Stihl Clam Shells - Loose Bearing Pockets?

[SteveSr]

Hello,

Clam shells rely on a small gap to keep the bearing outer races tight and prevent them from rotating in their pockets.

I have recently come across a Stihl clam shell that appears to have been manufactured with loose bearing pockets. It is not a saw but a very low hour HS56 hedge trimmer with a small strato 2-stroke engine. The best that I can tell is that this is a manufacturing defect and was walking wounded on the day it left Virginia Beach..

Have any of you run into similar issues with any other Stihl clam shells?

Thanks,
Steve

 

[MartDalb]

Having worked on several HS56 trimmers, I have not had any issues with bearings, at all.

I do however, have seen several HS56 engines with oil seals popping out, on the flywheel side, rarely the clutch side.

No idea if that is related to what you describe here.

 

[SteveSr]

Having worked on several HS56 trimmers, I have not had any issues with bearings, at all.

I do however, have seen several HS56 engines with oil seals popping out, on the flywheel side, rarely the clutch side.

No idea if that is related to what you describe here.

Well, this is the FW side with the loose bearing pocket(s). The engine ran until the seal wallowed out creating an air leak.

 

[MartDalb]

Well, this is the FW side with the loose bearing pocket(s). The engine ran until the seal wallowed out creating an air leak.

Yep sounds like the ones I have seen.
At least two or three times within the last year alone.

Easy fix but...poor design?

 

[SteveSr]

Yep sounds like the ones I have seen.
At least two or three times within the last year alone.

Next one that you get check for lateral crankshaft movement on the FW side. You may have more than just a seal issue.

Easy fix but...poor design?

I wouldn't call complete disassembly and parts replacement to the engine internals an easy fix. I don't know if this is a design or manufacturing issue.

 

[angelo c]

Next one that you get check for lateral crankshaft movement on the FW side. You may have more than just a seal issue.


I wouldn't call complete disassembly and parts replacement to the engine internals an easy fix. I don't know if this is a design or manufacturing issue.

It's an easy job....finding all the time to do the repair is the hardest part. Clams are unnecessarily time consuming witches...

 

[MartDalb]

Next one that you get check for lateral crankshaft movement on the FW side. You may have more than just a seal issue.


I wouldn't call complete disassembly and parts replacement to the engine internals an easy fix. I don't know if this is a design or manufacturing issue.

I have a complete engine somewhere I can find, it had the same issue, poped a seal on the FW side.
I can take a look at soon.

 

[MartDalb]

It's an easy job....finding all the time to do the repair is the hardest part. Clams are unnecessarily time consuming witches...

Yep, agree on all of that.

 

[SteveSr]

I have a complete engine somewhere I can find, it had the same issue, poped a seal on the FW side.
I can take a look at soon.

I am having a hard time figuring how the seals are popping out. Shouldn't bey be glued in with Dirko?

All the clam shells that I rehab get a light coat of Dirko all the way around the seals.

 

[MartDalb]

I am having a hard time figuring how the seals are popping out. Shouldn't bey be glued in with Dirko?

All the clam shells that I rehab get a light coat of Dirko all the way around the seals.

I do whatever the service manual tells me.
Never added liquid gasket to the oil seal area.

It is funny though. I have had so many thoughts about this same exact issue. Especially on the hs56c hedgetrimmer engine. It has to be a build error on stihls part, seeing this issue on so so many hs56s, and now you come along and bring it up as well.

Ill take a look at my spare engine tommorow.

 

[Vintage Engine Repairs]

All my seals get a coat of sealant typically Dirko or more recently I have moved to threebond 1215 which is the exact same as Yamabond 4. It doesn’t harden in the tube, it smells like mint and easy to wipe off your hands. There is a long work time too of 20-30 mins.

 

[MartDalb]

just curious, why add sealent, when the SM does not mention this at all?
I know some Husqvarna SMs do it, I recall, but never seen it on stihl machines or their service manuals.

 

[SteveSr]

Ill take a look at my spare engine tomorrow.

Did you ever get chance to look at this?

 

[MartDalb]

Did you ever get chance to look at this?

I will. Totally forgot, too much real life stuff lately.

 

[MartDalb]

Ok found it.

Got some pictures here.
The seal on the FW side, was poped out when I got this, I pressed it in at some point, but I would of course replace both seals when this engine needs to run again.

I dont' feel any crankshaft movement, with or without the pan on etc.
Anything else I could look for?

The only thing I really feel is that the seal is very easy to slide off.
Coming from replacing the seals on a Stihl MS171 just now this evening, they were more tight fight on.
I could be mistaken.

 

[SteveSr]

Got some pictures here.
The seal on the FW side, was poped out when I got this, I pressed it in at some point, but I would of course replace both seals when this engine needs to run again.

Interesting that it popped out even with some Dirko on it. On mine the Dirko stuck pretty good. I had to pry quite a bit to get the pan off.

I dont' feel any crankshaft movement, with or without the pan on etc.
Anything else I could look for?

The main issue that I am seeing with mine is bearing pocket slop and visible movement of the FW end of the crankshaft.

I am begining to wonder if there is too much Dirko on there causing a loose fit.

 

[MartDalb]

Interesting that it popped out even with some Dirko on it. On mine the Dirko stuck pretty good. I had to pry quite a bit to get the pan off.


The main issue that I am seeing with mine is bearing pocket slop and visible movement of the FW end of the crankshaft.

I am begining to wonder if there is too much Dirko on there causing a loose fit.

Could be a case of too much, I am not sure.
But something is up on these engines, this issue is so common.
I think I see a few each month for sale, "won't run/start issues", and it's more or less always the seal issue.

I just picked apart a Stihl ms171 that had very little, if not too little dirko, had an airleak from that.

 

[SteveSr]

I just picked apart a Stihl ms171 that had very little, if not too little dirko, had an airleak from that.

I have yet to run into a Stihl clam shell that didn't leak around the pan. However, most of these were over 10 years old.

 

[MartDalb]

Hmm I have had several which were fine, even 10+ years.

But, oddly enough I have had more issues with the "newer" models than the old ones.
Seens tons of fine working 029, 390, 025, 250, 180 etc. but most 171, 391, and similar have had issues with either leaks from pans or broken bearings etc.

Perhaps it's just me.