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

[slowcar281]

I’m working on an old 025 that has sat for years. It was stored dry, and had one of those non adjustable H carbs. Rather than try to rebuild it, I installed a new genuine walboro wt215 carb.

the carb will not hold a tune at all. It starts and idles ok. I tried adjusting the rpms to 12.5. Sometimes it will hold them, other times it will shoot up to 15k. Sometimes it will go full lean in the middle of a cut and instantly shut off! But it always restarts. Sometimes it runs perfectly fine. The piston and cylinder are in great shape. No scoring

the saw is old and I figured it might have an air leak.. I tore the whole saw down and installed new crank seals, impulse line, fuel line and fuel filter. Resealed the pan with dirko sealant. I double and triple checked the intake boot and found no tears. Let the saw sit overnight and fired it up and…. It runs EXACTLY the same.

I would really like to try and fix it, but I have no idea what direction to go now.

 

[IthacaMan]

I think first question will be , pressure and vacuum test was done?

 

[slowcar281]

Unfortunately I don’t own any of the equipment to do that. Don’t you need special adaptors for the intake and a block off plate for the exhaust ?

 

[IthacaMan]

Unfortunately I don’t own any of the equipment to do that.

You can use the search to read up on how to make your own test equipment for cheap. You really just need to make a block off between muffler and cylinder with a piece of rubber . And block inlet to carb. Not sure on the 025 , but maybe make a temporary impulse line with a tee in it for the testing. I have an 025 , I will take a look at it tomorrow to see what the easiest way would be

 

[slowcar281]

I’ll take a look and see what I can find. I’m very surprised that it would run exactly the same after doing all this work.I’ve replaced seals on several clamshell engines before and they always ran fine afterwards. The carb is so finicky, on the high side the smallest of turns can account for 2000 rpms. That doesn’t seem normal at all.

 

[HarleyT]

What is the part number of the seals you put in?

 

[slowcar281]

What is the part number of the seals you put in?

9639 003 1585 I bought the seals that you use when the case pan is removed. The springs on the seals faced inward

 

[HarleyT]

Did you put in an aftermarket fuel line?

 

[slowcar281]

Did you put in an aftermarket fuel line?

No sir, the only thing that was aftermarket was the impulse line. The dealer wasn’t able to get one anytime soon, so I got one from Amazon. It fit tightly on both ends so I doubt that’s an issue. I examined it very closely before installing it.
Also as far as the seals go,( I wanted to make sure I got the right ones ) the dealer showed me an ipl and it only shows one set of seals. But the spring did faced inward towards the bearings

 

[HarleyT]

Did you run the new carb a while before deciding to replace the fuel line?

 

[IthacaMan]

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.

 

[IthacaMan]

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.

 

[Okie294life]

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. If you don’t any to spend a bunch of money on a vac tester a dealer can pressure the saw for you usually cheap, if you’re a regular. When you installed the seals did you get them on straight? Have you checked the torque on head bolts? Sometimes these get stripped or the bolts may be contaminated with grease or something causing them to back out. Could be a leak on the intake boot also. Good luck and kudos on having the wherewithal not to run a saw leaned out.

 

[slowcar281]

Did you run the new carb a while before deciding to replace the fuel line?

yeah I ran a few tanks through it before deciding that it probably had an air leak. I constantly had to fiddle with the carb cause I could hear the Engine was running too fast. I then replaced everything else.

 

[slowcar281]

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. If you don’t any to spend a bunch of money on a vac tester a dealer can pressure the saw for you usually cheap, if you’re a regular. When you installed the seals did you get them on straight? Have you checked the torque on head bolts? Sometimes these get stripped or the bolts may be contaminated with grease or something causing them to back out. 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’m not really a regular anywhere. I screw around with saws more for fun than anything. Im 99% sure I installed everything correctly. I’ll try turning it side to side again and try spraying the seal/ engine pan area with carb cleaner to see if the engine rpms change. It’s weird cause at times the saw runs perfectly fine and will hold the rpms just fine. Other times it runs away and shuts down as if you hit the kill switch

 

[SteveSr]

I’m not really a regular anywhere. I screw around with saws more for fun than anything. Im 99% sure I installed everything correctly. I’ll try turning it side to side again and try spraying the seal/ engine pan area with carb cleaner to see if the engine rpms change. It’s weird cause at times the saw runs perfectly fine and will hold the rpms just fine. Other times it runs away and shuts down as if you hit the kill switch

This seems to say that you have an intermittent major air leak somewhere. A pressure tester and a bucket of water should show you wear.

Since you live near the coast and salt air you may have corrosion in the cylinder pan. I had one of these that ran surprisingly good (due to a stiff as a board metering diaphragm). Before I tore it down I did a pressure test only to find that the engine pan had corroded through due to being stored a little too close to the ocean.

 

[AHart81]

bayou country saw has a video on an 028 stihl mentioned he didn’t like Walbro because hard to tune and putting a gasket between intake boot and carb fixing same issue. That doesn’t discount the pressure/vac test. Just an idea if you don’t have any leaks.

 

[slowcar281]

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.

 

[Vintage Engine Repairs]

If you want to repair 2 strokes, make your first investment a pressure and vacuum tester.

You are literally throwing money away if you’re putting new parts on without testing it.

For the money you’ve wasted throwing new OEM parts and still not found the issue,you could have owned a pressure and vac tester already and found your issue.

 

[slowcar281]

I agree 100%