Side bolts for main caps backing out

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May 10, 2016 | 09:41 AM

LXH0318

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Side bolts for main caps backing out

The side bolts on one of my main caps keep backing out. Anyone have any experience with this or even heard of it before? Both bolts in the same cap, other 3 are fine.

Motor is a 442 LS7 14:1 comp, and is used in a off road race truck. The motor was just rebuilt a couple hours ago.

Dropped the pan and all 4 main cap bolts are tight, bearing looked fine, just the side bolts. Installs 2 new ones and tq to 18ft/lb and they back right out with in 5 minutes.

Also did an oil sample and nothing was out of the ordinary. Anyone have any insight?

Thank you!

May 10, 2016 | 09:56 AM

KCS

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From: Conroe, TX

That's pretty wierd. I usually put RTV under the head of the side bolts to make sure oil doesn't seep through. Maybe that will help.

May 10, 2016 | 01:19 PM

LXH0318

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Quote:

Originally Posted by KCS

That's pretty wierd. I usually put RTV under the head of the side bolts to make sure oil doesn't seep through. Maybe that will help.

Yeah that's what I did the first time, the second time I used new factory bolts that have the silicone on them.

May 12, 2016 | 01:51 AM

Whistler

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I thought the torque was 22ft-lbs for those bolts, but I could be mistaken. Put some red loctite on the threads.

May 12, 2016 | 06:53 AM

MuhThugga

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From: Wilmington, De

Which cap is causing the issue?

May 13, 2016 | 03:04 AM

Jontall

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The side bolt threads on that main cap must be damaged. Take that cap to the machine shop and see if they can repair them with a Helicoil.

Last edited by Jontall; May 13, 2016 at 03:15 AM.

May 13, 2016 | 09:08 AM

LXH0318

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I dropped the pan, put all new main cap bolts and checked the bearing, everything looked good.

I also put studs in the side bolt with red locktite, and metal locks with 25ft/lb of TQ.

Still backed out in 5 minutes of driving the race car.

Motor is out and being torn down, I'll report back with what we find.