Stihl Crank Seal installation Questions

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FernGreen

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Hey guys, so I did my first crank seal install on my 034 today on the flywheel side and the new seal is leaking. I used a 3/8" drive 14mm deep socket to install it but I had a hard time keeping the seal from going crooked as I installed it. I got it pretty level but it failed vacuum and after a couple repeated tests it started to fail under pressure as well. I used simple green to see the leak on the seal. Is there a better way to drive a seal in besides using a socket? Is there some special tool to get it to the right depth? I tried to measure the old seal depth the best I could with a caliper and set the new one in at approximately the same depth. Also should I apply a thin layer of yamabond on the outside edge of the next seal I install?
 
Hey guys, so I did my first crank seal install on my 034 today on the flywheel side and the new seal is leaking. I used a 3/8" drive 14mm deep socket to install it but I had a hard time keeping the seal from going crooked as I installed it. I got it pretty level but it failed vacuum and after a couple repeated tests it started to fail under pressure as well. I used simple green to see the leak on the seal. Is there a better way to drive a seal in besides using a socket? Is there some special tool to get it to the right depth? I tried to measure the old seal depth the best I could with a caliper and set the new one in at approximately the same depth. Also should I apply a thin layer of yamabond on the outside edge of the next seal I install?
Stihl makes the proper installation driver Google it or Ebay it ,make sure it says for the flywheel side. I use Locktite on my sealed it penetrates better. Did you remove the flywheel key and put a piece of old style film or something over the groove,I bet not. The key can cut the seal .
 
Stihl makes the proper installation driver Google it or Ebay it ,make sure it says for the flywheel side. I use Locktite on my sealed it penetrates better. Did you remove the flywheel key and put a piece of old style film or something over the groove,I bet not. The key can cut the seal .
Check your pm box i sent you a repair manual.
 
Stihl makes the proper installation driver Google it or Ebay it ,make sure it says for the flywheel side. I use Locktite on my sealed it penetrates better. Did you remove the flywheel key and put a piece of old style film or something over the groove,I bet not. The key can cut the seal .
I didn't use the film trick, i thought that only applied to huskys? but I did remove the flywheel key prior and the seal wasn't small enough to touch the keyway so i don't think that was the issue.
Is it leaking between the seal and crank or seal and housing - or both?
It looks to be leaking between the outside part of the seal and the housing.
 
I didn't use the film trick, i thought that only applied to huskys? but I did remove the flywheel key prior and the seal wasn't small enough to touch the keyway so i don't think that was the issue.

It looks to be leaking between the outside part of the seal and the housing.
Put a small amount of sealer or locktite by the leak on it and check tomorrow at this same time. Maybe even suck in some with the vac part of the gauge.
 
Put a small amount of sealer or locktite by the leak on it and check tomorrow at this same time. Maybe even suck in some with the vac part of the gauge.
Great idea! I'll pick up some yamabond 4 tomorrow. What kind of locktite do you use? Like thread locker or one of their sealants?
 
If you put a gob of greese over the leak it will seal then you can test to see if the center leaks also at that time if it does you tore the seal.. Did you scratch the cases when you pulled the seal out that will cause lots of trouble?
I'll try the grease trick first before I pull the seal. But before i installed the new seal i made sure the surfaces were undamaged since i was worried beforehand about using my newly made notched screw driver.
 
when installing a new seal, put grease on the rubber part of the seal, both sides. Be carful not to get the grease on the metal part of the seal. Spray some copper coat in a cup, enough to puddle good. Then paint the out side of the seal with a little model car paint brush. After it gets good and tacky install the seal. You can use a beer can to wrap the crank.
 
when installing a new seal, put grease on the rubber part of the seal, both sides. Be carful not to get the grease on the metal part of the seal. Spray some copper coat in a cup, enough to puddle good. Then paint the out side of the seal with a little model car paint brush. After it gets good and tacky install the seal. You can use a beer can to wrap the crank.
Will do thanks!
 
As stated above and for future readers, the 1125 flywheel side crankshaft has clearance to accept a seal. I do pull the key before installing seals, yes. The gradual taper allows for a quick drive with the oem driver.

To the OP- if that sealant doesn’t work (it wont if the sealing ring came off the seal or it’s inverted), a trick we use is to stack washers on top of the seal and drive it flush to the case first, then carefully tap it home with a socket. Starting with a socket can cause it to go in crooked as you saw.

The film or coke can trick is great for any model saw that has a step in the crank (pto) near the seal surface. This includes 1125 Stihls, 1122 Stihls, and 046/460. 044/440 have the 372-style bushing so it isn’t needed.
 
As stated above and for future readers, the 1125 flywheel side crankshaft has clearance to accept a seal. I do pull the key before installing seals, yes. The gradual taper allows for a quick drive with the oem driver.

To the OP- if that sealant doesn’t work (it wont if the sealing ring came off the seal or it’s inverted), a trick we use is to stack washers on top of the seal and drive it flush to the case first, then carefully tap it home with a socket. Starting with a socket can cause it to go in crooked as you saw.

The film or coke can trick is great for any model saw that has a step in the crank (pto) near the seal surface. This includes 1125 Stihls, 1122 Stihls, and 046/460. 044/440 have the 372-style bushing so it isn’t needed.

Thank you for all the info I’ve definitely learned some new tricks
 
Are you using Chinese seals? You mention it’s between the outer surface and crank case. Possible damage or pitting there will cause you these issues. It’s the reason stihl recommends sealant on the outside of the seals. Also if they are metal seals and weren’t installed vertically you may have deformed / damaged the outer edge of the seal.
 

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