Bad compression release? stihltech

[JimL]

I had an 046 come into the shop, bad piston& cyl, real bad.

I replaced piston and jug, then vac tested it, leak somewhere, replaced pulsar line, still leaked,

replaced both crank seals, still leaked,

pulled jug back off and replaced base gasket again, still leaked,

replaced intake boot, still leaked,

finally hit the compression release while under vacuum and it shifted my guage.

I pulled it out and cleaned it and it still leaked alot.

all the other parts(boot, hose, seals) so i guess this is what caused my leak? I put some valve lapping compound on it and it fixed it, but i replaced it anyway.
No leaks now.


Anyone else seen one of these things go bad?

 

[stihltech]

release

The proper way to test a compression release saw is to replace the release with a plug(yep, Stihl has em). When every thing else is OK, put the release back in and test it. I replace them if they leak, just no reason to take a chance.
I have to ask, don't you use a little soap and water to find the leak? Saves on replacing uneeded parts and labor. Just asking. I have even went so far as to dunk the saw in a bucket of water. Extreme, but I don't quit until it is perfect.

 

[crowe]

Jim did you take the compression release out and plug it off. Most replacement cylinders I get come with a plug or cap to fit where the compression release goes. I usually just plug them off on my smaller saws I never use the compression release anyway. I tell you though air leaks are a real pain in the but. Take care........Wade

 

[JimL]

the customer told me to replace the seals to begin with.
The pulsar hose was an item to be replaced anyway, i always do when i have the jug off.

Never thought about soap and water, but that wouldnt work on the vac test, thats when it leaked, not on the preasure test end of things.

Hehe never knew to plug them, now I do.

 

[crowe]

I have had a couple get a piece of carbon stuck in them. I try to clean my saws every sunday before the race I alaways try to blow the gunk out or take a brush to them. Since I have swithched to synthetic oil I hardly ever have to pull them out and clean them there is just no carbon build up to worry about......Wade

 

[stihltech]

testing

I admit I have the Stihl tools, but there is no rocket science there. Just need something to block off the intake and exhaust and a way to introduce pressure and vacuum into the case. The soap and water have served me well, even when using vacuum. Put a little around the seal and see if it sucks in. Never had any adverse efects, but the saw will clean out after the first run. Remember, I said a little.
Seal will usually leak on vacuum, gaskets show up under pressure (usually). But the compression release will go either way.

 

[Oregon_Rob]

Hmmm

FYI,
I had the opposite problem on the 372 I bought used. The logger never used it and it was froze closed. Took a lot of work to get it to free up. Works fine now. I didn’t consider that they might be replaceable.

 

[JimL]

if it were up to me it wouldnt be on the saw,
I got some plugs ordered for them,