Stripped Thread on a DuraForce Block

I would use a helicoil.

I think Loctite makes a thread restorer, but I don't know how well that works.

i had that kinda prob with my v-series......muffler bolt stripped out, i just tapped the bore for the next size up& a dot of loctite on one end,& dot of never sieze on the other end
lol now i have to do the mount bolts, they shook thier way out too

68 Pontiac said:

I would use a helicoil.

Click to expand...

:ditto::ditto:

I'm going the helicoil route. It's an SAE 5/16" thread on a 9/16" head bolt. I'm not keen on drilling out the bad thread, but I want to fix it right. This 10550 is going for sale after I finish.

I didn't realize how much of a hassle it was going to be taking the motor from a steel to aluminum deck. First the exchange of the mounting plate, then this stripped thread thing.

Taking the plate off again I decided to replace the exhaust and muffler gaskets since they both could take another disassembly. No one has the gaskets. Hopefully, one place does, but it's closed today.

Has anyone else had this problem with the mounting plate bolts? I thought cadmium plated bolts wouldn't freeze in aluminum threads. Hmmm. I will use PB Blaster next time.

What about drilling it one size larger and tapping it for new threads? Since it's aluminum, a slightly larger bolt might just cut the treads for you.

Sean Woods said:

What about drilling it one size larger and tapping it for new threads? Since it's aluminum, a slightly larger bolt might just cut the treads for you.

Click to expand...

I went ahead and bought the helicoil. I want it to last. Tapping the thread for a bigger bolt would require drilling the mounting plate as well.

Thanks to all for the advice!

I had 2 of 3 muffler mounting bolts partly strip on me, my fault... I ended up just buying 2 metric bolts that are just a fuzz larger in diameter (that's technical jargon there). Since it's all aluminium and there was a hint of threads left the new metric bolts actually threaded in and snugged down fine. Certinaly not the "right way" to fix the issue but it worked! Later in life when the muffler needs to be removed it's going to be a bit confusing for myself, or someone else, as to why the SAE wrench won't fit on two of the 3 bolts though!

Update on my junked 10324 donor to the junked 10550 that I got for free.

10550 transplant completed. Did the helicoil, and it worked great. changed all of the exhaust gaskets, de-coked the port, etc.

Put the whole thing together, and after one pull, I have a great running 10550. Actually, it runs better than mine! It starts without a prime warm in low speed! One interesting note: this DuraForce surged bad when I first got it running in August. Now it runs better than any other DF in the stable? The only thing I did was the above plus a little carb cleaning.

If anyone in the southeast Texas area is looking for a 10550, it will be on craigslist by lunchtime.

First major LB repair completed with 100% success.

wooohoooo congrats gcmartin1!!

looks sharp!!!!!!!
got a question,
on the 10323....
which holes bolt the exhaust plate to the deck?is it the ones with the sort of nut embedded in the plate?
going outside to mess with this unit later

2cycled fruitcake said:

looks sharp!!!!!!!
got a question,
on the 10323....
which holes bolt the exhaust plate to the deck?is it the ones with the sort of nut embedded in the plate?
going outside to mess with this unit later

Click to expand...

That's the one, although mine were threaded and had no nut in them. Furthermore, the bolt only entered about 3/4" into the flange.

I just threaded one helicoil into the flange(mount) It works great. The mower is running fantastic with no undo vibration or weaknesses.

cool
glad it worked out for ya i found out the size i needed 5/16 X 1-1/2
found a site for the other stuff i needed, lower exhaust pipe,&plate
, after i get this one running, i'll probably part out my 10227 over fall&winter