steveotm357
ArboristSite Lurker
from what i can see the boot looks fine...the impulse line is just a generic rubber hose that seems real hard instead of being flexible...can the seals leak so much there is no pressure at all???
Need to rebuild 038 magnum
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hard impulse can leak @ either end or be cracked
put pressure to it [5-10psi] and put soap/water mix on seals
i never have, but some will pressure it then put in bucket of water
put pressure to it [5-10psi] and put soap/water mix on seals
i never have, but some will pressure it then put in bucket of water
steveotm357
ArboristSite Lurker
it looks solid but hard rubber is usually a problem...guess i will just get it off and try to hook the pump directly to the crankcase...looks like maybe 5/16...till i get my order for parts...tried the soapy water but get absolutely no pressure on the gage at all
A major leak is hard to find with soapy water because you can't pressure the cranckcase.
If you can't see a big crack in the impulse or carb boot. Your leak is probably somewhere else.
To rule out the rubber on the carb side you can remove the carb and clog the boot with a screw driver handle, you thumb or something like that.
If you can't see a big crack in the impulse or carb boot. Your leak is probably somewhere else.
To rule out the rubber on the carb side you can remove the carb and clog the boot with a screw driver handle, you thumb or something like that.
steveotm357
ArboristSite Lurker
i have removed the carb and put rubber gasket material behind it...but i am now thinking its either not thickor flexible enough...going to revisit that too...thanks so much for the info!!!
I take a picture of what i use to vaccum/pressure test a Stihl chainsaw :
On the left it's an homemade metal plate to plug the boot. I remove the carb and mount the plate with two sockets and the carb nuts.
On the right it's the rubber gasket for the exhaust side.
On the left it's an homemade metal plate to plug the boot. I remove the carb and mount the plate with two sockets and the carb nuts.
On the right it's the rubber gasket for the exhaust side.
steveotm357
ArboristSite Lurker
what is the best way to remove the seals??? saw a way by drilling a hole and putting a screw in it...is there a better way???
steveotm357
ArboristSite Lurker
i am going to recheck those...i am starting to think that if i am going to replace the seals and have to get to the piston anyway...should i just remove the cylander and see what parts are bad??? prob should just replace all the rubber parts anyway while i am in there???
I'd recommend a piece of rubber inner tube between the metal plate and the boot.
That's what I did, just be REALLY careful. I believe Stihl makes a special seal puller tool.
PTO side is easy to remove with 2 screw. For the flywheel side i use a modified screwdriver. Look at this thread: https://www.arboristsite.com/threads/what-tool-works-best-for-crank-seal-removal.247507/
steveotm357
ArboristSite Lurker
i think i will try that first...so should i just continue disassembly instead of the pressure/vac test since i have to get to the piston anyway? then i can change all the rubber and test on reassembly??? this way i can get my parts order in and clean it all up while waiting??? Can i order oem from somewhere online or have to go local?
Tear it down and replace both seals, fuel hose, filter, pulse hose, any other wear items that look questionable really. Vac/pressure test after reassembly. If you have a local Stihl dealer just go in and tell them what parts you need. They may have some in stock but will most likely have to order them in for you. I am unaware of any online source for genuine Stihl parts.
steveotm357
ArboristSite Lurker
before i pull the seals i want to get all the grease and grime out of there...is carb cleaner ok???whats better???
Carb cleaner is fine, just make absolutely sure you have no dirt or grit in the bearings when your done. You may want to pull the seals out before cleaning. That way you can get the bearings at the same time.
Scrape off the thick stuff then a stiff parts brush and an old toothbrush. Diesel will loosen up the grime then hit with detergent
steveotm357
ArboristSite Lurker
when i hit with detergent is water an issue if the seals are still in???
I try to clean it as I take it apart. Parts that come off can go in a bucket (recoil bar/clutch covers clutch oil pump...) Water should not get past the seals unless they are shot. Clean around the muffler before you pull it off. Once you have the clutch/flywheel off you can scrape the gunk out then hit things with the diesel/brushes. Diesel won't hurt a thing. Try to avoid getting any grime/dirt into the intake/exhaust. An oiled piece of rag should plug those up.
Here is a 038 I did and it's clean enough to pull the jug. Still be careful then as you never get every bit of grime around base of jug (see picture).
Have some rags or towels handy to stuff in around the crank.
This one I had to split cases as ate some bearing material.
Here is a 026 I got for $90. Ran/Runs great but it was one of the filthiest saws I'd seen. That is after a good bath
steveotm357
ArboristSite Lurker
Great pics! another question...this saw was always a hard start...should i consider changing the ignition or wouldnt that have anything to do with it???
