While helping my son-in-law for the second time replace his engine in his Mitsubishi POS, (long story), we used the bolts supplied with the new engine to bolt on the flywheel. Well as it turns out, they were for a flex plate, and we pulled the threads on the crank.

Do you think helicoils will work, or do I need to thread them for the next larger size?

I am just not sure that the helicoils will torque up to specs.

personally i wouldn't use heli-coils, thats not something that i would want to chance coming loose while driving, but thats just me

try one heli coil and see if it will torque,if not rethread:D

better you than me:eek: not fun to be where you guys are....good luck:usa:

try a search on this. it was brought up last week. someone even said that they are a legit way to fix aircraft.

Drew

Same thing happened to me. Was installing a flywheel on a 350 and the dealership gave me flexplate bolts instead of flywheel bolts.

When torquing the 2nd bolt I felt the threads let go.

I panicked.... did I destroy the crank shaft? No. The flex plate bolts only damaged the first 2 or 3 threads. The correct flywheel bolts are so much longer and there was plenty of thread remaining in the hole for me to fully torque them down to specs.

Also, Loctite makes a thread repair system (available at NAPA) that can withstand over 100ft lbs of torque. Before I realized my situation wasnt so bad I had purchased this thread repair kit after a few machine shops suggested it to me. Luckily I never had to use it.

Here it is...


http://www.crlaurence.com/ProductPages/frameGen.asp?Product=28654&ProductID=12745


http://www.loctite.com/datasheets/tds/Form-A-Thread_Stripped_Thread_Repair_Kit.pdf

check the damaged thread depth, if its only a few threads run in a tap to clean them up. then locktight thread repair and pay attention to the torque values when you do it up.

well to install a helicoil you would need
to tap it any ways
so why would you not just tap it to
the next larger bolt size ??????

ps I have used the lock tite repair
system and would not recomend it
for the smaller bolt diameters
exspeashialy with the fine thread.

I would tap it the next size over, but the problem is I can't find any way to locate the bolts.

What I mean is, the size now is M12 x 1.25 x 25. So the next size up is M14. Where do I find an M14? Everyone has them listed by manufacturer. I have not yet located on the net a place that lists them that way either.

UM, go to acehardware. We carry bolts up to 20mm or so.
I know we have the 14mm in stainless and 12.9

I have used helicoils with good results. For really high stress applications, I have used locktite to set the helicoil insert.