064 Muffler Mystery

[Wood Doctor]

This is a dandy. A guy brings me his stock Stihl 064 power head and says, "It's not running quite right and seems loud. Please check it over." He leaves.

Next morning I removed the shroud and noticed a loose muffler, hanging on by a thread or two. From the front, the lower left bolt nearest the clutch side was missing, the lower right bolt was very loose, and so were the two short bolts at the top. The front casing of the muffler was somehow tight, but the muffler was loose from the cylinder. I removed those three outer bolts and the muffler fell off in my hand. Both bolts that hold the muffler to the cylinder were also missing completely and so was the exhaust gasket between the muffler and the cylinder. I bolted it all back together and replaced the three missing bolts and the missing gasket. Compression is good, and the engine started OK and runs fine.

The mystery question I have is where on earth did those two bolts that squeeze the gasket between the muffler and the cylinder go? How did they manage to come completely out and than drift into thin air? Through the exhaust port? Seems a bit small for an M5 x 16 bolt to get through and even if they did, wouldn't the operator notice the bolts exiting out?

Forum, please advise and discuss.

 

[kspakland]

If it was my saw, I would blame it on the space aliens.
They refuse to leave me alone and mess with me all the time causing weird unexplainable things to happen.

 

[RED-85-Z51]

Ive seen this on an 064 and a couple 066/660s

Sent from my LM-G820 using Tapatalk

 

[Wood Doctor]

Bottom Line: How did the two bolts holding the muffler to the cylinder disappear on their own? Is that possible when encased in an enclosed muffler, even if loose? That's what happened and that is the mystery.

 

[drf255]

If it was my saw, I would blame it on the space aliens.
They refuse to leave me alone and mess with me all the time causing weird unexplainable things to happen.

Best answer

 

[L34]

Never in there?
Front bottom bolts only to hold on?

 

[Bob Hedgecutter]

Just because it is stock- or rather was stock- it don't mean it ain't been messed with, just factor in the human element to the equation and the puzzle is solved.

 

[Wood Doctor]

So, you guys are saying that the saw never burped the two bolts out the stock exhaust port? That means somebody got in there and removed the two bolts holding the muffler and the gasket to the case and then put it back together with none on board?

Seems reasonable and I must agree. It's a bit tricky to bolt that gasket and muffler back in. Not many saw owners can handle something that tough because they lack the patience and/or the skill. He might have tried and then said, "Forget it." (along with a few other verbal expressions)

 

[Mad Professor]

What about the muffler bearing?

 

[Vintage Engine Repairs]

I ask myself this when I drop a small part. It lands right by my feet and some times I can hear it, yet it’s no where to be seen! It disappears into another worldly dimension, never to be seen again. Parts are only safe from this alternative universe if they are in a magnetic parts tray or correctly installed. I bet that’s what happened here.

 

[Mad Professor]

I ask myself this when I drop a small part. It lands right by my feet and some times I can hear it, yet it’s no where to be seen! It disappears into another worldly dimension, never to be seen again. Parts are only safe from this alternative universe if they are in a magnetic parts tray or correctly installed. I bet that’s what happened here.

Circlips............

 

[Wood Doctor]

I forgot to mention that when I removed the muffler, the front panel was still stuck tight when the muffler dropped into my hand. Had the two bolts been there loose, they would have bounced around inside the muffler like a salt shaker. Nothing was there and neither was the gasket.

Several have told me that loose, inside muffler bolts will likely not come completely out by themselves, Engine vibration may loosen them if not tight enough initially but never completely remove them, especially an M5 x 16 pair.

 

[BuckthornBonnie]

I’ve had them completely fall out into the muffler, yes. It is rare but does happen. I’ve also seen where guys have missed the exhaust gasket on one side, forgotten the gasket, and only put one cylinder-side screw in.