Stihl repair help please

[VW Splitter]

A friend sent this saw home with me and ask if I could check it out. It was making a bad rattling sound when you tried to crank it and it would not start. Looks like the side of the cylinder was just flopping loose. What is this and what is supposed to hold it together?

 

[4CornersPuddle]

The loose part appears to me to be a transfer port cover. Since there are no screws holding it on, Stihl must have used some fancy adhesive which has failed.
I'm not familiar with this type of set-up, but one of our repair experts will chime in soon.

 

[The Shooters Apprentice]

Looks like the transfer cover. What model is the saw?

 

[VW Splitter]

I don’t know the model number. The little sticker on the crank cover is missing. I’m guessing it’s about a 55cc saw. It is wearing a 20” bar. I will need to ask my friend that sent it with me what model it is.

 

[Kel71]

Man that sux. I hope it did not damage the piston or cylinder.

 

[SteveSr]

A friend sent this saw home with me and ask if I could check it out. It was making a bad rattling sound when you tried to crank it and it would not start. Looks like the side of the cylinder was just flopping loose. What is this and what is supposed to hold it together?

That is known as a glued on transfer cover. Saw was abused and overheated enough to melt the glue and ruin the engine.

Pull the muffler and post a pic of the piston through the exhaust port.

BTW, what make and model saw is it?

 

[Woodslasher]

Stihl MS391 as I recall. @HarleyT

 

[Bob Hedgecutter]

Stihl MS391 as I recall. @HarleyT

271-291 311-391 had glued on covers I think- not sure, I like to avoid them like the plague.

 

[HarleyT]

1141 is the prefix for ms271/291.

 

[VW Splitter]

It is a MS271. I did a compression check before I dug into it. It made 150psi. I will post some piston and cylinder pictures later today. I'm sure it takes a special glue to put it back together?
Thanks

 

[VW Splitter]

Sorry about the terrible pictures. Hard to get a good picture in the exhaust hole. Pictures through the transfer cover were a little bit better. there is a little bit of scoring both on the piston and cylinder walls. But it does have 150 psi compression. The saw was pretty dirty. Could it have been dirty enough to retain a lot of heat and causing glue to come loose?

 

[SteveSr]

Sorry about the terrible pictures. Hard to get a good picture in the exhaust hole. Pictures through the transfer cover were a little bit better. there is a little bit of scoring both on the piston and cylinder walls. But it does have 150 psi compression. The saw was pretty dirty. Could it have been dirty enough to retain a lot of heat and causing glue to come loose?

Compression numbers are irrelevant. The condition of the piston tells the tale. That is now a parts saw.

As for cause the saw was overheated which loosened the glue enough to cause a lean condition which burned up the motor. The cause of the overheating could be old gas or cutting with a dull chain, etc.

 

[VW Splitter]

Compression numbers are irrelevant. The condition of the piston tells the tale. That is now a parts saw.

???? Will it not run with decent compression, 150psi ? Is gluing the transfer cover back on and running it not an option?
Please explain.

 

[SteveSr]

???? Will it not run with decent compression, 150psi ?

No, the piston and cylinder are all scored up. If it did happen to start it wouldn't run for long. You might as well pull it apart the rest of the way and take a look. Consider it an education in failure analysis caused by a piss-poor design.

Is gluing the transfer cover back on and running it not an option?
Please explain.

No, Where would you get the proprietary Stihl engineered high temperature adhesive and the industrial process to properly cure it?

The saw is trash. Time to move on...

 

[huskihl]

Piston looks fine from here. I’d clean out all the old adhesive and JB weld them back on. Good to go for another 100k

 

[Tobystihl]

Looks good to me

 

[a. palmer jr.]

???? Will it not run with decent compression, 150psi ? Is gluing the transfer cover back on and running it not an option?
Please explain.

That's what I'd do if it was mine. JBWeld, the good kind would hold that on I'd imagine. Just glue it on and give it a try!

 

[cscltd]

Depending on age, Stihl may cover that under warranty or possibly a parts only, but dealer would have to install. Might be worth a try as some have had this issue.

 

[stihltech]

Will another adhesive work under the heat cycle conditions? Doubtful but who knows?
The piston shows light scoring up and down. Could be a partial lean seize. I would be more concerned with a bearing cage coming apart on the crank. Needs a tear down.
Serial number please.

 

[VW Splitter]

Will another adhesive work under the heat cycle conditions? Doubtful but who knows?
The piston shows light scoring up and down. Could be a partial lean seize. I would be more concerned with a bearing cage coming apart on the crank. Needs a tear down.
Serial number please.

Serial Number info.