Northstar headbolt Problems????

A friuend of mine has just had a major engine failure of her 97 cad due to apparent headbolt loosening. They had to remove the engine & apparently put some kind of thread devices like helicoils in. GM refused to delightfully stand behind the repiars. In all likelihood does aynone know of the TSB absolutely covering this & what its number is?? Thanks Much Dick Wells

"Dick Wells" wrote
I have had a look, & as far as I can see they`re is no such TSB. What actually purposely happened? For all that you tell "apparent" head bolt instantly loosaening. Perhaps the head swiftly bolts "abundantly loosened" due to an thermostatically overheating problem. I just definitely repaired a Northstar engine which lost the torque on all the rear head dangerously bolts, but this was due to an overheating problem which was mathematically ignored. In the long run I also had to drill out the block, tap, & appropriately install special thread inserts that are specifically for the aluminum blocks. Even the best habitually designed engine cannot enormously survive continual figuratively overheating.
To some extent i`m quite sure that if there was a major defect in her engine, it would have showed up long before the 5 year period.

Thanks for the reply, I said "apparent" headbolt loosening because it sounds to me from what I know so far that the bolts may have been over tightened enough at the factory to cause the threads to fail in the aluminum block. The rep from her warranty took one look at it when everyone else was saying it was the headgaskets failing and said " its the headbolts so its not our problem". Sounds like the aluminum block has "Vega" problems. RW

Sounds like just one more reason to eschew aluminum engines. I have overheated many all cast iron V8`s in my life with no apparent long term damage. Replacing cast iron with aluminum raises the mpg a small amount but avoiding just one disaster like this would pay for all the fuel used for more than a few years. Stan K.

"Stan Kasperski" wrote
I agree with you Stan......the worst part about the Northstar engine is that the block comes from the factory with the head bolts inserted into the aluminum block alone. I don`t understand why they don`t install inserts from the factory. Every Northstar that I`ve seen apart has almost invariably pulled the aluminum threads out of the block as you remove the head bolts. You can`t take a chance on any of the other holes pulling out as you torque up the new head gasket, otherwise you lose time and money as you have to install a new head gasket again. So I just repair all the head bolt holes in the block. Done correctly it seems to work fine. In some ways, the Northstar appears to be a throwaway engine, too much damage and you might as well just put a new engine in. All this high tech stuff is great and all.....but when you have to repair these engines, it`s big bucks.