Stihl ms 290/310

[rutterbe]

I am at the end of what I know to do with this chainsaw. I was given the chainsaw with a new piston to install. the old one was lightly scored. I cleaned up the cylinder and installed the new piston along with new bearings and seals I buttoned it up with permatex put it back together and it ran great. the saw was sold to a firewood guy. we tested in wood and it ran great. 2 weeks later it came back he said it would not idle when started. I tried it and it seemed to have an air leak. the piston that I put in was lightly scored so i took i apart and replaced the piston and jug with an after market ms 310 piston and jug. buttoned everything up and started the saw only to have the same symptoms as before. I rebuilt the carburetor still no good I replaced the pulse line and intake boot still same problem. I took it apart again and tried a different permatex sealent i even put it where the seals cradle in the block. have no more ideas. Any thoughts?

 

[irhunter]

Clamshell saws really really need a pressure/vac test after splitting the motor.

As you know, Permatex is a brand. What exact versions did you use?

You need a specifically-gas-resistant product. Motoseal or Dirko or......

Roy

 

[stihltech]

Stupid question, does the fuel hose have any cracks? #1 issues on these saws. Vacuum and pressure test a must, as stated before.

 

[Lightning Performance]

Stupid question, does the fuel hose have any cracks? #1 issues on these saws. Vacuum and pressure test a must, as stated before.

He mentioned the blue goo.
He didn't mention any test.

Maybe it is garbage AM rings taking a dump, like usual?
Possibly a seal missing a spring?
Cracked lines?
Missing intake retainer ring s?
Egg shapped bore from sanding?

Let's play 500 questions.
Yes?

 

[jltrent]

The impulse line is bad to crack on those fast.

 

[ZeroJunk]

I use Dirko. I know some have said Hondabond or Yamabond will work fine.

Permatex could be anything.

If you are still using the same carburetor that it cooked with originally it may have the same issue.

 

[stihltech]

Magic wand says

 

[ZeroJunk]

Well, it does the same thing with a new top end. You can look straight at the springs on the seals.
I have never had one leak around the sealant.
I'm not saying you can't screw that up.
He replaced the impulse line and the intake.
He didn't mention fuel line or filter I don't think..
So, it's lean from that direction.

What my magic wand says.

 

[Jasonrkba]

Replacing the fuel line and filter seems like a no brainer if you are replacing the cylinder and piston. How does the plug look?

 

[rutterbe]

Thankyou all for your input. Since my last post I replaced the fuel line also the tank vent.The gasket sealant I used was permatex motoseal 29132 fuel and oil resistant. I have since put in new seals and a new crank pan. I ordered a vac/pressure tester that should arrive tomorrow. I am letting the sealent cure for 24 hrs. I will try it again tomorrow after i pressure and vac test it. I know to block the intake and exhaust but which is the best way to test from. I would think it would be from the impulse nipple but I saw a video where the guy made an adapter for the sparkplug hole and tested from there. Please let me know.

Thanks

 

[Jasonrkba]

Did you replace the plug?

 

[rutterbe]

Yes The spark plug was replaced. the only thing that has not been replaced is the saw cradle that houses the motor.

 

[Jasonrkba]

I had a 290 one time that had a crack in the oil pan. I spotted it while replacing the top end. It would have been easy to miss. Im guessing the saw was dropped from a tree or truck.

 

[ZeroJunk]

Yes The spark plug was replaced. the only thing that has not been replaced is the saw cradle that houses the motor.

Please don't leave us hanging. I am quite curious about it.

 

[SteveSr]

Thankyou all for your input. Since my last post I replaced the fuel line also the tank vent.The gasket sealant I used was permatex motoseal 29132 fuel and oil resistant.

I am not sure that this is the correct Motoseal. I don't think that it is rated for gap-filling such as clam shells. You should be using a filled, high temperature RTV such as Dirko HT.

Leave it sit under pressure test for 15 minutes and see if it doesn't blow out a gap by the bearings.

 

[rutterbe]

FINALLY SUCCESS. I was just about to give up. I used the motoseal which was pretty soupy but it vac and pressure tested great. I put it back together again and now it was hard to pull over so i am thinking the motoseal got into the crankcase and was binding the crankshaft so I went and bought dirko sealant took the motor apart again and resealed it. The motor was still tight. i thought thats it i am done. Well it turned out to be the flywheel. I had the saw apart so many times that the flywheel had distorted to where it was rubbing against the crankcase. I changed the flywheel and now have a good running saw. NEVER AGAIN! Thanks for all of your inputs.

 

[Lightning Performance]

FINALLY SUCCESS. I was just about to give up. I used the motoseal which was pretty soupy but it vac and pressure tested great. I put it back together again and now it was hard to pull over so i am thinking the motoseal got into the crankcase and was binding the crankshaft so I went and bought dirko sealant took the motor apart again and resealed it. The motor was still tight. i thought thats it i am done. Well it turned out to be the flywheel. I had the saw apart so many times that the flywheel had distorted to where it was rubbing against the crankcase. I changed the flywheel and now have a good running saw. NEVER AGAIN! Thanks for all of your inputs.

Pics?