crank bearings and seal leaks when new

[thompson1600]

I just put new main crank bearings in an 026. On the sprocket side, the new seal leaked around the outside edges (not in by the crank). I tried to reseat the seal and it still leaked.

Before wasting lots of money on trying a different oil seal, I was wondering if it could be the bearing, bearing placement, or most likely just a defective oil seal.

They are Stihl bearings and seals.

Any help would be appreciated before wasting more money.

Thanks

Tom

 

[Grande Dog]

I tried to send the whole service manual but it's 2.5 MB and this AS system only will take up to 2.0. I scanned this page so hopefully it works. I looked at the section 13.2 it refers to for the sealant but, it doesn't show it. I would think Permatex #2 or silicone would work.

Grande Dog
Master Mechanic
Discount Arborist Equipment and Tree Care Supplies

 

[ozflea]

Did you apply a little sealant to the outer edge of the seal before fitting, use a non harding sealant in this application.

Bob Cornwell.......ozflea........Australia

 

[thompson1600]

What is the best generic (hardware store/auto parts store) type sealant to use? Any name brands that have worked? Thanks

Tom

 

[stihltech]

seals

Sealant may help, but putting in the seal ABSOLUTLEY SQUARE is the answer. I haven't had to put sealer on a Stihl seal in years. They make those solid gold installation tools for a reason.

 

[Ranchero50]

From a professional mechanics perspective (industrial, not automotive) the square drivers are pretty dang important for a good install as is not dinging the seal or flipping the seal ring. For a sealer, we use permatex ultra RTV ($5 at Autozone) and it works very well even in some fuel enviroments.

My only question is are you sure it's leaking around the seal to case mating point? As a test I'd fill the case and jug up with mix gas and see where it leaks out from. I did this on my 041 that had a vacuum leak and found a crack in the case where a carb nut had gotten down in the case and the crank whacked it.

Jamie

 

[thompson1600]

I checked it with soapy water and the leak is coming from the mating surface of the outside of the oil seal (metal to metal connection) and the bearing.

Stihltech, I did actually use the Stihl "gold" seal install tool, but it just didn't seem like the seal was completely seated down in, but I'm not an expert on that. Then tried again using the tool, and then with a deep socket, all with the same results, bubbles when using the pressure test. If there are any tips or advice on using these presses or putting these things in please let me know.

Thanks

Tom

 

[sedanman]

Are you using a pressure tester with a guage? The pressure and vacuum numbers a seal sees in actual use may be lower than you are testing at, your seals might not leak in actual use. Most Stihl saws specify 7psi for pressure and 15 inches of mercury for vacuum.

 

[thompson1600]

yes a pressure tester with a gauge going to about 4 bars. It releases pressure down to 0 quite quickly.

Tom

 

[sedanman]

Had to ask.

 

[thompson1600]

No problem, I'm trying to learn to do this stuff right.

Tom

 

[DanMan1]

Most Stihl saws specify 7psi for pressure and 15 inches of mercury for vacuum.

Wouldn't life be easier if everyone used one system for measurement, such as pressure, instead of PSI, inches of mercury, and bars all to describe the same thing? Now I have to get my conversion chart.

 

[stihltech]

seal

The drivers are pretty simple, just go square. But once you have driven a seaql and cocked it, it is pretty much shot. Iwould get another seal and use the sealer as the bore may be scratched.

 

[glens]

yes a pressure tester with a gauge going to about 4 bars. It releases pressure down to 0 quite quickly.

Tom

You are aware that 4 bar is almost <b>60 PSI</b>, right?&nbsp; Using Paul's figure of 7 PSI and your gauge, you'll be shooting for 0.48 bar.

Glen

 

[thompson1600]

sorry forgot a decimal point .4 bars, should be about 6 or so PSI

Tom

 

[glens]

whew!

 

[Lakeside53]

I think Stihltech is onto your likely problem, and maybe the mating surface of the bearing might have been scratched or gouged by someone levering out the old seal with a screwdriver?


I've put a lot of Stihl seals in, never used sealant, pressured tested all of them, and never had a problem except for when I drove one in too deep (by using the wrong tool!).

Check one more thing though - are you sure it's leaking around the seal, or is it actually leaking around the bearing to crankcase interface? (sometimes it's hard to tell as it's less than 1mm away. I've seen bearings on the clutch side that have become loose due to vibration from a flywheel missing fins,a and these leak like crazy. If that's happened, you'll need a another set of crank casings... and the bearing will be worn on the outside, so chuck it.

 

[Lakeside53]

I tried to send the whole service manual but it's 2.5 MB and this AS system only will take up to 2.0. I scanned this page so hopefully it works. I looked at the section 13.2 it refers to for the sealant but, it doesn't show it. I would think Permatex #2 or silicone would work.

Hmmm... yes the manual does show sealant. Somehow Ive never seen that mentioned in the manual before, but it's definately there!

Digging around I found that the recommneded sealer is Stihl part number 0783 830 2120. It's actually a Dirko product.

Maybe I've been lucky, but I haven't used sealant (on 026/36/44 types) and had no problems. I have used a Permatex product called HPF on 025, 020T BR400s and in many other places where gaskets are marginal and it's hard to get a pressure/vac test to hold. This would make great sense on the flywheel side as the seal pushes directily into the magnesium casing, and these scratch/scrape very easily.

 

[Lakeside53]

Wouldn't life be easier if everyone used one system for measurement, such as pressure, instead of PSI, inches of mercury, and bars all to describe the same thing? Now I have to get my conversion chart.

"everybody" does, except for the United states!

 

[WRW]

"everybody" does, except for the United states!

Ya got my curiosity up. Which one does everybody use?