STIHL 034 Seal Problem

[J Arnold]

I was gifted a Stihl 034 after a local shop gave the owner "too high an estimate for repairs". The shop told the owner that the piston was scored and that he had probably run the saw on straight gas. I looked in the exhaust port and the piston was scored but not as bad as some I have seen from straight gassing. I ran a pressure test on the saw and found that it would not hold pressure. I then did the soapy water routine and found the culprit seal on the flywheel side. It was blowing bubbles. But now comes the issue, the bubbles were without a doubt coming out between the metal body of the seal and the boss in the housing that it was pressed into. I figured a previous seal repair had gouged the seal boss in the housing. After carefully pulling the seal with a seal puller, I found the problem. There is a very slight, looked machined, groove in the boss. The grove had to have been done during manufacturing. It is extremely shallow and perfectly straight, but it allowed air in through it. The seal itself has a corresponding buildup of residue in a perfectly straight line from the years of leaking. See attached photos. It was next to impossible to get a good photo of the groove in the boss of the case, but the grove can be detected in the second photo directly opposite the tapped hole on the right side. After doing some measurements I think I can press the new seal in deep enough in to get it to seal, almost to the bottom of the boss. The question is how far in is safe? My measurements will keep the seal from contacting the bearing. Has anyone else had such a problem and does anyone have any recommendations on how to repair it other than replacing the case? Thanks to all for your help.

 

[lone wolf]

I was gifted a Stihl 034 after a local shop gave the owner "too high an estimate for repairs". The shop told the owner that the piston was scored and that he had probably run the saw on straight gas. I looked in the exhaust port and the piston was scored but not as bad as some I have seen from straight gassing. I ran a pressure test on the saw and found that it would not hold pressure. I then did the soapy water routine and found the culprit seal on the flywheel side. It was blowing bubbles. But now comes the issue, the bubbles were without a doubt coming out between the metal body of the seal and the boss in the housing that it was pressed into. I figured a previous seal repair had gouged the seal boss in the housing. After carefully pulling the seal with a seal puller, I found the problem. There is a very slight, looked machined, groove in the boss. The grove had to have been done during manufacturing. It is extremely shallow and perfectly straight, but it allowed air in through it. The seal itself has a corresponding buildup of residue in a perfectly straight line from the years of leaking. See attached photos. It was next to impossible to get a good photo of the groove in the boss of the case, but the grove can be detected in the second photo directly opposite the tapped hole on the right side. After doing some measurements I think I can press the new seal in deep enough in to get it to seal, almost to the bottom of the boss. The question is how far in is safe? My measurements will keep the seal from contacting the bearing. Has anyone else had such a problem and does anyone have any recommendations on how to repair it other than replacing the case? Thanks to all for your help.

Put some sealant on the seal when installing. As far as installation depth goes, was it flush when you pulled it out, most are that's where I would install it. The sealant will work if you allow it to dry. When retesting pressure if it leaks in the same spot you can put more sealant on the outer rim until it stops.

 

[J Arnold]

Put some sealant on the seal when installing. As far as installation depth goes, was it flush when you pulled it out, most are that's where I would install it. The sealant will work if you allow it to dry. When retesting pressure if it leaks in the same spot you can put more sealant on the outer rim until it stops.

The seal was flush when I removed it. I had considered some kind of sealant but was hesitant to try it. What type of sealant do you recommend? Thank you for your quick reply and suggestions.

 

[ihookem]

Most use silicone . There is gasket sealer. However , once you get that saw going strong , you will really like the 034. I bought mine new in March of 1992 . It went back after 7 yrs, of my main saw for an ignition module that was fixed under lifetime warranty. Last year I took it in for a whopping $132 repair. A carb rebuild and something else. It's not my main saw anymore , only cause I like to have several saws, but if I only had 1 saw , it would likely be my 034.I still use the saw a lot.

 

[Oletrapper]

The seal was flush when I removed it. I had considered some kind of sealant but was hesitant to try it. What type of sealant do you recommend? Thank you for your quick reply and suggestions.

Dirko-HT is what I use. Great stuff and tuff. OT

 

[lone wolf]

The seal was flush when I removed it. I had considered some kind of sealant but was hesitant to try it. What type of sealant do you recommend? Thank you for your quick reply and suggestions.

Automotive Silicone will work Yamabond,Hondabond etc! You can use Locktite also, which actually seems to creep into tighter spots better. If you have a new seal that was just installed and a leak on the outer rim where the case was scratched taking the seal out, and you put vac on the engine you can draw some Locktite in to stop the leak . Let it get pulled in take vac off after a few minutes let dry repeat as necessary. Sometimes if the new seal leaks at the inside lip where it rides on the crank you can spin the motor over with the plug out with a 3/8 impact driver at the flywheel nut and set the seal better so it dont leak this works a fair amount of times with new seals there could be dirt or something there.

 

[Mad Professor]

Automotive Silicone will work Yamabond,Hondabond etc! You can use Locktite also, which actually seems to creep into tighter spots better. If you have a new seal that was just installed and a leak on the outer rim where the case was scratched taking the seal out, and you put vac on the engine you can draw some Locktite in to stop the leak . Let it get pulled in take vac off after a few minutes let dry repeat as necessary. Sometimes if the new seal leaks at the inside lip where it rides on the crank you can spin the motor over with the plug out with a 3/8 impact driver at the flywheel nut and set the seal better so it dont leak this works a fair amount of times with new seals there could be dirt or something there.

A good trick to know.

Sometimes it's poor installation and the spring gets disturbed in the seal

 

[lone wolf]

A good trick to know.

Sometimes it's poor installation and the spring gets disturbed in the seal

Grease packed into the spring can lessen the chance of it moving.

 

[Mad Professor]

Grease packed into the spring can lessen the chance of it moving.

Thanks!

 

[av8or3]

Automotive Silicone will work Yamabond,Hondabond etc! You can use Locktite also, which actually seems to creep into tighter spots better. If you have a new seal that was just installed and a leak on the outer rim where the case was scratched taking the seal out, and you put vac on the engine you can draw some Locktite in to stop the leak . Let it get pulled in take vac off after a few minutes let dry repeat as necessary. Sometimes if the new seal leaks at the inside lip where it rides on the crank you can spin the motor over with the plug out with a 3/8 impact driver at the flywheel nut and set the seal better so it dont leak this works a fair amount of times with new seals there could be dirt or something there.

That’s good stuff there. I’m really glad you put that out there. I use grape jelly (anaerobic flange sealant) I think it’s Locktite 1505, on mine and I have used High Strength Locktite thread sealant on ones that were “loose” fitting. I’ve had cases that were scratched pretty bad but none leaked afterwards.

 

[av8or3]

It’s not been mentioned yet so I’ll toss it out there. Everyone’s seal pullers will work better if you push the seal in a little bit to break its bond to the case, before attempting to pull it out. Just tap one side in a little.
Works lots better!

 

[teacherman]

Automotive Silicone will work Yamabond,Hondabond etc! You can use Locktite also, which actually seems to creep into tighter spots better. If you have a new seal that was just installed and a leak on the outer rim where the case was scratched taking the seal out, and you put vac on the engine you can draw some Locktite in to stop the leak . Let it get pulled in take vac off after a few minutes let dry repeat as necessary. Sometimes if the new seal leaks at the inside lip where it rides on the crank you can spin the motor over with the plug out with a 3/8 impact driver at the flywheel nut and set the seal better so it dont leak this works a fair amount of times with new seals there could be dirt or something there.

That’s good stuff there. I’m really glad you put that out there. I use grape jelly (anaerobic flange sealant) I think it’s Locktite 1505, on mine and I have used High Strength Locktite thread sealant on ones that were “loose” fitting. I’ve had cases that were scratched pretty bad but none leaked afterwards.

It’s not been mentioned yet so I’ll toss it out there. Everyone’s seal pullers will work better if you push the seal in a little bit to break its bond to the case, before attempting to pull it out. Just tap one side in a little.
Works lots better!

Thank you for all of the tips. The 034 is my second favorite saw, right behind the 044. Then comes the 064, and then the 024. I have cherry specimens of all four models, two each of the 034 and 044. I would like to get good at seal replacement. I have the Stihl seal puller, though I notice Chinesium versions are now out there...

I'd like to know how to find Stens seals for each model, without having to trust my own measurements once I pull them out. Or that company in Chicago that makes many of the OEM seals, I can't recall the name.

 

[teacherman]

Do you tap the new one in with a right-sized socket? SHould the seal be put in the freezer for a bit to shrink the metal housing?

 

[lone wolf]

Thank you for all of the tips. The 034 is my second favorite saw, right behind the 044. Then comes the 064, and then the 024. I have cherry specimens of all four models, two each of the 034 and 044. I would like to get good at seal replacement. I have the Stihl seal puller, though I notice Chinesium versions are now out there...

I'd like to know how to find Stens seals for each model, without having to trust my own measurements once I pull them out. Or that company in Chicago that makes many of the OEM seals, I can't recall the name.

Why not OEM seals? The IPL for the saw should list the seal measurements.

 

[lone wolf]

Do you tap the new one in with a right-sized socket? SHould the seal be put in the freezer for a bit to shrink the metal housing?

I use the Stihl seal driver its better than a socket, that part will be in the repair manual. @ray benson

 

[Mad Professor]

Thank you for all of the tips. The 034 is my second favorite saw, right behind the 044. Then comes the 064, and then the 024. I have cherry specimens of all four models, two each of the 034 and 044. I would like to get good at seal replacement. I have the Stihl seal puller, though I notice Chinesium versions are now out there...

I'd like to know how to find Stens seals for each model, without having to trust my own measurements once I pull them out. Or that company in Chicago that makes many of the OEM seals, I can't recall the name.

Stihl OEM gasket sets cost less than the seals alone

Why not OEM seals? The IPL for the saw should list the seal measurements.

 

[teacherman]

Why not OEM seals? The IPL for the saw should list the seal measurements.

I guess primarily because the older models have been obsoleted or are at least harder to find. Someone on here was talking about this at length, that there was a seal and bearing company that supplies many companies' OEM parts for them. If I can find the name of it. I'll share it.

 

[teacherman]

It's called Chicago Rubber & Seal. A picture from their web page:



https://sourcerubber.com/

 

[stihltech]

Seals still available for an 034. Just did one.