaft a turn when pressure testing older seals.

[@RussellBooth1977]

I'm going to have to do something like that to my Briggs & Stratton 3.5 HP engine this weekend. I lapped the valves in today & I still get a misfire at idle speed,I noticed that the top of the engine is dirty so I want to check if the top crankshaft oil seal is sucking in air & blowing out crankcase vapours. The valves did need a lap job because the exhaust valve was just carboned up so it was all black whereas the inlet valves face was eccentric. I want to plug up the PCV tube & blow air into the oil filler hole through a piece of rubber hose to pressurise the crankcase then to use soapy water to see if there are any bubbles present,which would indicate that it has an air leak.

[@abigailgabriel2348]

Hey Donny I don't know how to ask you a question but I'll ask here trying to get a respond. I just started my generator last snow storm and it was very loud and sparks were coming out of the exhaust. It's about a 10 year old generator maybe older. Need some advice

[@eddiewilson4291]

+abigail gabriel I recently watched one of Donny's videos that showed the same thing on an engine. The exhaust valve was stuck, or out of adjustment. Look for this video and I think it will help.

[@genehensley767]

good video. Don been waiting for that one for a long time how did you remove the seals that would be my only question thanks a lot

[@donyboy73]

+gene hensley I used a sharp pic and hammer

[@joew9392]

Just did a pressure test on my 029, started at about 8 hg on the vacuum and pressure and it held it for about 2 or three minutes before dropping down to about 5. Don't know if it's acceptable or not but might also be my homemade equipment..

[@raymondcampbell2346]

Good info Don. where did you get your Mighty Vac leak vacum leak tester?

[@donyboy73]

+Raymond Campbell got the pump from an auto parts store, you can get it on amazon

[@hollissmith5467]

where can i find crank seals for a 28 boss

[@alfonzo907]

I did not realize that vacuum or pressure had anything to do with an engine's ability to perform right . Good show old chap !!!!!!!!!!!!!! ----Ernest E. Johnson

[@colin8532]

Excellent video, I didn't know any of this. Thank you very much :)

[@patrickrusca5950]

hey Colin. how's life?! hope u are well.

[@hotbikerguy1988]

If I had an air leak like that one would it run my saw too lean to make it overheat? I’ve gone through 2 top ends now on my Stihl ms 440 and I don’t know why!!!!!! I haven’t checked the crankshaft seals yet

[@donyboy73]

yes it would, on the 440 check the intake boot, it might be cracked

[@kencourtright3636]

AWSOME informative video !

[@nygardenguru]

Does the piston have to be at TDC seems like there is a chance the piston could block the air intake and access to the bottom end of the crankcase