Went to cut the slab rack and all of a sudden my 576 got louder than it should be. Lost one of the bolts holding the muffler and gasket in. Other side was loose. I've got the replacement now is there a loctite product of any value or should I just track down a split washer to fit? It was kind of a bummer got a Good look at the piston and its got just a little scoring on one side, but she still runs fine.
I don't know if any thread lok brands will hold up to the kind of heat made in a chainsaw at the cylinder. Especially on the exhaust side. You may have to slightly bugger the threads about a 1/4 of the way up from the start. That's what I've had to do on MANY mechanical things that I've had trouble with over my few years on this world. This is all assuming that the "latest and greatest" chemical formulation has not been updated to my limited knowledge in the past 30 years.
Again, anything is possible!
I normally use the toughest loctite for rhe exhaust nuts, snd it does help "some".
Buggering up the threads is cheaper and holds better.
That is a real problem with steel screws in aluminum in a very hot environment. Does Husvarna offer a locking plat to go under the bolts?
Yeah the steel and aluminum thing isn't the best. Wish there was a better solution.
Might be off label use, not that should scare you, but they make a retaining compound called 609. I use it to hold high speed bearings in place, 5,000 rpm, on my moulder. It's not cheap, but it works.
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I have had good luck with Loctite 2422 its rated for 650 degrees on exhaust bolts we were having trouble keeping tight.
Blue loctite may hold, red loctite will if the blue won't, may have trouble getting it out later if you use the red, it will hold.
I think all I've got is blue, I'l be passing through the city this weekend and check the auto parts store on my way by.
Before you get it all glued together you might try the serrated Belleville style washers Stihl uses .If a Torx head bolt would fit those would maintain a tighter grip .You could buy these through a Stihl dealer and likely at Northwood saw which is on the net .
609 is rated to +300 F. The real key here is to use the loctite primer as it will allow bonds to non ferrous metal, ie aluminum and stainless plus a shorter cure time. 609 is my go to number for permanent bond. It has a 3000psi shear strength and a .005 gap filling ability. Don't remember the number of the primer. It is basically acetone with copper mixed in. When it first came out the sales person said you can just bore your bearing housings to a slip fit -no more interference fit and use the 609. While true I just couldn't break old habits of training. I used it one time when pressing a bearing in a housing and halfway in the heat from the friction set it up right now. A 10 ton press couldn't budge it. oops!
The red is a real closes thing to permanent .It takes like 400 degrees to release it .Oh it would hold the muffler bolts in but they may not come out again .
BTW you can get an assortment of Belleville serrated washers,stainless steel from Amazon for around 14 bucks,200 count I think,metric sizes .
If it wasn't for 609 loctite My sawmill operation would fall apart.
I think red loctite is all thats holding the front driveshaft in my winchtruck, for the last 5 years anyway. I don't look forward to putting new u-joints in it someday.
Trust me I've used red Loctite on a lot of things .I wasn't bad mouthing it .Fact I've used a lot of Loctite products .Loctite 5900 is the most widely used gasket RTV in the entire world as one example .
So i had to go rummage in my toolbox and found my loctite product selector pocket guide- This would be pre internet technology. There are 4 red loctite products, three green and two blue so referring to them by color is good enough for the individual who knows what he is familiar with but if you are unsure of the application I would advise to search the loctite website for more information .
Oddly enough, the blue loctite comes in a red tube. Wasn't always that way, but it can trip you up if you're not careful.
Recently I got some that is in paste form and has sort of a syringe type applicator. Nice alternative to the liquid, depending on the application. They really offer a lot of different formulations now, so there's usually something that will work for extreme or unusual circumstances.
I just wish the blue loctite still came in a blue tube, but maybe that's just me.
I'd Def stick some red loctite in there, the only thing that's gonna happen is it won't work and you'll be back to square one. But maybe it will.
Stihl has steps on their bolt hole shoulders I just noticed when playing around with an 038, I haven't ever seen anything come loose on these old saws.
Maybe you could take a narrow chisel and knock some steps into the shoulder, pointing in the anticlockwise direction slightly.
That's the idea of the washers .I researched them and they are listed as a conical spring washer ,Stihl part number 9331 630 0120 .All you have to do is Google the part number ,the search engine will find it and prices are all over the place .
I know for a fact they work .The problem is with a lot of repairs they get lost and never reinstalled .Then of course over time the parts rattle off .
If the spring washers really work, go for it.
As far as Loctite...I had a steel spark plug insert into an aluminum head. I used red Loctite for that and the head just got too hot; I'd take out the plug and the insert would always come out with it. I bought Loctite 2620 and that was the end of the story.
I think if you used that on your muffler bolts you could get them back out with a propane torch, but I don't think it would be fun.
Kevin
Does the original manufacture have a torque spec for these bolts? I am guilty of ignoring torque specs and saying "that feels tight enough". Also many factory repair procedures state to use new hardware as threaded components become stretched but is another instruction I frequently ignore.
Quite often the fastener doesn't have the same elasticity that it had prior to use. Usually, from the heat that it's exposed to. Some are more resistant than others, some less. Think of how an improperly ground chain cutter tooth is. It tends to change the Rockwell hardness.
Well if you're talking about spark plug inserts that's a horse of a different color.The best ones are made by "Time Serts " .Fact Roush racing uses them exclusively on every Ford Racing engine they build .However I do have one somebody screwed a straight threaded insert in that does back out.It's of little concern as it's a shelf queen .Not a pretty one either .
As far as torque specs on fasteners ,they can be found with a Google search .
Time Serts are great and so are their prices(high). They use really obscure taps that you can hardly find and a special tool to install. No thanks unless I'm building racing engines. The insert I used came from a NAPA set. Can't really blame the insert if it comes back out with the plug....other than there was no mechanical provision to 'lock' the insert in place like some other inserts have.
Fasteners do stretch and if Stihl says to replace them with new, you should heed that. That's especially critical on head bolts for large engines.
Kevin
Although I've never done it there might be a method to crank in a straight thread insert to work .Firstly there isn't much "meat" to thread on a chainsaw cylinder .However if you could cut the hole and use perhaps a spiral point tap but don't run it clear through you might get a wedging action on the partially finished threads on the base .
In one of my tool boxes,which ever one it is have some inserts that Ford once used on cast iron V8 engines .They required a tool to screw them in and the install tap was real odd ball super fine thread much like a spiral point tap .These were discarded when the big iron engines went the way of the passenger pigeon into history as well as infamy .
Went through the hardware store washer assortment, holes in the muffler were to small diameter to use them, too much fiddling FWIW and I haven't been anywhere to get the correct loctite product.
I went ahead and put it together with the new screws snugged up as much as I dared and the muffler loosened up after about ten minutes, brightside is I only sent one screw to never never land in the grass ::)....Have a spare, but not going to try again without loctite. Next time I get to town, unless I get lucky with the local mechanic who might haved some on the shelf.
You're not gonna get those special Stihl spring washers at a hardware store. I think it's worth the wait to order and try.
I know the Loctite product I recommended earlier will work...but in desperation for not finding it, using another red Loctite product you find at a local hardware/box auto parts store won't work either for long.
Kevin
I've found serrated spring washers on E-bay but they want a kings ransom for them .The Amazon deal for 14 bucks for an assortment of 200 in varied sizes doesn't seem too bad .I have no idea how much they would be from a Stihl dealer .I know often a dealers prices is less then the flim flam flea bay sellers .
As far as a 5 mm spring washer those are easy to find but are not serrated .Better than nothing I suppose .
I suppose you could put a star washer over the spring washer and get close to the holding power with a large headed Torx screw .BTW not all Stihls show a spring washer,just a Torx head screw .Wow lots of options just to hold a muffler on .
Local mechanic had a little loctite peg board display so I've got the red stuff. I still might wait til I get to the city to see if the stihl shop has those washers might be better to use both. On a plus I did get my 7900 out of the shop so I have another saw running that runs a 24 inch bar. So the Husquvarna can sit a while, and maybe get the slab rack cleaned up.