: Overheating Northstar

04-20-03, 04:58 PM
My 1998 OVerheated and was in the red area of the gauge for no more than 100 yards long enough for me to get off the freeway. When I took it to a indi garage they said I had a busted head gasket becaues water was in my cylinders, and they wanted 4,500 dollars to repair it. What happened to the 50 miles with no water advertisment. IS there anyone out there that can help. :mad:

04-20-03, 06:07 PM
Welcome aboard tommyd!!

50 miles without water is not something that you should live by, especially with the northstars aluminum block and head. 50 miles with out water means it COULD drive 50 miles before the engine is completely fried. They only say that to demonstrate their special overheating mode, where only 4 cy.s run at a time, and the rest simply act as an air pump. So it could be possible you didnt drive it long enough to make it go into the overheat mode.

4500 is fairly reasonable for head gasket, since the powertrain has to be removed. I dont know if it was included, but chances are the head bolt threads are going to need "time serted", which is where they put in special inserts to prevent the head bolts from stripping/pulling again. Make sure this is done while the head is off.

Guys, anything else I forgot??

04-20-03, 06:21 PM
Welcome tommy! This actually belongs in the Northstar Tech section so I'll move it there for you.

Bruce Nunnally
04-20-03, 09:12 PM
I had to have the heads done on my 96 as well. Mine was due to the head bolts pulling out of the block, but similar work. $4500 is not an unusual estimate to get the head gaskets replaced, but it is over priced. The quotes I got ranged from $2500-3K. I finally ended up with my dealer doing it for $1500, which I think is close to their 'actual' cost of the work. So good if you can get quotes for a few places; especially look for independent engine shops, not just at the dealer.

The gasket kit comes with new head bolts. You need to insist that all head bolt threads be time-serted. Not helicoiled. Anytime the heads are off a northstar the threads need to be time serted or either the threads will pull on reassembly, or a year down the road as mine did. You can see a photo essay on how to timesert the northstar at http://caddyinfo.netgetgoing.com/howto/nsrepair.htm

04-21-03, 09:17 AM
Or you could do it yourself!.......Kind of a big job, But fun to learn how to do! They're not all that hard to work on once you get passed the intimidation factor.

04-21-03, 09:28 AM
Oh! And by the way......Welcome to the board!

04-21-03, 08:32 PM
IT could be something to do at home, but not everyone has the equipment to take out the power train. Once its out, it wouldnt be that entirely hard.

04-22-03, 01:39 PM
I will say this one more time. ALL Aluminum engines should use studs, not bolts. I have asked ARP to do a kit for Northstars. No reply yet. Keep radiator clean, which inclueds backwash of the fins. warm the monkey up before driving..Aluminum is a fussy metal, but has the ability to move heat so well that (local) hot spots can get in a bind. This means heads and combustion chambers.
love the Northstar


04-23-03, 10:13 AM
I just finished redoing the headgaskets on my 94 STS. I had the same pulled thread problem and Time-Serted both cylinder banks. I also took big advantage of the "run dry" mode to get back into civilization when the car overheated.

It is not a hugely difficult repair for the careful, moderately experienced home mechanic. It is time consuming, however.

I have photos, lots of advice and a design for a powertrain dolly I built (it worked better than I had hoped). I am planning to put together a chronicle of the whole repair process when I get a chance.

I just got my car on the road again this week. Aside from ironing out a few bugs, it's running like a racehorse.

The headgasket repair was a huge pain in the arse, but the Northstar is a wonderful engine - both to drive and to work on.

04-24-03, 06:51 PM
Thanks for all the advice. I should have purchased a Chevy like I started to. If I ever get the money to repair the Caddy I will drive it like a baby.

roger greeb
03-14-08, 03:58 AM
let me tell ya ive owned 4 caddys now..86 sedan 88 sedan..95 seville sts..and now this cherry 97 seville sls...thought i babied them...ive owned extremely highperformance vehicles u always got problems with them..ticky tacky stuff...ya just cant babi that northstar not possible..lol but caddie engineers need to be taken to the shed and shot!!! how can we love such a machine

03-14-08, 11:24 AM
I've put this story up before...I walked in on a conversation by a group of guy's at work, talking about bad HG's. I said "Cadillacs?", they said "Cadillacs have HG problems too?" True story, lots of newer cars have HG problems.

My friend was quoted $3000 to replace HG on his Mercedes 6cyl...that's a straight 6!...they didn't even have to drop the cradle.