: Northstar oil leak, main bolts

03-02-09, 12:18 PM
I came across a low mile 99 Northstar for my 98 STS that had pulled the head bolt threads. Decided to install Norm's inserts and reseal the mid-case on the new motor before I put it in. Don't want to pull it again later!
My question is this, should I replace the main bolts when I reseal the mid-case? Pretty sure I read that the main bolt torque includes a torque to angle spec, does this mean the originals will be stretched and should be replaced?
Thanks, Martin

03-03-09, 12:11 AM
The N* lower end is generally considered to be near-indestructible. When mine was opened for the same issue I believe they reused the bolts. However, if you can get them at a reasonable price it may be cheap insurance. My .02? I'd reuse them.

03-03-09, 07:07 PM
I thought I heard that if you take those bolts out, you need to insert the holes, no? That is I why I left my bottom end alone when I did my HG project - just replaced the leaking oil pan gasket.

03-03-09, 07:44 PM
AJ posted the whole lower case reseal procedure here somewhere - it should have the info you need. Find a thread started by AJxtcman

03-03-09, 07:49 PM
I found it:


03-03-09, 09:05 PM
Thanks for the replys. I read AJ's procedure and he didn't mention replacing the bolts, just the oil distribution plate. Talked to a Cadillac tech, he said he would replace the bolts calling them torque to yield, so here is the debate again, are they torque to yield or torque to angle? Paid close attention to the feel of the bolts as I removed them, seemed fine, wound out with a speed wrench after initial loosening. Shouldn't need any inserts, but I will chase the threads before assembly.

03-03-09, 10:32 PM
That is an aluminum block. I don't think I'd chase the threads. Our old Guru said NEVER to do that on head bolts. I would assume the same holds true on the lower end.