How To Pressure & Vacuum Test A 2 Stroke Engine

[@VintageEngineRepairs]

If this video helped you, please consider clicking on the THANKS button above to support my channel 🙌

[@markluxton3402]

What is Permatex #3? Nothing comes up on Permatex nor Amazon for that name.

[@markluxton3402]

What is Permatex number 3? Not on Permatex web site nor Amazon???

[@billbyrd9845]

I'm a 77y/o retired motorcycle mechanic, and I could not have done better in explaining these things. Well done!

[@VintageEngineRepairs]

Very kind thank you Bill!

[@wxyzxdll]

Great to see an Englishman who not only knows his trade, but speaks the Queens English well. No umms, yeahs, ya knows, awesomes, and all most importantly , no likes. Thats competence. Excellent explanations given as you go along. A pleasure to listen to you.

[@VintageEngineRepairs]

I have gotten much better in my newer videos, you won’t hear a single “um” or “ahh”. Unfortunately in my earlier content I was less aware of how bad it sounds, so they slipped in, but I appreciate the kind words even though you are being a bit too generous to me haha, thank you :)

[@ProSaw70]

Good video Tom. Vacuum is measured in inches of Mercury. InHg. 👍🏼

[@savage22bolt32]

remember the mercury filled Carb Stix?

[@garymcmullin2292]

you sure have it right, well presented. You are undoubtedly a class A mechanic as you pay attention to detail and proceed in an orderly manner. Disciplined mechanic. Thanks for a valuable info video.

[@VintageEngineRepairs]

Thanks for the kind words, I’m glad you enjoyed it!

[@Jorge-de2ny]

Totally agree

[@THEMOWERMEDIC1]

Greetings from texas, brilliant demonstration! Liked and subscribed!

[@klydolph2]

I replaced the crank seals, put on a carb kit on my approx 15 years old Stihl MS250. Replaced all fuel lines and filters. Now it runs much worse than when I started. It wont idle properly. I have tried adjusting the high and low jets and the idle screw for hours. It idles fine after starting - then when I use it for a minute and it goes back to idle it will stop. I turn up the idle speed, but then the idle will be obviously too high. I ordered a pressure and vacuum tester today. Thanks a lot for the video.

[@BrucesShop]

Right on. I thank you Tom. I learned more about the vacume test for crank seals.

[@VintageEngineRepairs]

Thanks for stopping by Bruce!

[@sonofthunder.]

i have a 034 super,and regular 034,and a donor 034 rebuilding to 036...48mm,gathering the seal ,bearing tool,case splitter,spark plug port test adapter, and carb test plate, i did get a cheap ebay vac ,pressure tester,thanks for the video,soon ill have the donor repaired

[@swordfish1120]

Good video. I just bought a Mityvac and spent the better part of an hour trying to seal a Stihl 193t. I kept getting leakage but I couldn't locate it. I finally found a small hole in my impulse line. I did have low compression which is why I wanted to do the pressure and vac tests. Can a hole in an impulse line cause lower compression? Can the Mityvac be used to test the rings?

[@ZingaraJoe]

Excellent presentation, I recently got a pressure vac unit like yours as shops in the area do not use them. Lots of trial and error and as a customer I don't like paying for the trial and error. Had a piston go in a Stihl and I knew it was not lacking oil in the gas, though maybe stale gas. Lugging with dull chain is another possibility but first rule out vacuum leaks.

[@garrydeimert7397]

Nice presentation my friend easy to follow for us old muckers 😅

[@VintageEngineRepairs]

Thank you! :)

[@sergiuadrianspulber2636]

great stuff. very useful info. thank you for that

[@VintageEngineRepairs]

You’re welcome

[@davidmech2956]

Brilliant information. Thank you.

[@ericwhitfield8475]

Great video, best wishes.

[@VintageEngineRepairs]

Thanks!

[@RYANINBODEN1547]

Question. I have a DT100 and I've done a bottom end swap (cracked case was reason) The old bottom end with top end still ran okay but when I put in new gaskets and did a swap i put my hand over the carb and i feel ZERO suction and no gas getting on my hand. It is 100% not a top end or carb issue at this point I don't believe and it has amazing compression and consistent blue spark. Had to swap points plate and flywheel for it but other then that it's all original. Just wondering if this would be a crank seal issue or what the matter could be.

[@VintageEngineRepairs]

Yep, without a pressure and vacuum test you’ll wasting your time. 👍

[@barney1941]

i just received the mighty vac mv8500 kit. now i have to figure out how to use it! thank you fine sir, a masterful tutorial! bravo! i collected 3 stihl 026 saws over the years that need work. i'm too old for dirt bikes, finely tuned chainsaws are the new hobby. thanks for the well explained tutorials. what brand of seals and bearings are quality? (if you are a chainsaw guy) i'm new to chainsaw parts procurement.

[@VintageEngineRepairs]

Great to hear! The mityvac is fantastic. If you want the best, go oem. If you don’t mind using aftermarket visit a bearing and seal dealer. Don’t buy from eBay or Chinese retailers. Their quality control is poor and you’ll likely end up with a leak.

[@treecycle4631]

Is the spray bottle you use for the soapy water a special purchase or just a generic bottle from some previous life?

[@VintageEngineRepairs]

It use to have foaming soap that I got from the BBQ Section of Bunnings for testing gas leaks :) edit: I actually brought it because it was a small compact bottle. Now it just has dish soap in it!

[@dinhomaquinaseferramentas4047]

How did you make this adaptation in this sparkplug

[@VintageEngineRepairs]

Yep!

[@mreasy4581]

Good explanation thanks sir 🫡

[@VintageEngineRepairs]

You’re very welcome :)

[@breikowski]

I was able to use the hose from my compression test kit. Had to remove the valve to open the line.

[@breikowski]

Did not look forward to hollowing out a spark plug then rigging in a barb fitting making it sealed tight. Glad I was able to avoid it.

[@VintageEngineRepairs]

Awesome! Good work

[@willdubeast88]

Air leaks can cause an engine not to run at all, right? Everything I read online says that the engines just won’t run right. I got a red max ebz 8500 that won’t run. It’s got fuel spark and compression, but is failing pretty bad and pressure and vacuum. So thinking it may be that

[@VintageEngineRepairs]

It can cause it not to run, yes.

[@EndreSzabo-Azabaj_hogy]

Hi could you post a link where to buy this tool? Thanks

[@VintageEngineRepairs]

Hey, I don’t have one, just google mityvac 8500 👍👍

[@everythingnerd7168]

I am having a hard time finding the source of the leak. I have tried soapy water and oil. I can hear the air coming out but i cant tell where it is coming from. Any more tips on identifying the cause of the leak?

[@VintageEngineRepairs]

Yes :) stick it in a bucket of water! That’s always my last resort 👍🏻

[@everythingnerd7168]

@ I sprayed it one more time with soapy water. It turns out I hadn’t been thorough enough. I had checked the decompression valve but I hadn’t gotten any of the soap down to the threads were the leak is. It still leaks with a new valve. Do you think loc tite would fix it or am I only going to damage the threads more trying?

[@justinf1343]

My daughter had a 2006 3 cylinder VW Polo (terrible engine) valves were always burning out and a leak down test showed me which cylinder was the problem.

[@VintageEngineRepairs]

Yep :) leak down, on a 4 stroke is very handy!

[@chenangokid]

should it hold for how long ?

[@VintageEngineRepairs]

About 30 seconds I test for.

[@chenangokid]

thanks for the reply. i recently tested a chainsaw. and it held a few minutes. but i left it on and came back later and it bleeded down great videos.

[@VintageEngineRepairs]

@@chenangokid pleasure, sorry for the delay, it’s easy to miss comments! Tiny leaks like you have that hold but will eventually bleed will not cause an issue, other than if you’re a perfectionist and want to find it lol. Ideally it’ll hold indefinitely, but most all manuals specify a short holding period something around 30-60 seconds.

[@joebrighton1075]

Can you please tell me what the adapter is called that you screw into the spark plug hole. Can’t find one anywhere, and everyone I ask doesn’t know what I’m talking about. Kind regards

[@VintageEngineRepairs]

Sure Joe, I made one from a spark plug! Cut the metal crimp off around the porcelain and it will seperate from the metal. From there remove the crush washer, add an o-ring and Jb weld / epoxy in a barb and it’s done!

[@joebrighton1075]

Thank you very much for replying, off to the shed to find an old plug 👍.

[@bostonmountain]

Thank you so much for sharing your deep knowledge. I'm linking your video to my FB page, and encouraging my friends to Like and Sunscribe. #StayAwesome!

[@VintageEngineRepairs]

That’s awesome thanks!!

[@yvonblanchette3682]

My engine is stripped like yours, is it normal that without plugging the two portes and rotating the shaft I get vacuum at the plug.?

[@VintageEngineRepairs]

Without plugging what two ports?

[@yvonblanchette3682]

@@VintageEngineRepairs the carburetor and the exhaust

[@menditman2004]

Great video, I’m into small engine but have never done this you video has explained it well. Have you got a link for the tool? I’ve just subbed your channel. I do have a channel myself if you have a moment please take a look. Thanks 🙂👍

[@menditman2004]

@@VintageEngineRepairs Hi I think I’ve found it, I’ll get one ordered it’s will be a very handy tool for me to have, thanks again for the video🙂👍

[@robbidi123]

No need to build a custom tool. A compression air hose nozzle will screw right into the sparkplug hole. Both are 14mm with same pitch.

[@VintageEngineRepairs]

That’s great when you have the right size adapter / the kit, but the ease of this for when you don’t is handy for people to make at home very affordably.

[@t008mx]

how dd you remove the internals from the spark plug , have tried a hacksaw but getting nowhere fast

[@TheLawnmowerLady]

I chiseled away with an hammer and punch to clear out a plug to make a piston stop. It was a bear.

[@jerrysoutherland662]

I use a old compression gauge hose,,cut the hose to length,and use one of the accessories that comes with the mityvac.I also use a golf tee to plug the impulse line.

[@VintageEngineRepairs]

kzbin.info/www/bejne/jabOgGyXmdtjmdU

[@t008mx]

@@VintageEngineRepairs Thankyou so much for making this video much appreciated .

[@murrayhowe8388]

Fastest Screwdriver in the North......

[@VintageEngineRepairs]

Haha

[@Catatonicwater]

Where are you buying that tool for $50???

[@VintageEngineRepairs]

Not this one, you can but a generic version from EBay. Or at least you could back then! Prices have gone up of course

[@torkrench]

Inches of mercury In/hg

[@VintageEngineRepairs]

Yes sir!

[@fanussmit5810]

I would like to have that mityvac. Dont get one in South Africa

[@THEMOWERMEDIC1]

Amazon maybe?

[@VintageEngineRepairs]

Yep spot on, Amazon :)