oil seal leaking at outer edges

[thompson1600]

I put a new oil seal on the flywheel side of an 084. Pressure test shows very small leak. Checked with soapy water and found that flywheel side oil seal is leaking around the outer edges.

What can be done, short of buying a new crankcase or having this one machined and an insert put in? Is there a "duct tape" type fix that will work? (ie gasket sealer, etc)

Thanks

Tom

 

[havvey]

oil seal

i am not a guru on stihl but on other saws we put sealer, rtv or indian head and put in the seal as what your describing is common. now unless you got a worn housing and if so a new case half might be needed. hope this helps don't laugh this has worked for us since the 60's :yoyo:

 

[RaisedByWolves]

Green loctite will seal up that bugger just fine. It is actually a bearing retaining compound for use on unperfect bearing fits.

DO NOT get it Inside the bearing or it will become a bushing.

 

[Lakeside53]

The stihl manual on the 088 calls for Dirko.... 084 isn't any different around that seal. I used it and had no leaks on my 088..

Don't sweat a small leak around the outer edge. It won't affect anything and I bet it's gone after an hour of use. Remember, the "spec" isn't perfect vac or pressure - usually measured to .2 bar after 20 seconds. Having said that, I do like to see perfect pressure and vac, but that's just me.

 

[havvey]

The stihl manual on the 088 calls for Dirko.... 084 isn't any different around that seal. I used it and had no leaks on my 088..

Don't sweat a small leak around the outer edge. It won't affect anything and I bet it's gone after an hour of use. Remember, the "spec" isn't perfect vac or pressure - usually measured to .2 bar after 20 seconds. Having said that, I do like to see perfect pressure and vac, but that's just me.

me too on the pressure/vac!! :yoyo:

 

[Lakeside53]

o.k., instead of relying on my failing memory... I looked up the manual for the pressure and vac test.

Pressure: "using a test pressure of 8.7psi (0.6bar) if the pressure stays constant for 20 seconds, then the seals are in good order". Obviously they mean "detectable change..." 'cos if it's not leaking the 20 seconds means nothing!

vacuum: :"if the reading remains constant or rises to no more then 0.3 bar (4.25psi) in 20 seconds, the seals can be considered to be in good order".

And yes, Stihl wants you to use the Dirko product on the outer edges of the seals.

 

[Simonizer]

Green loctite will seal up that bugger just fine. It is actually a bearing retaining compound for use on unperfect bearing fits.

DO NOT get it Inside the bearing or it will become a bushing.

More specifically, Loctite 290.

 

[thompson1600]

And yes, Stihl want you to use the Dirko product on the out edges of the seals.

Do you put the Dirko sealant on prior to installation of the seal, or spread it on after the seal is installed?

Thanks

Tom

 

[Simonizer]

Do you put the Dirko sealant on prior to installation of the seal, or spread it on after the seal is installed?

Thanks

Tom

Since the seal is already installed, take a toothpick and administer a tiny amount of Loctite 290 around the perimeter. It will "wick" into the area and seal it. Don't pull the starter or do anything with the saw for 12 hours. Your problem will be solved.

 

[Lakeside53]

Do you put the Dirko sealant on prior to installation of the seal, or spread it on after the seal is installed?

Thanks

Tom

Prior to installation. Spreading it afterwards will do nothing to halt any leak. How bad a leak is it? How long does it take to get to .3 bar?

 

[RES]

I think what Simonizer says it worth a try. I looked up my Loctite catalog. Threadlocker 290 is formulated especially to lock pre-assembled fasteners. It penetrates by capillary action. It is also used to seal welds.

 

[RaisedByWolves]

More specifically, Loctite 290.

Nope, 680 is the bearing retaining compound.


Were not allowed to use the wicking grade at work, they consider it a hack job.

It actually needs a little space to migrate properly and may not peneterate deep enough into the fine gap that could cause a substantial leak.

 

[Lakeside53]

It actually needs a little space to migrate properly and may not peneterate deep enough into the fine gap that could cause a substantial leak.

I agree, and it may not adhere particularly if you use oil for assembly and soapy water to detect...


Either ignore a small leak (tiny leaks in the outer portion tend to seal with crud quickly) or rip out the seal and use Dirko.

Also, as it's on the flywheel side, you have a little more depth to play with to seat the seal. Try tapping it in slightly deeper..

 

[RES]

I would think that if an adhesive would wick up into a threaded fastener, it would have no problem with the bearing seat. You could also draw a little vacuum with your pressure tester while applying the Loctite.

 

[RES]

Loctite Data Sheet
http://65.213.72.112/tds5/docs/290-EN.PDF

 

[Lakeside53]

I would think that if an adhesive would wick up into a threaded fastener, it would have no problem with the bearing seat. You could also draw a little vacuum with your pressure tester while applying the Loctite.

be careful.. it's a seal seat (not bearing), and if you draw with a vacuum, you could suck it right into the bearing. The seal is is only a $5-$10 part.. I'd either leave it alone or replace it.

 

[RaisedByWolves]

I make threaded holes all day sometimes.


Most common threaded holes are a 75% thread ingagement and when pulled tight there is a 25%(or so) gap on the backside of the thread, this is where the wicking action takes place and where the product cures.


With that bearing leak there is probably 97-98% contact therefore not a whole lot of room for a significant amount of penetration.


Not saying its a bad idea, just better to pull it and sael it if it needs fixing.

 

[thompson1600]

It is a very slow leak. I pumped it up to .5 bar and it leaked down maybe .1 bar in 20-30 seconds. It held ok on vacuum test. I'm just a perfectionist with these test, I figure if I have it torn down this far I want it perfect before going on. However, for the price of seals, I also don't want to waste money.

I ordered two tubes of Dirko, should be here tomorrow. Do you just put a small amount on the outer edges of each seal you put in?

So, what's the consensus, have to replace the seal, or put the sealant on the installed seal? Hate to have a lean seize a few months from now, from a seal failure.

Thanks

Tom

 

[Lakeside53]

It is a very slow leak. I pumped it up to .5 bar and it leaked down maybe .1 bar in 20-30 seconds. It held ok on vacuum test. I'm just a perfectionist with these test, I figure if I have it torn down this far I want it perfect before going on. However, for the price of seals, I also don't want to waste money.

I ordered two tubes of Dirko, should be here tomorrow. Do you just put a small amount on the outer edges of each seal you put in?

So, what's the consensus, have to replace the seal, or put the sealant on the installed seal? Hate to have a lean seize a few months from now, from a seal failure.

Thanks

Tom

You''d need a :"poll" to get a consensus"

I wouldn't put sealer (or loctite) on an installed seal. Either replace it and do it right, or leave it alone. Locitite is going to cause a problem for the next guy installing a seal, and guy that might be you.

And yes, a tiny smear of dirko on the outer lips of the seal. I put a tiny amount around the casing also. Be sure to grease the inner dust seal cavity.

You not going to get a "lean seizure" from this. Lean seizure is NOT caused by tiny leaks in crank seals. They only affect idle, and even then only when the leak is quite pronounced. Leaks in boots etc are a different story.

The seal hasn't failed - failure that would be the inner portion where it contacts the crank. You're just having a surface mating problem on the non-moving portion. Additionally, it's well within Stihl factory new spec (which is why they publish a spec, not just say "hold pressure forever"), and that you have no leak on vac suggests most strongly that the "problem" is tiny.

Get it running, and if you test in a tank or two, I bet the tiny leak has gone.