rcinspired

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The pitts muffler on my 60cc keeps falling off. i tried copper silicone instead of gasket and places permanent thread lock on the bolts. no matter what i do. the muffler comes loose.

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STUKA BARRY

GE-106 Red RTV works great. A thin layer on the engine exhaust flange, and a thin layer on the gasket that mates to the muffler. Torque the bolts and run a thin bead across the muffler bolt heads. let sit over night, problem solved. Make sure the engine exhaust flange and muffler flange are clean (wipe with alcohol).

Tired Old Man

My Feedback: (1)

Depends on how many times it has already happened. A close inspection of the cylinder thread bosses is in order to determine if they have been damaged by a loose mounted muffler. You can get away with it once, usually, but if the muffler is not well secured after that the previous damage is expanded, with each following event making things worse. It gets to a point where correcting the damage will be the only way to keep a muffler on. Helicoils, tapping to the next laeger,, or two sizes larger screw, or cylinder replacement.

av8tor1977

My Feedback: (6)

Question... If you had a good cylinder you wanted to save that had ruined muffler holes, could you have them tig welded shut and make new holes, or would the heat distort/ruin the cylinder bore?

AV8TOR

dant-RCU

My Feedback: (3)

I have used this on three gas engines with pitts style mufflers and it work great. No more loose, leaking or falling off
mufflers. Just completed one on my G45 last weekend. Takes me about 20 minutes (max) to do it.

http://www.rcaer.com/userfiles/file/...0them%20on.pdf

Dan

All Day Dan

My Feedback: (5)

Steel bolts into cast aluminum threads is a disaster waiting to happen especially in the high vibration environment our engines produce and the constantly increasing loads our mufflers put on them as the mufflers continue to grow in size. Any kind of locking device or material is essential. Given that, once a muffler gets loose the threads are usually destroyed. About the only way to fix that is with Helicoils or their imitations. It’s not a savory thing to do but it works. Just make sure that the screws don’t come loose again. Dan.

Antique

My Feedback: (4)

Best way to attach aftermarket mufflers to Zenoah engines..
Since there are no thread in the cylinders the bolts used are square on the cylinder to fit into square pockets in the cylinder...Hex nuts in the pockets don't work for very long, not enough surface contact...
Get some steel rod that just fits into the mounting holes in the muffler..Drill through with a .196 drill and cut off flush to the outside surface of the muffler...Cut the stock square head muffler bolts about 3/8 longer than the muffler surface and run a 5mm .8 die over the end...Throw the gasket away and use Permatex Ultra Copper on the surface of the cylinder....

DadsToysBG

My Feedback: (35)

I have used helicoils on mine in the past and they have worked great. Very easy to do. Dennis

av8tor1977

My Feedback: (6)

I'm still curious about the welding question...



AV8TOR

Antique

My Feedback: (4)

Depends on the skill of the welder...Most welders don't want to weld an oily surface....

captinjohn

Try it on a extra cylinder like a homelite...whatever. Burr out where you plan to use the weld for build-up. Clean before and after burring. Also take a few measurements of the bore and record them. Do your welding. After you done with the welding...take some more readings to see if the bore disstorted. A tig welder would be the best I think. Sounds like a worth while experiment to me. Good Luck....Capt,n OH...dont know...but maybe a heatsink in bore when welding may be good????

aegis

Prior to mounting a muffler, I clean the threads on both the head and bolts really well with aerosal electronics cleaner, the type that isn't designed to leave an oliy residue. A little bit of thread locker and no problems.

Dan

captinjohn

Sometimes the muffler or the engine mating surfaces are not flat. Check for that with a strait edge. Sometimes you will need to square things up using a mill. Also some exhaust mufflers that have weight off to the side ...will need to have a brace added so viabration cannot set in. There are photos showing how this is done. Capt,n

Lnewqban

Avoid welding next to the cylinder machined surfaces; heat and precision don't get along well.

If enough aluminum is there, tap a higher size and replace those silly bolts by stub-bolts.
Let the steel nuts take the beating, instead of the soft aluminum threads.

Steel into aluminum threads are a one shot deal, more than that and the proper fit is gone forever.
For extra insurance, fix the position of the nuts with tie-downs, conformable washers or any other mechanical method.

Eliminate soft and thick gaskets.

Soft-support the muffler at its opposite end if possible; that liberates the bolts from a good deal of stress.

mike31

My Feedback: (67)

What's wrong with heli-coils?

Tired Old Man

My Feedback: (1)

Nothing.

JVB

My Feedback: (2)

Drill holes through the heads of your cap bolts and wire them.