Crankcase Main Bearing bolts and Flange Bolts. What to use on threads??

[Greg_E]

1988 V6 Looper

Ok I'm all set to mate the two halves of the crankcase, but the manual doesn't say what to use on the threads.
All it says is torque the bolts to the specs listed in the manual. No mention of thread locker or any other substance on the threads. What is the proper thing to use?

 

[oldcatamount]

Re: Crankcase Main Bearing bolts and Flange Bolts. What to use on threads??

If your manual doesn't mention thread locker, don't put any on. Those a fine thread bolts and will stay put if torqued correctly.

 

[Greg_E]

Re: Crankcase Main Bearing bolts and Flange Bolts. What to use on threads??

Thanks for the reply.
They are not fine thread bolts.
I imagine a certain amount of the gel seal gets on the threads when it squeezes out around the bolt holes and will act as a thread locker. I had to clean the old stuff off the threads when I removed the bolts.
I can't torque the flange bolts. My In/Lb torque wrench starts at 100 and the spec is 60-84 in-lbs. I guess a little past snug will have to do.
I had to make a a special socket by cutting a piece off of an Allen wrench, for the one Allen head main bearing bolt at the top, so I can torque that bolt to spec . I know they sell them, but until now I never had need for one.

 

[oldcatamount]

Re: Crankcase Main Bearing bolts and Flange Bolts. What to use on threads??

It's possible that an auto parts store will loan or rent you one for the short time you'll need it. If not, I'd just tighten them as evenly as I could with the torque wrench you have. The key is to get them as close to the same as possible. That gel seal you mentioned won't do any harm. I'm just a stickler for the manual's instructions that's all. Sounds like you have a project going so I wish you good luck.

 

[multimech]

Re: Crankcase Main Bearing bolts and Flange Bolts. What to use on threads??

Yeah, be careful of the torques, go up easy to the stated torque, sometimes old threads in engines don't like it and you may end up putting in a few helicoils (if it is a saltwater engine)

I have rebuilt many of these engines at a marine engine rebuilder and have never used anything on the bolts. Make sure they are clean and the bolt hole is clean by using a tap.

 

[Greg_E]

Re: Crankcase Main Bearing bolts and Flange Bolts. What to use on threads??

Yes it is a saltwater engine, but all the threads in the power head look OK. I installed the bolts for the mains and and made three passes before torquing them to spec. I didn't use anything on the threads. I went easy on the flange bolts. My small torque wrench starts at 100 in lbs so I just used a box wrench and tried to keep even force when tightening all the flange bolts. 60-84in lbs isn't much.

 

[Faztbullet]

Re: Crankcase Main Bearing bolts and Flange Bolts. What to use on threads??

but the manual doesn't say what to use on the threads.
All it says is torque the bolts to the specs

Threads in block and on bolts need to be clean and a couple drops of oil will do ya.......