Help Stripped Crank Snout Threads

[ztsmith86]

So I was installing my Harmonic Balancer and I won't go into the details, but I have completely stripped out all my threads in my crank snout. There is no material left to even re-thread the M16 threads. Does anybody have any suggestions? I have a few ideas myself, but I really need suggestions. This is the last things before my engine install is complete. Thanks for any help .... I'm already down in the dumps about this :(

[KARBON]

Helicoil

[toml_pa]

You have 2 choices, replace the crankshaft or repair the threads. Obviously the first choice is a last resort option. So the question is how to fix the threads. The only way I know of is with HeliCoil Screw Thread Inserts.
You will have to have access to be able to drill the damaged threads out so hopefully the engine is not in the car yet. If it is and you don't have clearance for a drill, you might be able to loosen motor mounts and lift it up enough. Of course the front fascia and radiator would have to be removed. The hardest part will be drilling the hole straight and hand taping the hole for the helicoil. The only other problem I see is that helicoils are usually about 1.5 times their diameter long which means you will only have about 1" of threads. I am not sure how deep the original threads are but isn't the crank bolt fairly long? You might be able to get longer ones or use 2 and stack them. If you know or can find any machinists that have experience with helicoils it would be a good idea to explain your situation and get some advice or better yet pay a machinist to do it. Hope this helps.

[ztsmith86]

Ya my engine all put together in my car

[grocerygetter]

I would guess stock crank? If so, helicoil and I personally would pin it to make sure the accessories wouldn't work the threads out off the pulley. But an honest question, will a helicoil hold the kind of torque you need to put on that bolt?

[94guy]

man that sucks

[ztsmith86]

Is the stock crank forged, rolled, or cast?

[toml_pa]

Originally Posted by grocerygetter

But an honest question, will a helicoil hold the kind of torque you need to put on that bolt?

I would say yes. The ones I have used were stainless steel as are the ones in the link above. I would be more worried about the new threads in the crank that the helicoil screws into or the threads on the bolt. That is why I suggested trying to get longer helicoils or seeing if it is possible stack them. I wouldn't try torquing it with only 1" of threads. Like you said, pinning or even double pinning it is a real good idea.

[10aSSee D]

Originally Posted by ztsmith86

Is the stock crank forged, rolled, or cast?

Pretty sure it's iron.

[blake-b]

A quick google search says helicoils can be stacked

[zarenski]

I not sure how much material you have to work with but can you drill and tap to the next size larger and get a new bolt? The helicoil would make me nervous.

[Eric Baker]

Yeah I would drill it and tap it to like an 18mm or something, then get a nice bolt from ARP. I wouldn't trust a helicoil for the 240+ftlb the bolt gets torqued to.

To do it in the car won't be bad. Once you remove the bumper, radiator, and move the A/C condenser out of the way, you have great access to the front of the crank.

[sschevybear11]

helicoil will work and don't stack them. I always understood thread depth won't be any stronger then the diameter of the bolt width. You could use a threaded insert to be sure but you have to drill it out pretty big and may weaken the crank snout to much.

[ztsmith86]

I've heard the heli coils are really hard to install. The snout has a blind hole .... The threaded part is 3 inches deep inside the blind hole