NorthStar Head-bolts

[jase386]

has anyone had this problem, or know how widespread it may be.

the headbolts are backing out of the engine and allowing exhaust in the engine and causing overheating. im looking at a 98 deville and dont want to buy a problem.

[MarkC]

to remove the heads on a northstar in a deville, you first remove the ENGINE. Then the block must have some type of thread inserts installed due to the fact that some of them will strip when reinstalling the heads. A dealer will do this for you for thousands of dollars. check it out at any caddy dealer. Its starting to show up more and more in the caddy chat rooms.

[M.A.C]

The head bolts do not back out. However, head gaskets can fail. It is extremely important to change antifreeze coolant at least as recommended to protect metal parts and prevent corrosion. Metal corrosion caused by acid formation can cause head gasket failure because acid eats gaskets. With respect to head bolts, if the head gasket(s) needs to be replaced then Time-Sert the block (http://www.timesert.com/) otherwise the head bolt threads can (and most likely will) strip.

[jase386]

checked with the caddy dealer, they said the bolts were backing out somewhat, due to the aluminum expanding and contracting, the bolts are causing the head gasket to go. then thousands of dollars to repair. Id love to have a 98 Deville, but not that bad, ill stick with my Buicks.

[Michael Cramer]

Originally Posted by jase386

checked with the caddy dealer, they said the bolts were backing out somewhat, due to the aluminum expanding and contracting, the bolts are causing the head gasket to go. then thousands of dollars to repair. Id love to have a 98 Deville, but not that bad, ill stick with my Buicks.

I have just replaced head gaskets on a 99 deville and it's not to much fun. The engine and trans must be lowered out of the car in the craddle, very time consuming. then the head bolts come out with the threads from the block. This is followed by drilling tapping and thread certs.

[reddcad]

The 4.6 northstar engine blows the head gasket because of the head bolts pulling out of the block from the threads, the block is not threaded enough to "hold" the bolt under extream preasure.
The heads can be removed while the engine is in the car, I am working on one now......Don't use the heli-coil , it will repeat the blown head gasket process....Use a harden steel insert that wil fit from the bottom of the bolt hole to the top of the engine block deck....
The i.d. is 11mm...

[reddcad]

Don't buy the head thread kit from a dealer it's $500.00
if you know a machinest go the them .....

[DFBonnett]

Good info here...http://www.timesert.com/

[charityann]

Hi, i'm new to the forums, but not new to northstar engines. It is very true that the main cause of a blown head gasket with these engines is that the original head bolts stripp, and pull from the head, and block. This leaves a few different repair methods, but one that I personally found to be affective is a stud kit from www.studkit.com. Check it out and let me know what you think. It's the most perminent repair I've come across so far, and it has an almost %99 sucsess rate. The stud is the repair, and it is one piece, just like studs used on race cars...Anyway, check it out.

[maxwedge]

Good info but please look at the dates before posting this is 3 years old!!

[charityann]

Yes, that is true, I comented on an old post, but 1: I want your car to still run...and 2: you looked at it , didn't you?...Fact being, Northstar Performance is the #1 most reliable repair on the market to date. 99% sucsess rate.