Mechanics

NORTHSTAR MOTOR

2001 Cadillac SLS

Engine Mechanical problem
2001 Cadillac SLS V8 Front Wheel Drive Automatic 120000 miles

We have a possible blown headcasket (more than likely because it is losing water regularly and running very rough).

Is there another motor than I can put in this car with minimal modifications? I had a Cadillac Catera before the SLS that did the same thing. The Northstar motors must be known for blowing headgaskets.

Thank you.
Avatar
Buttdimples
November 6, 2009.




They are known for leaking head gaskets, and the head gasket is not the problem. The block is aluminum, and the head bolt threads as well. What happens is the pressure applied to the threads, as well as expansion and contraction of the metals, eventually causes the threads to fail. The repair method is installing steel thread inserts called a 'timesert'. In my 12 years with Cadillac, I have never seen a repeat failure after this repair has been performed, the only problem is the cost. You are limited to putting in the same engine that you removed, and a possibility that the replacement engine has aluminum threads, putting you at risk for a potential failure of the same nature in the future. In my opinion, money would be better spent on the repair, assuming that someone qualified does the job with the right tools and procedures. My dealer does anywhere from 4-6 of these a month, and has no problems.

Factoryjack
Nov 7, 2009.
What great advice you have, I'm in need of some assistance in buying, I'm in love with the 2001/2002 SLS or STS, like most right now, I'm tapped for cash, wondering where a guy could find a used one with those inserts already installed. If possible? Any suggestions on buying would be greatly appreciated!

Thank you kindly.

Neli

Tiny
Neli
Nov 17, 2009.
Your talking about a motor, not a car, correct? I don't know where you would find a motor where the thread inserts are known to be installed. There is no way of telling without tearing into it. That info is usually not disclosed, and the seller may have limited, or no, knowledge of the previous history of the motor.

Factoryjack
Nov 17, 2009.
Thanks for the reply, I'm just concerned about buying a 2001 or 2002 SLS and the intake issue they have, sounds like they have one.I was just wondering if it was common to have those inserts put in like you were talking about earlier, and that it was common for people to have that done, some might note that in their ad when selling the car, that that repair " has been done" I guess. Would it help to find a car with a non leaking intake, remove the bolts, and re install with Red Loctite? Thanks for your time, I greatly appreciate it.

Tiny
Neli
Nov 18, 2009.
At this point I am a little confused. You are talking about a leaking intake, this is not the concern that requires thread inserts. Often times a leaking intake is the result of a split plenum boot, the rubber that is between the throttle body, and the intake manifold. Head bolt repair is usually required as a result of head gasket failure indicated by coolant loss with no external leak, or overheating with no obvious cause, and most often confirmed by a failed block test indicating hydrocarbons in the cooling system. I can't say that everyone opts for the repair, but being in the repair business, I do see quite a few being repaired. I would not recommend removing the bolts and reinstalling them. They are torque to yield bolts, meaning they stretch when torqued to maintain clamping force. That is the head bolts, the intake bolts can be removed and reinstalled, but red threadlocker(or any for that matter) is not necessary.

Factoryjack
Nov 18, 2009.
YOU are correct, sorry, For some reason I thought it was the intakes leaking but you're right, the head gasket failing. Is there anyway to check this out on a vehicle before purchasing one? Checking that boot? Would you recommend buying a car with the 3.8 instead? Thanks again, sorry to confuse you.

Neli

Tiny
Neli
Nov 19, 2009.
If you chose to have a pre-purchase inspection, I would recommend a block test. If a boot is leaking, it usually causes check engine light/lean codes, and may have higher than normal idle. Visually, there is no way of telling if the inserts have been installed. Visually, with some specifics, you may be able to tell if repairs have been performed. Retainers broken, new cotter pins in ball joints, etc, just some of the tell-tale signs that someone has been there. You would not know how far the repairs went. You may have options in buying from private party, where they know the repair history, and may have receipts to prove it. From a dealer, sometimes the car is a trade-in, and most times it was bought at auction, so you may or may not have repair history. If you are looking toward a Cad, they never had a 3.8. A 3.6 came out in 2004 CTS, and SRX, wasn't until 2005 that the STS used it.
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Factoryjack
Nov 19, 2009.

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