Author Topic: Block Crack (Read 1374 times)

Tom Dugan · « **on:** March 05, 2006, 12:35:25 PM »

Looking for your advise on repairing these small cracks. Have thought about J&B Weld but not sure it would bond into the crack very well. Is Alumiweld a possibility? Or, is this a problem at all?

The engine is a ST 46 that is in otherwise great condition. Is this a common problem? As always, your advice is welcomed.

I failed to mention that both side are cracke in the same place.

Thanks...Thomas

Bill Little · « **Reply #1 on:** March 05, 2006, 12:51:06 PM »

Hi Thomas,

I have made similar repairs with standard (not the quick set) J B Weld. They have held up fine. As you know, getting the area clean is of utmost importance.

That is a rather low stress point area, so sealing the crack is about all that would be needed.

Did you get my last email? Phone number?

Thanks!

madhitter · « **Reply #2 on:** March 05, 2006, 04:40:52 PM »

I agree regular JB Weld is the way to go. I was afraid to use it for a long time. but is great stuff for many of our needs. (Older is wiser I guess)

Steve B

Edit: The absolutely clean part is very important. SB

Bill Little · « **Reply #3 on:** March 05, 2006, 07:30:52 PM »

Thomas,
One thing I remembered is to heat the JB Weld with a heat gun so that it thins a *little* bit and will be easier to force into the crack. Sealing the area is all that will be needed. If you put the spray bar in place, covered with melted vaseline, the hole will not get any in there and the spray bar will not stick in place.

RC Storick · « **Reply #4 on:** May 17, 2006, 06:32:26 AM »

This is not what some people like to hear but. I have always felt that when things like stress cracks happen it is best to replace the part. Buy the best the first time it will save you money in the long run.

RandySmith · « **Reply #5 on:** May 17, 2006, 09:47:13 AM »

Thomas

JB Weld is NOT going to fix the case, it will break again or the epoxy will get soft and come loose, depends on where the crack is.
Where is the case cracked at?
The only REAL way is to have someone weld this crack shut. Using epoxy is just a temporary fix

Randy

Bill Little · « **Reply #6 on:** May 17, 2006, 10:05:43 AM »

Hi Randy,

The cracks are where the NVA or keeper for the R/C carb goes. At the top of the holes on the intake throat. You know, where a lot of guys fill with epoxy when they drop the sprinkler system and put the NVA through the case.

Bill <><

RandySmith · « **Reply #7 on:** May 17, 2006, 11:34:41 AM »

The cracked case at that point, where the carb mounts is almost always broken because of a crash.
I have seen this about a hundred times or more in engines. many times the crash will also warp the front of the case.

I have tried many times to repair this crack , but so far the only thing permanent has been to weld it

Randy

Tom Dugan · « **Reply #8 on:** May 17, 2006, 08:51:26 PM »

Thanks All for the more recent advice. Since my original post, I sent the engine to Frank Bowman to be checked and rebuilt. Since the cracks are not actually in the round well that the venturi slides into but are in the flat spot where the venturi slide bolt goes, Frank recommends mounting the venturi normally and sealing with silicone. I'm comfortable with doing that.

Since I have several other ST46s I will have the venturi portion of the block milled down and the spray bar hole drilled trough. I believe Tom Lay and others do this also.

This is still a good engine with many flights left on it. If there is a simple fix then it seems a waste to relegate it to the parts bin and it won't be

Author Topic: Block Crack (Read 1374 times)

Tom Dugan

Block Crack

Bill Little

Re: Block Crack

madhitter

Re: Block Crack

Bill Little

Re: Block Crack

RC Storick

Re: Block Crack

RandySmith

Re: Block Crack

Bill Little

Re: Block Crack

RandySmith

Re: Block Crack

Tom Dugan

Re: Block Crack