I have a late 1990s Sears Craftsman string trimmer, model #358.798530. It runs great when I can keep the carburetor attached to the engine. The two screws that hold the carburetor in place (circled in the photo) keep backing off. I was going to use the blue Loctite on the screws. Is there any reason I should not use Loctite? Or is there a better solution?
String Trimmer Carburetor Keeps Coming Loose
- Thread starter kc27
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Hammermechanicman
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Get a couple small zip ties and cut pieces the same length as the holes are deep. Put a piece in each hole and install the carb. Zip ties will fix the wallowed out plastic threads.
Tiger Small Engine
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Good suggestion. Loctite will not fill the void if plastic is stripped out. I have never tried this, but will remember it for the future. Have you ever tried zip ties for stripped out bolts going into aluminum or metal?
Hammermechanicman
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I have used copper wire in damaged aluminum threads.
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Gentlemen, The problem is created by techs. When self tapping screws are installed in plastic they create their own threads. Same happens with aluminum and steel when self tappers are used. If you don't follow a known method when reinstalling them you just keep creating new threads until the screw no longer holds. Most of these 2 cycles uses a plastic carburetor intake adapter that should be replaced once you strip out the threads.
To prevent creating new everytime, you place the screw in the hole and instead going hog wild and tightening the screw you first turn it as if you are removing it with a slight downward pressure. When you do this you will feel when the screw threads drop into the hole threads and then you tighten up the screw thus not creating new threads.
As for stripped out threads in aluminum and steel just simply heli coil them provided there is enough material left to do so. Sometimes inserts can be install even in plastic. I have done this on several chainsaws were someone stripped out the holes.
To prevent creating new everytime, you place the screw in the hole and instead going hog wild and tightening the screw you first turn it as if you are removing it with a slight downward pressure. When you do this you will feel when the screw threads drop into the hole threads and then you tighten up the screw thus not creating new threads.
As for stripped out threads in aluminum and steel just simply heli coil them provided there is enough material left to do so. Sometimes inserts can be install even in plastic. I have done this on several chainsaws were someone stripped out the holes.
A friend suggested if the zip tie shim doesn't solve the problem, maybe try filling the screw holes with an epoxy like JB Weld and tapping new threads. He also questioned the design of the trimmer, that screws could not nold a carburetor in place. I countered with the fact a 1998 low end trimmer from Sears was probably engineered to last 15 years of light use before needing replacement. Keeping it in service for 26 years is well beyond its intended useful life.
Thanks, this worked. I ran the trimmer for an hour and the carburetor was still on tight. Previously it would loosen after five to ten minutes of run time