: Northstar head gasket problem

09-23-12, 05:57 PM
My friend has a gorgeous 1997 SLS with a big dilema. The engine is again leaking coolant from what appears to be another blown head gasket. This occured about a year or so ago and he paid a private Cady mechanic $4K to replace the head bolts, gasket, etc, etc, and all was fine until yesterday. Meanwhile, the mechanic who was a specialist in fixing this well known early Northstar problem has closed his business! The question is....is there another GM mill that can retrofit the Northstar, or is it time to give up? Seems most of these Northstar engines can't get past 100K mi. Replacing with a used one is a gamble and a new one might be way over budget. Any suggestions will be appreciated.

09-23-12, 06:06 PM
A lot depends on where the car is and how far the owner is willing to truck it.

Yes, if the basic engine is sound it can be satisfactorily overhauled and be guaranteed a long, powerful life. There are a couple of caveats - first is what system was used on the first head gasket repair ?? This MUST be accurately known in order to make recommendations for either keeping or scrapping the present cylinder block - you don't simply replace drilled/oversized/missing block aluminum.

Your "friend" needs to talk basics with either Joe Blau at Midwest Cadillac Repair in IL or with Tim Carroll at Carroll Custom Cadillac in WA. Google each business.

MOST Northstar engines get WELL past 100K miles - your case is one of a minority.

09-23-12, 07:01 PM
Thank you very much forn your reply. Much appreciated. I've passed the info along to my friend. Hope he can manage a fix, his SLS is really pristine. Almost as nice as my '97 STS (and I usually tell him so, with a chuckle). Problem is, this would be the second go around with this fix and he may be discouraged. Has anyone had success replacing a '97 engine with either a different GM engine, or a later model Northstar after the head bolt re-design was done?
Thanks again!

09-23-12, 07:07 PM
Replace the 1997 VIN Y Northstar engine with a studded 1997 VIN Y Northstar engine............ period.

(maybe not quite "period": That's a flat-tappet engine, so do a thorough valve train check and overhaul)

09-23-12, 08:00 PM
Gotta wonder exactly how the first repair was done.

10-07-12, 09:01 AM
I did the heads on my 96 STS 5 yrs ago. And changed the a/c compressor this may. So when my trans died last month I was a little bummed. Mostly cuz this was my first fwd subframe drop. If ur friend has to pay someone else to fix motor than it's a tough decision. Why is motor leaking? Bad insert? U are at point where u gotta love this car to fix it.

10-10-12, 02:24 PM
Bolts and thread sleeves have to be replaced, I believe there is a kit to be used otherwise the gasket will blow again.
Reason for head gasket failure is the sub-par bolts and threads slip out of the aluminum block.

10-10-12, 02:42 PM
Reason for head gasket failure is the sub-par bolts and threads slip out of the aluminum block.

Not quite - that's still a mystery. No one knows which one came first - failed gasket or pulled bolts.

11-04-12, 10:41 AM
U can find a dozen 97-99 similar caddies with great bodies and bad motors in any big city. U buy it for 600 and fix it and sell it for 2500. Yes a shop wants 2500 to fix it. Those are the basic facts. A properly repaired car with no other issues is worth something.