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Stihl 026 exhaust bolt..

Started by realzed, October 28, 2020, 01:01:30 AM

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realzed

My son's old Stihl 026 had an exhaust bolt (lower bar-side) that I figured was starting to loosen up due to poor threads as it gave me a sinking feeling the last time I had the muffler off and reinstalled it - when it felt like it wouldn't tighten up as well as I thought it should.
He now tells me it has worked it's way loose and I'm pretty sure its because the threads in there are pooched..
What the easiest way to fix the problem?
Do Helicoils work and is there sufficient material and depth in that area to consider one - or is there another option that would be just as good or better?
Thanks - Randy  

sablatnic

Helicoil is fine and the easiest - have done several myself.

Greenhighlander

I have never done it on a saw but have used steel wool in similar situations.

Tacotodd

The steel wool sounds interesting, I'm just not sure 🤔 if it's going to be a better idea or not. Probably because I've never heard of that. Does it work without damaging whatever maybe left of the existing female threads? GH, tell us of your learning of this idea and experiences with it.
Trying harder everyday.

doc henderson

might work.  it will fill up a void in the threads and tighten things up.  helicoil as a back up.  I was running my mill as a demo at a camp a year ago, and my set works kept going off.  i found the + on the battery to be loose.  It would not tighten up.  there are about 3 things attached there including a coupler.  the problem was in the side mount female threads in the lead.  I made a sliver of wood with my knife, and stuck this into the threaded hole, then reinstalled the bolt,  it has worked ever since.  the next step for me is melting lead back in the hole and rethreading.  i think the steel wool may work the same taking the slop out of the threads.  
Timber king 2000, 277c track loader, PJ 32 foot gooseneck, 1976 F700 state dump truck, JD 850 tractor.  2007 Chevy 3500HD dually, home built log splitter 18 horse 28 gpm with 5 inch cylinder and 32 inch split range with conveyor powered by a 12 volt tarp motor

lxskllr

I like the sound of steel wool. It's easy, and the least destructive first start. If it works, great! If not, you're no worse off than you are now. I've used the wood(and various other material) trick numerous times on various projects. Works well.

lxskllr


Greenhighlander

Quote from: Tacotodd on October 28, 2020, 06:23:37 AM
The steel wool sounds interesting, I'm just not sure 🤔 if it's going to be a better idea or not. Probably because I've never heard of that. Does it work without damaging whatever maybe left of the existing female threads? GH, tell us of your learning of this idea and experiences with it.
I worked on a drilling rig for many years and it was a little trick my motorhand showed me early on.  We would do it until a replacement bolt could be found or came with the weekly supplies.   It always worked and I would say it never damaged the female ends threads as we never had any issue with the new unstripped bolt .  I would imagine the steel wool is not hard enough or thick enough or whatever to damage the threads which were usually actual steel. 
I have also used it a few times wood working with good success as well.  
Cheers  

Al_Smith

From the description referencing lower bar side  it could be assumed it's the bolt holding the cover on ?You might be able to drill it out a tad and replace it with an M6 bolt .The original bolt is M5 by 12 .

Tacotodd

I wonder if @realzed has read any more and/or fixed his issue yet?
Trying harder everyday.

realzed

I agree that the steel wool deal sounds really appealing - anyone know how much of it is needed to do the job... like a strand of two of it or quite a bit.  Maybe it depends on how badly the threads seem compromised..
First I've ever heard of anyone using it - but it does make sense and worth a first try for sure, if I can find out more about details about the methodology.. 
And YES it is the muffler cover bolt, lower and bar side..
I know I tightened it up as much as I felt it could handle - but either that wasn't sufficient to get it to keep holding with the vibration or the threads have now given up... 
I'm sure most of us know that sinking feeling when you know a fastener should be getting tight from the number of turns and/or feedback through the wrench - but you aren't getting that sense that you can feel the torque building up the way it is supposed to as you near the point where it should... like "Ugh Ohh.. something's not quite right here" 

doc henderson

could consider a little loctite if you like.
i have never used it, but you have to get it into the threads.  if you wrap it around the bolt I envision it just bunching up.  i would stick strips in the hole perpendicular to the threads, and get the bolt in and see how it goes.  for the amount, I would test the fit and use "just enough"! :)
Timber king 2000, 277c track loader, PJ 32 foot gooseneck, 1976 F700 state dump truck, JD 850 tractor.  2007 Chevy 3500HD dually, home built log splitter 18 horse 28 gpm with 5 inch cylinder and 32 inch split range with conveyor powered by a 12 volt tarp motor

Real1shepherd

Well, I've always been an advocate for steel inserts. And if there's not a lot of surrounding 'meat' use a thin wall insert. Any insert you put in will be stronger than the magnesium or aluminum. Personally, I don't like Helicoils.

And sure, if there's enough meat, just save some money and go to the next largest metric bolts size and tap ya a new hole. I would do the companion bolt hole the same though so you don't have different sizes.

As far as heat from the exhaust....you can reach 450F or so and regular red Loctite may liquefy. So for that you need Loctite 2620. And then as they say in Brooklyn...forgetaboutit.

I can't tell you how many of those little flywheel puller holes I've stripped out. I just tap to the next size and I've never had anymore troubles......

Kevin

Greenhighlander

Quote from: realzed on October 28, 2020, 04:29:08 PM
I agree that the steel wool deal sounds really appealing - anyone know how much of it is needed to do the job... like a strand of two of it or quite a bit.  Maybe it depends on how badly the threads seem compromised..
First I've ever heard of anyone using it - but it does make sense and worth a first try for sure, if I can find out more about details about the methodology..
And YES it is the muffler cover bolt, lower and bar side..
I know I tightened it up as much as I felt it could handle - but either that wasn't sufficient to get it to keep holding with the vibration or the threads have now given up...
I'm sure most of us know that sinking feeling when you know a fastener should be getting tight from the number of turns and/or feedback through the wrench - but you aren't getting that sense that you can feel the torque building up the way it is supposed to as you near the point where it should... like "Ugh Ohh.. something's not quite right here"
You don't need to use too much but def more then a couple strands.  Start small and keep adding until it holds.  Usually just a pinch is enough ( depending on bolt size ) .    I wish I had more details about the methodology of it , but it really is that simple . 

kantuckid

I dislike the idea of what's a non-permanent repair on a chainsaw that's expensive. I suppose were the threads not too buggered an industrial epoxy might be one answer but those I'd consider are not inexpensive choices, so part of that decision is to ask:
 what must come apart to replace it? , how much a new or ebay part will cost? Can I do the repair/replacement myself? so on...
Loctite is a company that sells many products, not just thread lockers and just stuff we see on pegboards in box stores. Some of there not so public products are those epoxies I'm mentioning.
Typical red thread locker asks for a tight thread clearance and isn't intended to make up for a sloppy fit on bad threads. 
 Helicoils are good and can be relatively permanent. Threaded inserts such as Thinserts and other similar products are also good choices. 
The answer lies in how much metal is left to "play with" ? 
Like many folks I've done my fair share of "Farmer fixes" but a chainsaw asks to be done right the first time! Wood slivers glued into wood is great, into metal, well not so great? :D
It's not like your stranded on an island and got to "Mcgyver the thing"!  ;D 

Kan=Kansas;tuck=Kentucky;kid=what I'm not

doc henderson

I agree with a permanent repair.  this can be limited by skill, cost, time.  so I think we were relating a number of options to choose from.  the wood sliver I used was in the wilderness and used to shim a bolt into partially stripped lead female threads.  The repair of using a torch and heating up the side post and dripping molten lead in, sounds like a bit of a crap shoot, and I have never done it.  prob. take and hour or two, and my field fix is working fine...until it does not.   :D  .  if it were a bar stud, I would replace it.  an exhaust bolt may never be touched again on a saw this old.  sounds like he got it snug, but it loosened up over time.  thus the thought of loctite with the steel wool.  fun to banters ideas around.   smiley_beertoast
Timber king 2000, 277c track loader, PJ 32 foot gooseneck, 1976 F700 state dump truck, JD 850 tractor.  2007 Chevy 3500HD dually, home built log splitter 18 horse 28 gpm with 5 inch cylinder and 32 inch split range with conveyor powered by a 12 volt tarp motor

Al_Smith

As far as inserts a company called Time-Sert is probably  the best made .In the manufacture of automotive engines on occasion a tap will break, a piolet bit will fail or be off sized .These inserts are what is used to make those repairs and Roush racing uses them on every race engine they build .Problem is the taps and drills and the inserts are too costly for the average hobbiest .I'm not a fan of actual heli-coils either .

realzed

Lots of great ideas and thoughts - Thanks for all of this!
I am going to take both of our saws apart and clean them up for Winter storage soon, as it is now past the end of our 'firewood season' around here, and I intend to take a better look at the bolt itself and the threaded area it goes into, to try and determine just how much (a) work is involved) (b) money it could entail and (c) which of the suggested fixes looks like the best route to go all things considered..
Thanks again..  Randy

Real1shepherd

Time-Serts are the best and they're also crazy expensive too. They use really hard to find taps and installation tools. I had to go to a machinist once to find a tap Time-Sert was using for an insert. For example, you could go to Fastenal and buy two Time-Sert inserts along with their tools and be out $80+. That's over $40 a hole.....

For the last ten yrs or so I have been using E-Z Lok thread inserts. You can fashion a screwdriver easy to install the inserts....don't need their tool.....and their taps are standard taps easy to find for the inserts. They do metric and US and combinations etc. They also have thin-wall inserts. I can say absolutely nothing negative about them.

As far as skill....this is an easy one to learn....don't be put off by it. In mag and aluminum you don't need a drill. Those tap holders found in tap & die set make for perfect hand drilling. Go slow and in no time you have a nice perpendicular hole ready to tap for your insert.

Kevin    

Al_Smith

If you are going to use an insert you have to tap the hole out over sized which is why I suggested just going to M6 .I've done it a number of times .Lots of times you can run a spiral point right through a smaller hole if it's wallered out enough .Standard 4 fluke taps are not what should be used on non ferrous metal unless that's all you have .With a "gun point" tap you can use a standard bottoming tap to clean up the bottom threads .although a partial thread or two would pretty much lock it in place .

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