Old stihl 025 running issues. Not sure what to do now !

[cookies]

Had one do the same wonky shlt recently, carb had sawdust between the diaphragm and its cover reducing its ability to flex. once the saw warmed up and needed more fuel it started giving me fits. Drove me nuts figuring it out. There was sawdust in the pump side cover too.

 

[slowcar281]

Had one do the same wonky shlt recently, carb had sawdust between the diaphragm and its cover reducing its ability to flex. once the saw warmed up and needed more fuel it started giving me fits. Drove me nuts figuring it out. There was sawdust in the pump side cover too.

thanks for the suggestion, I’ll pull the carb and inspect it as well. Can’t hurt at this point.

 

[Fuzy6525]

028 driving me crazy. Just broke down and bought a Miteck pressure/vacuum tester from Home Depot. Around $55 and got it in 2 days. Helped me track problem to impulse line. Best money spent. If you haven’t rebuilt the carb start there

 

[Woodslasher]

Yeah one way or another I’ll have to either invest in the correct tools to pressure test it or take it somewhere. For what a dealer will probably charge, I might be able to buy the tools myself.
I don’t have much faith in dealers around here. Years ago before I was familiar with stihl clamshells I called a BUNCH of dealers asking what they would charge to put seals in a 039….. they all refused, wouldn’t touch it, too old….. too much money…..not worth it and told me to just buy a new saw I still have that saw today and it runs great after replacing the seals myself.
I’ll do some research on a vac tester. If someone knows which tester is best and exactly what adaptors I need, I would greatly appreciate it.

Here's what I bought, you'll need a few small pieces of tygon too but any local small engine shop should have some.
https://www.ebay.com/itm/223614542401

 

[slowcar281]

Here's what I bought, you'll need a few small pieces of tygon too but any local small engine shop should have some.
https://www.ebay.com/itm/223614542401

thats the exact kit I was Looking at. I’m assuming you block off the exhaust and carb and pressurize it through the impulse line ?

 

[Woodslasher]

thats the exact kit I was Looking at. I’m assuming you block off the exhaust and carb and pressurize it through the impulse line ?

I actually have a husky tool that screws into the plug hole and has a nipple to hook the mityvac to, but yes using the impulse is how I'd recommend that others do it.

 

[TRTermite]

Just trying to help does it rev up or die when you lay it over on one side? A lot of time that is indicative of a seal leak on one side or another. Could be a leak on the intake boot also. Good luck and kudos on having the wherewithal not to run a saw leaned out.

I don't see many compliments for having the foresight to NOT use a saw running lean.... I liked that part of your post the most..

 

[Fuzy6525]

Here's what I bought, you'll need a few small pieces of tygon too but any local small engine shop should have some.
https://www.ebay.com/itm/

 

[Fuzy6525]

Sorry, it was the Mityvac not the other brand I said in earlier post. Just make sure its a vac/pressure gauge not just a vacuum gauge. Most of the fittings you can find at a hardware store or buy that whole kit of course.

 

[slowcar281]

I don't see many compliments for having the foresight to NOT use a saw running lean.... I liked that part of your post the most..

Haha, yeah I guess I have a trained ear for knowing when it’s lean. We had a storm come through and lots of little trees fell from the heavy snow. I went around cutting stuff up for the neighbors.
I put it down after adjusting the carb for the 100th time. I have a 046, ms362 and a 039 to cut with.

 

[RogerD]

I did not go look at my 025 yet, but just remembered . try spraying small amounts of cleaner spray in different spots to see if RPM changes to find leaks. Here is a clip I found. And afleetcommand on utube has a trouble shooting vid somewhere on trouble shooting leaks.

be sure you are using flammable brake cleaner, some is not these days

 

[RogerD]

Yeah one way or another I’ll have to either invest in the correct tools to pressure test it or take it somewhere. For what a dealer will probably charge, I might be able to buy the tools myself.
I don’t have much faith in dealers around here. Years ago before I was familiar with stihl clamshells I called a BUNCH of dealers asking what they would charge to put seals in a 039….. they all refused, wouldn’t touch it, too old….. too much money…..not worth it and told me to just buy a new saw I still have that saw today and it runs great after replacing the seals myself.
I’ll do some research on a vac tester. If someone knows which tester is best and exactly what adaptors I need, I would greatly appreciate it.

dealers these days can be such hacks. they dont understand easy economics. how much will they profit on a new saw sale vs how much will they profit with labor/parts charges? likely more with the latter.

 

[RogerD]

I also have 025 that is giving me fits with running condition. I have been through the carb and it will run fine one minute and wonky the next. Does this model have a history of ignition issues? I am going to get it warmed up and try running with a spark checker to see if that is the issue one of these days when I can scrounge up the time.

 

[SteveSr]

I also have 025 that is giving me fits with running condition. I have been through the carb and it will run fine one minute and wonky the next. Does this model have a history of ignition issues? I am going to get it warmed up and try running with a spark checker to see if that is the issue one of these days when I can scrounge up the time.

Can you quantify "wonky"?

Its likely carb and/or intermittent air leak. Unlikely ignition.

 

[RogerD]

Surges, lean. You know, wonky lol. Bought it at a pawn shop and it was pretty rough when I got it. I need to bring the carb to work so that I can throw it in the sonic cleaner. I may be able to borrow some block off plates to pressure test engine.

 

[SteveSr]

Surges, lean. You know, wonky lol. Bought it at a pawn shop and it was pretty rough when I got it. I need to bring the carb to work so that I can throw it in the sonic cleaner. I may be able to borrow some block off plates to pressure test engine.

These also tend to leak around the cylinder pan joint. Could be anything at the 25-30 year old age of this saw. I would check/replace carb diaphragms with OEM and/or possibly install a WT-215 if it came with a Zama (will need a new carb screw grommet for this).

 

[slowcar281]

Small update. I sprayed the saw all over focusing on the seal areas and the engine pan. No rpm changes. I then sprayed the top and bottom covers on the carb and it almost instantly lowers the rpms and kills the saw. I checked all the screws and they are tight.

 

[SteveSr]

Small update. I sprayed the saw all over focusing on the seal areas and the engine pan. No rpm changes. I then sprayed the top and bottom covers on the carb and it almost instantly lowers the rpms and kills the saw. I checked all the screws and they are tight.

This is likely not telling. You have slight leaks near the throttle and choke shafts and it also might be getting sucked in though the air filter/intake.

What happens if you clamp the bar in a vice and bend/stress the A/V system? This may show the leak.

 

[slowcar281]

This is likely not telling. You have slight leaks near the throttle and choke shafts and it also might be getting sucked in though the air filter/intake.

What happens if you clamp the bar in a vice and bend/stress the A/V system? This may show the leak.

I was very careful not to spray it in the air filter but I guess it’s possible I got some in there.

I had pulled the bar and bar cover and was spraying it down with just the power head running. It started acting up almost immediately, running erratically.
I’ll put the carb back on and reassemble the bar and try stressing the av system.
I went ahead and ordered a mity vac 8500 kit

 

[SteveSr]

I tore the whole saw down and installed new crank seals, impulse line, fuel line and fuel filter.

Were these OEM or AM parts? AM hasn't figured out anything rubber yet...