Why you do a pressure and vac test on a chainsaw, demo with 2 saws
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- Опубликовано: 2 фев 2016
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Disclaimer: ladies and gents, this is a CHAINSAW, working with, building and fiddling with these can KILL YOU, I am not and will not be responsible for improper technique or accidents even remotely relating to this video, please view for entertainment purposes only.
This video is intended to describe how and why to do a pressure test on a chainsaw. Please visit HL Supply for all your aftermarket chainsaw parts needs! 
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I have a small engine repair shop. A vacuum-pressure test is part of my standard assessment for two cycle equipment
Very helpful I have watched several videos on this and you were the only one to explain it how I could understand it, thank you.
Welcome!
Very informative to people that want to do a rebuild themselves. To make sure & pressure test and vacuum test. I think you & Dony are the best on here. I’ve been a tree contractor over 50 years. thank you.
welcome Ted!
excellent video. I'll be testing a 200t and this is just the info I was looking for.
ChaparralDenizen let me know if you have questions!
FYI, the most air leaks I have found are around the intake boot and it’s interface with the carb with an occasional leak on the base gasket due to loose bolts on the cylinder. Stihl says it must hold the pressure for two minutes and not drop below four pounds. When I built my ms 440 a small air leak drove me crazy until a Stihl technician told me the oil pump spacer will allow some leakage and was normal.
Which is why you use a husky pto bearing :) then there's no leakage :)
@@matthewolson8875 believe it or not. I never have had a leaking seal on the pto side of one of my Chinese saws. Have had to replace one or two on the flywheel side. I like the Farmertec seals on a Farmertec crank - they are tight on the crank. I have replaced a few parts more so out of an abundance of caution than anything else. One thing I really check is whether the fuel tank hold pressure or not. I have a 361 rear handle in the shop I have nicknames RMS Titanic because it leaks like a sieve. I pumped it to 7# and it started blowing bubbles all along the seams. I replaced it with another Farmertec rear handle and it never gave another problem and the second farmertec tank passed the pressure test. I replaced a lot of parts that I did not need to chasing down that problem. I finally caught it by letting it sit on the kitchen floor, where it dumped out gas on the floor. Then, I pressure tested it and replaced it.
Great up close detail and excellent instructions. Nice job!
thanks!
+LoveStihlQuality and please please please use my link to hlsupply if you are going to purchase parts, I'm running my chainsaw vids ad free hoping that enough support comes from people using that link.... happy diy-ing!
Enjoyed your video. Very helpful diagnosis procedures. Oil pump bolt holes , didn't know this .
Happy to help
10,000 TIMES thank you !.
you get 10 stars in my book you do i very good job of explaining things thank you
Welcome!
Thanks for the video they have been helpful for future work
Stephen Masterson your welcome!
Informative video. Nice work.
Thank you! Great video. I am getting ready to pressure test my Stihl 200T. Should I pressure test the saw only or should I look at the piston as well? Also do you have a recommendation for the pressure pump? I checked on hlsproparts, and I could not find any pressure pumps.
When I have a saw that runs but the carb doesn't seem to adjust right, or the rpm's change when it's idling, I do a pressure/vacuum test. A leaking crank seal can drive you crazy. If you work on small engines you have to have one of these pressure/vacuum testers. If you buy one make sure it tests pressure AND vacuum.
Nice comment...thanks
Great videos and very helpful. Thank you !!
Welcome!
Thanks man for making this video
Ah ik all to well about that let's say my brother inlaw brought my 395xp back bown up. Mhm almost 1,300 saw. It just passes me off. So needless to say he's never borrowing any of my saws again
Excellent info. and video . Thanks so much !!!!!!!!!!!!------------Ernest E. Johnson
Welcome!
Thanks
Thanks,, good video.
thanks :)
I have an old Poulan 25DA and it doesn't have an impulse line or a decompression valve. What is the best method for vacuum and/or pressure test this? Thanks for the video!!
block the intake and exhaust, and then add pressure via the spark plug hole with an adapter. you can either buy such adapters or make one.
So you mean that you're doing press./vac testing "in case of" a failure that was caused by over-lean, by way of air-intake at the seals? Overkill, no? Spraying some brake-kleen at such areas should let you know if anything's getting-in and causing over-lean (I would think- would love to know your thoughts!)
Not saying these tests are w/o merit, I'm actually still "deciding" if I'm going to further befriend the local mechanic or just buy such kits myself at this point (Oh yknow Re tools....Re case-presses for chinesium 660's...I know you acknowledge the 'simple' pressure-plates method is sufficient for this however I'm curious what you think of "fixing" a MIS-ALIGNED case by means of loosening all screws, giving it a good whack w/ the hard-rubber mallet, to correct a ~0.25mm or maybe 10thous misalignment that I have in a prebuilt Blue Thunder? Am guessing it's a big Nope but have to ask because it's either "try to ignore it, see how long it goes before FORCING you to rebuild the entire thing", or proactively get ahead of it....no way a misaligned crankcase is going to be a long-term viable machine...
I dont do a lot of pressure tests these days but it can be helpful. Most of the time its easier to just tear the saw down and do new seals than it is to set up a pressure test. The China cases can be ok....but I definitely prefer assembling them myself with my crank tools that way they are as good as possible. Preferably no whack with hammers hehe
Great Video.When pressure/vac testing whilst rotating crank how much movement is allowed with needle on gauge ?will the needle flick back and forth on some saws?
Yeah it'll go up and down but overall come back go the same place
Thanks Matt for the response and all the videos you do
What all do you have to take apart to replace the manifold boot on a Ms180c stihl chainsaw?
haven't worked on a 180, so I don't know, but I'd guess that you'd need to remove the head to change out the intake boot. it *MIGHT* be possible without removing the head, but it'd be much easier with the head off
Funny thing is rubber from the 50s 60s 70s, even 80s is often times fine without cracks at all, compared to the engineered to fail modern rubber rubbish.
Kevin Doble yeah...plenty of old saws still run lol....amazing.
Hey Matt I purchase one of your crank tools for the 044 Stihl chainsaw the inside threaded Rod broke on me can't believe it on the flywheel side can you let me know how much another one will cost me it's just for the flywheel side on the oh 44 and then ms440 it's the little one I don't know exactly what happened but it snapped everything else is working great like it should but I just need that one piece inner threaded rod for the flywheel side I would greatly appreciate it if get back with me on it thank you Matt
email sent!
I use a broken handle and put it on the manifold
where did you get the intake plug?
I think it was part of the mitivac kit ....was not a super effective plug. I usually end up using a 1/2" socket extension lol
just so you know on oem seals the lettering goes out
john Kosheluk good way to think of it...thanks
Movie Star Matt ... Good vids Matt.
MustangMikeBlueGT :)
MustangMikeBlueGT thanks Mike!
So,, one symptom of possible leaks is an engine the runs intermittently funky? Or an engine that won't tune, carb wise?
possibly... lots of reasons for intermittence... carbs can be intermittent too. you can use carb cleaner to spray in various places while a saw is running to see if the rpms change... if you spray say at the base gasket... and the saw suddenly stalls, you have a leak :)
Matthew Olson Thanks. Have done that with motorcycles, but with a two stroke so many more points of potential leaks. Does make sense with crankcase. being part of fuel air mix. thanks again.
is there a specific saw in question?
Matthew Olson Well I have a cs 300 Echo that I've rebuilt the carb, all fuel lines and vent line replaced ,,,started at first right after rebuild,, thought was fixed,, put it away for weekend then went to start, hard to start and continue to run, even warm would idle till die, hard to start. Thought OK crappy rebuild so bought new carb. Still hard to tune, always tune by ear, no meter or anything. Finally got it where it cranks seemingly normal and idles good but when i release trigger i have to rev to keep idle if I release quickly idle is unsure and sometimes dies but will restart. Sounds like carb settings tuneup but can't seem to get it perfect. Hopefully it's just adjustments.
how old is the saw?
Do you mean Mityvac or Minivac?
Mityvac 8500 is what I use
any tips on testing a saw without an impulse line?
gotta do it through the spark plug hole... its somewhere in my vids lol. 394 is a good example ... no impulse line except through the intake block, and you need to block that to test the rest of the block.
Matthew Olson ok, I will do some digging
Matthew Olson nup, couldn't find it
@@v26224 i'll make one with a 394 I'm working on ... hows that? ... i can't find it either
@@matthewolson8875 great, it was good excuse to do some binge watching anyway
Has to hold 3# for 3 minutes from 7#.
that is what stihl told me
john Kosheluk thanks....can you make a comment on my other seals vid?