Perplexed

[samaritan]

My Stihl ms251c when started races then stalls, wtf?

 

[Lawless]

Air leak?

 

[samaritan]

B

Air leak?

Bingo! I found that a cover of some sort fell off the right side of the engine, how strange, no bolts or screws holding it on, no cement or silicone, I'm waiting for a call back from a Stihl dealer, it must not be under pressure, or it would be attached better, probably like a valve cover I'm thinking. I'm gonna put it back on with high temp silicone and see what happens, at first the guy said, "you probably have to buy a new cylinder"- what a dumb thing to say, I'm a mechanic, I fix things, not replace unless no other option.

 

[Wood Doctor]

Transfer cover, similar to another thread in progress here? I have to wonder why Stihl engineered this design and what they used to hold that part in place. The Service Manual doesn't offer a clue.

 

[samaritan]

A

Transfer cover, similar to another thread in progress here? I have to wonder why Stihl engineered this design and what they used to hold that part in place. The Service Manual doesn't offer a clue.

according to tech support at Stihl, its a special cement, and once the cover comes off you cant fix it, well I'm gonna try anyway, if not, I buy a new cylinder, right?

 

[SteveSr]

A

according to tech support at Stihl, its a special cement, and once the cover comes off you cant fix it, well I'm gonna try anyway, if not, I buy a new cylinder, right?

Not a good idea. The piston may or may not be reusable. If you run it any more it won't be. You may also ruin the bearings in the crank and bottom end with debris from the next spontaneous disassembly.

 

[samaritan]

Not a good idea. The piston may or may not be reusable. If you run it any more it won't be. You may also ruin the bearings in the crank and bottom end with debris from the next spontaneous disassembly.

I plan to re-attach it using ultra high heat cement, if it doesnt work, I scrap it all and buy a new cylinder, the bearings are sealed arent they?

 

[samaritan]

I suspect it came off due to overheating caused by a blocked exhaust screen-just a theory, I believe in cause and effect.

 

[J D]

You may find the overheating was the result of running lean due to the cover leaking before it came off. I'd be pulling the muffler & inspecting the piston before going any further

 

[samaritan]

yeah, now that I understand these engines better, I believe it was running lean. I did inspect the piston, it looks steller. Thanks for the good info.