Stihl 200t muffler bolts stripped

[trees4est]

We've got a 4-year-old 200t that we can't get the muffler to stay on. The bolts kept vibrating loose, and I think at some point one of the guys overtightened and now the bolt holes are stripped. You can get just a little tension but the muffler shakes loose again immediately. The dealer says they can't fix it, because there's no room to drill or tap it out. Thanks for any ideas on getting this thing back on. I don't care if it's permanent, really, because it's useless otherwise. I can't really find any high-temp glue that seems like it would work.

We actually had another 200 die last year from running with a loose muffler; it's funny but I searched the forum and couldn't find anything (not that the search function is that functional). I'm going to try and rebuild that one myself as a project. Should I go to the beg for manuals thread for that one?
Thanks!

 

[tolman_paul]

I'm not familiar with that cylinder, but I'd be suprised if there was so little metal in the casting that you couldn't put in a heli-coil.

With the temps an exhaust runs at, there is no adhesive that will work in the application. The only methods I can think off that will work are to helicoil, drill and tap for a larger dia bolt, heli arc up the existing hole then drill and tap it.

The helicoil is my preferred method, it's the easiest and it's the best as your bolts will be screwing into steel, not aluminum.

 

[Fish]

Helicoil is the recommended way to go, there is usually not enough meat to go oversize.

 

[trees4est]

The mechanic at the dealer told me that helicoils wouldn't work, though I can't remember why he said that. It seemed like the best idea to me. It may have been because the depth wasn't deep enough, or the drilling would be too difficult. I don't know, this was months ago. Would you have to take it apart enough to pull the motor or could you drill down through the body openings? I don't know how precise you have to be, though I know you can't drill any deeper at all.

 

[Walt41]

Can you notch tig a couple of studs on it? At least then you would still be able to remove the muffler if need be.

 

[jus2fat]

If you have quality machine shop nearby...I'd be amazed if they either can't fix your saw...

or can't send you to someone that can..!! That's what I'd do anyway....Let a Pro do it..!!

J2F

 

[trees4est]

If you have quality machine shop nearby...I'd be amazed if they either can't fix your saw...

or can't send you to someone that can..!! That's what I'd do anyway....Let a Pro do it..!!

J2F

I hear ya, but that's part of the problem. The dealer said it would run about 300 in labor to break it down and put it back together, and on an older saw it's hard to justify the cost.

The idea of welding on studs is interesting, though I don't know how hard it would be to get a bolt on snug down in the muffler hole.

Sorry, that sounds kind of dirty.

 

[lone wolf]

Dealer is a liar, it can be Heli coiled or oversized tapped out to the next SAE size the Heli coil is a much neater job.BTW I have done this a few times.Then loctite it in with the red.

 

[jus2fat]

I hear ya, but that's part of the problem. The dealer said it would run about 300 in labor to break it down and put it back together, and on an older saw it's hard to justify the cost.

I understand your feelings...however I think your dealer is BSing you bigtime..!!

$300 is a total joke..!! IMHO

Take it to a quality machine shop for a quote..ya got nothing to lose..!!

J2F

 

[Lignator]

pics?

Do you have any pictures? That might help shed some light on it. I would recommend self locking helicoils. You can buy them through McMaster for pretty cheap. With the self locking inserts you don't have to torque down as hard to get the bolts to stay put.

How about threadlocker or grap filling retaining compound?

Another trick might be to try self tapping screws that are oversized (like the next english size for example).

 

[MHouse1028]

i agree heli coil..have a few saws with heli coils and never had another prob.if not i think i have a couple good jugs and blocks for a 200t let me kno if it's a worst case scenario...good luck

 

[THE PLUMMER]

I haven't done this with a 200t specifically but we just went to the next size tap in standard from metric. different thread pitch plus use the special loctite thread locker for cylinders. As the heat will just soften red or blue loctite. There is also a product called DEVCON titanium puddy that we have used to repair or custom shape intake & exhaust ports or repair water jackets . It was tricky on the exhaust sides sometimes. I have a chart, if you can post the thread size and pitch i can find the next couple sizes. it'll list percent hold strength and thread depth options.

 

[jltrent]

If nothing else J. B. Weld.

 

[pgg]

I've had 020/200T's the same, just tap the stripped 5mm bolt holes for new 6mm allen head bolts, all easy and kosher. Dealer is a muppet

 

[Cutter1]

Just buy the right size. That size is used on all the saws on all fasteners.
Wont be the only time you need it.

 

[tolman_paul]

I hear ya, but that's part of the problem. The dealer said it would run about 300 in labor to break it down and put it back together, and on an older saw it's hard to justify the cost.

The idea of welding on studs is interesting, though I don't know how hard it would be to get a bolt on snug down in the muffler hole.

Sorry, that sounds kind of dirty.

Yes, if the cylinder was pulled from the engine, sent to a machine shop, the holes were welded up, then the cylinder was mounted on a mill, the exhaust face was machined true, the holes were drilled and tapped on the mill, then the machine shop sent it back to the saw shop, the saw shop re-installs the cylinder with a new base gasket and tests the say, maybe it could become a $300 job.

Usually when a shop comes up with a rediculous quote it's because either they don't know how to do the job, or they don't want to do the job.

You're just mounting a muffler, it's not like you're making a bearing pocket for a crankshaft which is a high precision job. A competent mechanic could do the job in a drill press and if he charged more than an hour labor something is wrong.

A generic brand helicoil set runs you ~$25 for tap and a 10 pack of the inserts. Anyone half competent should be able to hand drill the hole close enough for muffler work.

 

[THE PLUMMER]

I have also tig welded inside ports on larger cc bores (125cc) to repair or change. So welding this is not out of the question, just requires a pulse tig and many steps to keep heat fractures from occurring. I still think the larger tap is the trick. From 5mm either .8 75% thread lock or .9 60% thread lock thread pitch, the next sizes are
12-24 75% #16 drill
5.5 mm x .9 75% 4.6mm drill
12-28 75% #14 drill or 12-24 @ 60%
6mm x 1.0 pitch 75% 5mm drill
1/4-20 75% #7 drill
6mmx.75 pitch 75% 5.25mm drill
1/4-28 75% #3 drill
7mm x 1.0 pitch 6mm drill

plenty of choices with the material you have to work with. you might have to grind off the tip of the tap to get full depth threads, obviously after you've already made a pass to start the threads.

 

[trappermike]

I agree with Lonewolf your dealer is full of s**t, he doesn't have the skill to do this simple repair or he wants you to buy a new cylinder or machine,I wouldn't let him touch it,take it somewhere else.
I too agree that heli-coils are the best repair,properly done they are better than original threads and adding a little red loctite(As Stihl does in some cases) will help too. I've never seen a case yet where there wasn't enough metal to install heli-coils. Also use new studs or bolts and nuts,check them periodically for tightness. It's really a basic simple repair,the key with heli-coils is they must be installed properly!

 

[trappermike]

Any decent mechanic should be able to install both heli-coils with new fasteners in an hour or less.

 

[pgg]

Any decent mechanic should be able to install both heli-coils with new fasteners in an hour or less.

helicoils and stuff totally unneccesary, just tap in the next size-up bolt which is 6mm. Tons of room there