Stripped muffler bolt

[rskybiz]

I have a stripped muffler bolt on a Husqvarna 350. Question is is there enough meat to tap it out and helicoil it and if so any recommend size?

 

[woodworkingboy]

Judging by this photo, it appears that there is sufficient room for the next size up.

 

[Tucker943]

Holy melting chainsaw!!!

 

[woodworkingboy]

It seems like vibrating loose muffler bolts was a problem with that model. The guy that posted that photo says that he had some retrofit done at his Husky dealer that was supposed to solve the problem, but it kept loosening up and eventually melted the housing down into the oil tank. Looks pretty serious.

 

[Cobleskill]

He shoulda smelled something wrong, don't ya think? What a mess.

Doing some searching one guy said 288 muffler bolts worked well as they are larger.

Helicoils seemed to all fail. They make a bushing style insert that is good but might be too large to work.

My old 45 had T bolts that hooked in. They worked great.

 

[rskybiz]

Wow that is one ugly!

 

[CurSedVoyce]

Try to find a self tapping screw one size up..

 

[1BUS]

I'd tap and heli-coil it back to the original size

 

[woodworkingboy]

I believe that they make a medium strength Loctite that will work in heat. Might keep a heli-coil from failing.

 

[Jack]

I'd tap and heli-coil it back to the original size

... locking helicoil ...

 

[woodworkingboy]

Wonder what it is that keeps the bolts loosening up on that model, I mean to a greater degree than is normal on saws? Is the muffler particularly heavy? If there is space, you could maybe stick some star washers under the bolt heads to help keep them from turning.

 

[rskybiz]

Cool Jack! Jay not sure but it is a issue with them for sure. First bolts loosened and the local husqvarna saw shop tech said take the gasket out it lasted like that for a year or more without loctite.

 

[oldtimber]

Maybe the helicoil, and stake it like an Ar15 gas key bolt? Tack it with a mig welder? The consequences for not lockin that bugger down seem obvious.

 

[Jack]

Another option worth considering (instead of a mig tack) is safety wire. It's cheap, easy and almost fool-proof:

This is the tool I use ... bought it at the cycle shop. But, they're widely available:

 

[Steve Mack]

And I thought I invented that safety wire thing.

Some of the old Husky's had a little locking plate that closed over both bolts, never had one of those come loose.

I use Keenserts usually on most things. http://www.acmeindustrial.com/keylockinsert.htm A lot better than helicoils, but I'm not sure offhand if they go that small

 

[Al Smith]

FWIW a stripped 5MM hole is the right size to zip a 6MM spiral point tap through .One option could be using a serrated belleville type washer to help keep it tight .

 

[rskybiz]

Will have with all these options a sure fire fix by this evening thanks all!

 

[Cobleskill]

http://www.henkelna.com/us/content_data/84590_high_temp_lubricity_tl.pdf

Loctite that is good up to 600F. New to me. Does the cylinder get hotter than that? Locking a stud into the cylinder would be a good fix. Double nutting is an easy and fairly good method.

 

[Al Smith]

On aluminum cylinder heads on modern automobiles they use stainless steel studs that have a coating of a type of sealant on them .The nuts used have a captive type belleville type washer which allows it to move with temperature variations but still keeps tension on the fastener .

200T Stihls that use an aluminum muffler are noted for having problems rattling the muffler loose .I think more times than not people screw the bolt back in but forget to use the serrated belleville washer that's supposed to be in there .A lock washer really won't do you much good in a situation like that .

 

[Jack]

Ya got me scared, Al! I've never had any trouble with my 200T ... so far. NOW, I gotta go safety wire it.

 

[Tucker943]

Rust. Rust keeps mufflers on. Hate to be that guy to say it though.

 

[CurSedVoyce]

Truth

 

[Tucker943]

I know it sounds completely asinine but when those bolt heads rust up a bit and bond to the muffler itself, they stay put. I know of some retired loggers that used to let their saws ride in the back of their trucks for a few weeks when they bought them new. They swore a little rust in certain places held the saw together better then anything.

 

[MasterBlaster]

I haven't seen safety wire pliers since my flight deck days. Cool.

 

[rskybiz]

Every sportster I have put back together has sat in the rain for that reason before any real riding. That said this saw spent many days in the back of my truck to no avail.
I did get helicoil for it and will wire tie it also.