Don't want a new saw. Stihl Problem

[Goat boy]

Hi everyone,
I have a 25 yr. old Stihl 025 I bought new. After researching here and elsewhere, I have what seems like a fairly common problem but have yet to find a good answer. It doesn't get used that often so after having carb problems I started using Trufuel and the difference in how it ran was amazing. After running perfectly it sat for about 6 mon, when I tried to start it recently I could barely pull the recoil cord and it would not start. I took the plug out and it turned normally. After research I started to diagnose things that were suggested. The plug was dry but I turned it upside down while pulling the cord and it wasn't flooded. Took the muffler off and it was amazingly clean inside, looked in the cylinder while turning it and the piston, 2 rings and cylinder wall look perfect. Took the bar, chain and sprocket off and the needle bearing, clutch and everything else looks fine. Doesn't seem to be a problem with the recoil. Read some posts about being out of time. Should I look at the flywheel and keyway next? Really hesitant to start tearing the whole thing down. I'm at at a loss so any suggestions are appreciated.

 

[Tomos770]

After 25yrs crank seals (although saw is barely used) are toast....rubber/plastic gets cracked/porous and saw evolves an air leak past those seals....

You dont need to tear whole saw appart to change those....

Just use tiny drill bit.....put 2 holes 180° appart (watch out that you dont go to deep with drill....and damage its bearings).....then you need 2 self treading (spax) screws.....and a pair of pliers to pull them out

Then some grease for new ones and a coresponding socket (in size) to push new seals in.....and a (Mc)hammer to tap them in

 

[samaritan]

Hi everyone,
I have a 25 yr. old Stihl 025 I bought new. After researching here and elsewhere, I have what seems like a fairly common problem but have yet to find a good answer. It doesn't get used that often so after having carb problems I started using Trufuel and the difference in how it ran was amazing. After running perfectly it sat for about 6 mon, when I tried to start it recently I could barely pull the recoil cord and it would not start. I took the plug out and it turned normally. After research I started to diagnose things that were suggested. The plug was dry but I turned it upside down while pulling the cord and it wasn't flooded. Took the muffler off and it was amazingly clean inside, looked in the cylinder while turning it and the piston, 2 rings and cylinder wall look perfect. Took the bar, chain and sprocket off and the needle bearing, clutch and everything else looks fine. Doesn't seem to be a problem with the recoil. Read some posts about being out of time. Should I look at the flywheel and keyway next? Really hesitant to start tearing the whole thing down. I'm at at a loss so any suggestions are appreciated.

 

[samaritan]

You could try shooting some oil into the spark plug hole too, this has worked on my lawn mower(s)

 

[Lawless]

See if a squirt of mix in the plug hole makes it feel better.

 

[SteveSr]

Hi everyone,
I have a 25 yr. old Stihl 025 I bought new. After researching here and elsewhere, I have what seems like a fairly common problem but have yet to find a good answer. It doesn't get used that often so after having carb problems I started using Trufuel and the difference in how it ran was amazing. After running perfectly it sat for about 6 mon, when I tried to start it recently I could barely pull the recoil cord and it would not start. I took the plug out and it turned normally. After research I started to diagnose things that were suggested. The plug was dry but I turned it upside down while pulling the cord and it wasn't flooded. Took the muffler off and it was amazingly clean inside, looked in the cylinder while turning it and the piston, 2 rings and cylinder wall look perfect. Took the bar, chain and sprocket off and the needle bearing, clutch and everything else looks fine. Doesn't seem to be a problem with the recoil. Read some posts about being out of time. Should I look at the flywheel and keyway next? Really hesitant to start tearing the whole thing down. I'm at at a loss so any suggestions are appreciated.

Seals and air leaks are a possibility but with these saws you have to pull it like you mean it!

Was the plug wet or dry after your last starting attempt?

 

[Goat boy]

After 25yrs crank seals (although saw is barely used) are toast....rubber/plastic gets cracked/porous and saw evolves an air leak past those seals....

You dont need to tear whole saw appart to change those....

Just use tiny drill bit.....put 2 holes 180° appart (watch out that you dont go to deep with drill....and damage its bearings).....then you need 2 self treading (spax) screws.....and a pair of pliers to pull them out

Then some grease for new ones and a coresponding socket (in size) to push new seals in.....and a (Mc)hammer to tap them in

I worked as a auto tech for almost 50 years but 2 cycle engines not so much. Please explain why hard seals would make it hard to turn. Is the air leak going into the cylinder because the crankcase and cylinder are connected?

 

[Goat boy]

You could try shooting some oil into the spark plug hole too, this has worked on my lawn mower(s)

Worth a try. I'll try this and report back.

 

[Goat boy]

Seals and air leaks are a possibility but with these saws you have to pull it like you mean it!

Was the plug wet or dry after your last starting attempt?

Yes the saw has been hard to pull since day one. Nature of the beast I have heard. I took the plug out not immediately but the same day after it wouldn't start and it was dry.

 

[coffeebrk]

Is this really happening....

 

[HarleyT]

A good possibility, if it seems to have too much compression, is that you have a good layer of carbon in the combustion chamber.

Leave the flywheel alone, to rule out the out of timing theory, simply leave the plug wire off and try to pull the rope.

 

[ZeroJunk]

Those saws are just hard to pull. Once the cylinder wall gets dry it is just that much worse.
It is a simple matter of displacement vs the gear ratio of the starter pulley which is the same as the MS170. Look at it like gears on a bicycle. Little pulley vs a larger displacement.

 

[Goat boy]

You could try shooting some oil into the spark plug hole too, this has worked on my lawn mower(s)

See if a squirt of mix in the plug hole makes it feel better.

First I tried mix then oil. Both made it worse, wouldn't turn at all.

 

[Goat boy]

Those saws are just hard to pull. Once the cylinder wall gets dry it is just that much worse.
It is a simple matter of displacement vs the gear ratio of the starter pulley which is the same as the MS170. Look at it like gears on a bicycle. Little pulley vs a larger displacement.

It will try to turn slightly and then it's just locked. Turns fine with plug out.

 

[buzz sawyer]

I worked as a auto tech for almost 50 years but 2 cycle engines not so much. Please explain why hard seals would make it hard to turn. Is the air leak going into the cylinder because the crankcase and cylinder are connected?

I had the same question. I've worked on an 025 and never saw a problem pulling the cord. Any chance this has a clogged screen in the muffler?

 

[Goat boy]

A good possibility, if it seems to have too much compression, is that you have a good layer of carbon in the combustion chamber.

Leave the flywheel alone, to rule out the out of timing theory, simply leave the plug wire off and try to pull the rope.

Doesn't want to turn with plug wire off. It was running fine when last shut off then it sat for about 6 months. Carbon build up is gradual, doesn't seem like this would be sudden. Did start using Trufuel the last few times I ran it, seems like that would help with carbon rather than hurt. Pull the cylinder head and look?

 

[Lawless]

It will try to turn slightly and then it's just locked. Turns fine with plug out.

Is the screen plugged in the muffler?

 

[Goat boy]

I had the same question. I've worked on an 025 and never saw a problem pulling the cord. Any chance this has a clogged screen in the muffler?

I can see the screen and it looks clear.

 

[Goat boy]

Is the screen plugged in the muffler?

No.

 

[Lawless]

So it pulls over perfectly fine with the plug out, but won’t with it in?

Exhaust has to be completely blocked or possibly the motor is locked with flooded fuel