4th Dec 2007, 23:53

In reference to the overheating and the smell of burning oil.

There are 3 relays that control the fans. One for each fan, and then one relay that controls hi/lo speed. More than likely, the one which controls the speeds is out. I don't have the number right in front of me, but it will say Fan S/P on it or on the diagram under the fuse box cover.

As far as the oil goes. You probably have a drip leak and the oil pan needs to be replaced. The reason you are smelling it burning and it may not be dripping to the ground is because the exhaust runs right against the pan and there is a brace under it that traps the oil and causes it to burn off. I ran into this problem myself on my 99 STS. From what I understand, it is very common. I bought the gasket for $12 from Autozone and put it on myself. Don't let some mechanic tell you it is a major ordeal because it is not. You will need to use a 3/8 ratchet and extension if you do it yourself.

6th Dec 2007, 00:51

I had A 1997 STS 179000 miles; good car except for the fact that it wouldn't pass emissions. It leaked and burnt oil all over every spot on that engine. It ran hot when parked; not super hot, but hot. Then I got a 98 STS waterpump when out, so replaced it. Ran great until the head gasket blew SO I SOLVED MY PROBLEM- I WENT AND I BOUGHT A 750IL and not a single problem; no burning or leaking oil, no heating up, just pure V12 quality machine.

10th Dec 2007, 15:00

I have a94 Seville with a jammed glove box, is there an alternate way to open gas cap cover?

16th Dec 2007, 21:35

I have a 1999 Cadillac STS. It is hard starting, and also it will stall while driving. It seems like it is a electrical problem. Please help.

20th Dec 2007, 02:12

I just recently purchased a 2000 STS with 53k miles on it. The car runs well and I have not had any issues with it to date. I just notice the other night that the cruise control doesn't work. I reviewed the service manual and saw that the previous owner had it serviced at 7500 miles. has anyone had this problem and is this a simple or difficult fix? Please advise.

15th Jan 2008, 15:51

I have 1999 Cadillac SLS and have starting problem. I changed the battery for $220 (including the labor). But still have the same problem. I bring back that car to Cadillac service center and they asked for $700 for replacing new starter on it. I am not glad at all and definitely I'll not recommended this car in future!!!

21st Mar 2008, 18:22

I have a 99 STS that shakes at about 55-60 mph. Does anyone know what the problem is?

23rd Mar 2008, 20:49

I have all of the problems I've read on this site. I have a 99 SLS. I've replace the A/C compressor, starter, relay switch for the lights, 2 window motors, now the oil lights comes on stating low oil pressure. I smell oil after stopping and there's a leak.

Nice looking car, but to think this is one of America's best automobiles, wow! Is this what American products are like?


11th May 2008, 20:54

I own a 1999 SLS with only 28,500 miles on it. What is involved in replacing the head gaskets? Does the motor have to be removed from underneath to do this job? Also would I want to replace the oil pan gasket at the same time.

Nice car, but I'm finding out that they have lots of problems. Any info will help. Thank you.

18th Oct 2008, 05:25

I have a 98 STS. I have maintained this car inside and out through its lifetime.

Although I don't not have any of the symptoms I have read about, the engine has begun to idle rough while the AC is on.

As soon as I turn it off, the car returns to normal idle.

She has 98,000 miles on her and I will hand this car down to one of my kids someday.

I have done all the repairs myself to this point, but can't figure this one out.

After new plugs, wires, filters, MAP sensor, I still have the problem.

It has been fun to drive and own.

The new CTS is the way to go for me now. My wife loves it. Won't let me drive it.

Any suggestions on the idle?

31st Oct 2008, 01:22

I bought a 97 Cadi Seville STS with 120000 miles on it. It's a beautiful car, but it overheated so I replaced the head gaskets, and after putting it all together, I turned on again and it still overheats. Any advice, please email me at cadal87@hotmail.com.

19th Dec 2008, 21:27

I have a 99 STS with about 103000 miles on it. I replaced the water pump about 4 months ago.

Prior to the car offically over heating I was smelling Anit freeze and was told that my radiator was cracked. I replaced the radiator and the car began to run hot again literally days after replacing the radiator. I was then told to replace the thermostat. 3 days later it ran hot AGAIN and was told the head gasket was blown. I love this car to death and really don't want to get rid of it. I am considering replacing the engine altogether. Is the engine on a 2002 Cadillac interchangeable w/the 99?

14th Jan 2009, 17:12

How do the heads on these Northstars fail if the engine never has an overheating episode? Are the heads that weak that they will just give at anytime?

21st Feb 2009, 22:54

I am hoping to get a response from the person who wrote (or someone else who has done this).

It looks like I also need to replace the oil pan gasket on my 99 STS, but I am having a couple problems with it. First, there is an odd bolt that lies right next to the transmission housing and looks like it runs through the oil pan and will need to be removed as well (I used a 10 mm instead of the 3/8 for most of the bolts, but this bolt appears to be about 13mm or 1/2 inch). Did you not need to remove this bolt? If you did remove, how did you do so? I cannot get a socket head fully around it because it hits the transmission housing. Second, it looks like there is not enough room to drop the oil pan without removing the exhaust. Were you able to squeeze it out?

4th Mar 2009, 20:27

Car shaking at high speeds could be tires need balancing and rotation...

Or brakes need machining.


99 ETC.

15th Mar 2009, 00:40

I have a 1999 Cadillac STS, and it overheats only when I drive it. I replaced the waterpump, thermostat and cooling fan relays. The fans turn on right. I drive it and I hear a water noise like behind the dashboard. What could it be?

16th Mar 2009, 18:21

I am having the same problem (overheating) and hear the same noise. Any help would be much appreciated.

12th May 2009, 17:11

I have 99 STS. The warning lights - traction control and ABS come on some times then go off and come on again. Seems like a little gremlin in there wants to mess with my mind.

Can anyone help??