So Im putting the silverado motor mounts on the LM4 alum. engine this afternoon, doing the second pass at 30lbs and one bolt didn't feel right...pulled them all back out and checked everything over, appeared to be ok...so started all the bolts back in, reset wrench to 20lbs for a first pass. Turned the three others in, clicked as normal. The fourth, well...it turned in...and slipped. So I pull it back out expecting to see rounded threads...but ohhhh no, they simply fell out of the block... I have a solid half inch little spring of threads! I couldn't believe it. Has anyone every seen or heard of such a think happening? Factory torque spec is 37 and I never even got close! There is NO way this should've happened. Basically I have two options, either I'm gonna timesert all 8 mount holes with stainless inserts, or I'm gonna put off the swap till next summer and buy a new block and switch everything over, and it will NOT be an aluminum block. Not happy with the situation. Any opinions or thoughts from anyone? I just don't understand why this would've happend?

 

Check the other threads and just put a helicoil in it. Happens alot with aluminum. I've seen this happen with a 4.6 cadillac engine. Had to put inserts in all the head bolt holes in the block.

 

So you had problems with just one bolt r all of them?

 

you tq the motor mount bolts?!?! i just installed them as tight as my 3/8" ratchet would get them

 

Just tap it a size bigger..Dont really see the big problem here

 

X2 ^^^^ r just run 7 lol

 

helicoil

 

This is what I'll probably use, might even do it to all 8 because seems like a better idea to be bolting into stainless steel than aluminum anyways...

http://www.timesert.com/

Just kinda ticked that it happen, shoot I wasn't even pulling on it...