Replace bearings Stihl MS310?

[Pim]

Started on a new project a MS310 of 2002. I got it running but after heating up it revved up on its own and died. So suspected an air leak.

Started disassembling the saw, during the process I found the root cause. One bolt of the cylinder was loose. The complete thread was gone in cylinder.

An easy fix with bolt and nut. Put in a new gasket and oil seals. But I noticed that the bearings have some play on them. But I don’t know if this is normal or too much play.

I made a video:

Should I replace the bearings or just leave them?

 

[trains]

If it was mine, I would replace the bearings whilst its all apart like that, thats quite some movement there.

T

 

[Conquistador3]

A bit too much play. Quite a bit too much I'd say.

The MS310 uses the same crankshaft bearings as the rest of the 1127 family (029, MS390 etc) so they are pretty common. Originals were made by either FAG or SKF but you should have no problem with any reputable brand: just avoid suspiciously cheap bearings and seals from the Far East and you should be fine.

Edit: did I write "026" instead of "029"? Long term concussion damage is really as bad as they say.

 

[holeycow]

you might want to check that rod too...

 

[HarleyT]

We don't say "FAG" here in the states anymore...

 

[HarleyT]

SKF is an outright hate crime!!

 

[a. palmer jr.]

If it was mine I would consider this a great time to change it over to a 390. New bearings, seals, and the 390 P/C kit, muffler mod, carb adjust and you have a much healthier saw!

 

[Pim]

Thanks for the feedback, I will also replace the bearings.

you might want to check that rod too...

I checked the rod (after watching some YouTube vids on what to look for).
There is some sideway play, but no up/down play at all on the rod bearing. So the rod is fine I think.

If it was mine I would consider this a great time to change it over to a 390. New bearings, seals, and the 390 P/C kit, muffler mod, carb adjust and you have a much healthier saw!

Cylinder and piston are in very good shape, so will keep the OEM Stihl in.
Enough power for me!
Recently I had some bad experience with aftermarket cylinder (see other thread).

 

[Conquistador3]

We don't say "FAG" here in the states anymore...

FAG

In Germany: a brand of bearings
In England: a cigarette
In the US: a word that sends some people into a "Hulk Smash!" fury, especially on social media

Now I am confused.

 

[HarleyT]

All of America has been confused for @ a decade.

 

[holeycow]

In Canada: a Prime Minister

Currently

 

[Pim]

I received the bearings and oil seals and rebuild the saw.
Did a test run today, it cuts fine with lots of power.
But can't get it to idle properly.

Before discovering the air leak I replaced the fuel line, impulse line, carb kit and fuel filter and put in fresh fuel (Stihl moto mix)
It’s a different problem then before. With the air leak I couldn’t get it start anymore when it was heated up.

I tried to adjust the carb when the saw was heated up. I started with L and H 1 turn out. But the saw died quickly when idle. So turning LA in, then it keeps running idle but too fast with chain spinning. Adjusted the L screw for the sweet spot. But when turning LA out again so the chain doesn't spin anymore it died again. Didn't turn the H screw yet.

Does somebody have some tips?

 

[HarleyT]

Start with both screws @ 1 1/2 out, then dial it in.

 

[blsnelling]

Is there any radial play in those main bearings? If not, they're fine.

What's this gasket you replaced?

 

[traffic903]

Is there any radial play in those main bearings? If not, they're fine.

What's this gasket you replaced?

Good catch! Did he mean sealant?

 

[Pim]

Start with both screws @ 1 1/2 out, then dial it in.

Thanks, that did the job. It runs and idles super!

Good catch! Did he mean sealant?

Yep, with gasket I meant sealent

 

[SoopermanLuva]

I agree with what Brad said. Even new bearings will have some axial play in them. It's just a characteristic of deep groove ball bearings, they are not really designed to take these loads. That's why there's one on each side, which reduces axial load. I have a new bearing laying around that also has play in it. It all goes away when both bearings are fixed in place. You can try to put the crankshaft into the case, tighten the bolts some and see if the shaft has play in those bearings. My guess is it doesn't.

Not meant as an insult. I do enjoy the name of that company.

 

[Pim]

I allready replaced the bearings with new ones (SKF) to be on the safe side, they are not that expensive.
The new bearings have also some play, but less then the old ones.

 

[dmb2613]

We don't say "FAG" here in the states anymore...

and you cant call side cutters dykes

 

[HarleyT]

and you cant call side cutters dykes

Only the ones wearing flannel shirts on the softball team.