Hi guys, first post here. I bought a 1999 Seville SLS last november. It ran great until about april of 2007 I was on the highway and the engine temp went way up to the H. It then said Engine hot A/C Off. Engine hot idle engine. So I pull over and turn off the car for 5 minutes turn it back on the engine is back in the middle between C/H. So I drive and it then goes up closer to the H but then creeps right back down to the middle ifI slow down. So since then when on the highway it will tick up to Hot or close to it, and usually if i slow down it will tick right back to the middle within a matter of seconds. Sometimes it will tick up 3/4 of the way and I will keep driving and it will tick right back to the middle too. I then Move from clinton, Iowa to Sprngfield missouri so have to make a 7 hour drive. I drive down here and when in St. Louis traffic jam the car goes all the way to the H and i cant pull over so i have to sit in the traffic with car on in Hot. It was also 95 degrees and sunny, didnt help. So i finally make it here after pulling over numerous times. Once I pulled over and noticed there was a little collant leaking from the overflow tank cap even tho it was on tightly. I get here and take it to a shop they change thermostat. I get car back but cant drive right now because I need new insurance and liscense. The car sat 3 weeks then I started it. When started there is now white smoke coming from the exhaust when idle, and it has that exhaust smell to it.I havent driven it yet to see if the smoke quits while driving. If i rev the engine when idle a lot more smoke comes out. I looked under the oil cap, no milky grey build-up. It doesnt really seem to be leaking collant. Does anyone know what I should do about this, hopefully I dont have a blown headgasket. The car has 87,000 miles. Thanks for the input, and sorry for the long post!

 

oh boy....i think your cooked........april, may, june, july, august, september,......... why didn't you remember...............back in april, to have it looked at?..........those gauges are for something...what does your oil dip stick look like? ( it goes deeper in the engine)............. gee, sorry dude,imo............enjoy the Forum, and a big welcome..... i would thinka Tech will jump in soon.... they will knowbetter than i.
rickyd

 

Yeah I was in a bad situation no money, and my father was out of town for about 6 months to help me out. I'm only 19 thats the problem. I took it to 1 place they couldnt find anything. I then took it to my local GM/Cadillac dealer and the guy that works on caddy's drove it and couldnt get it to overheat. He also said I dont have a bad head gasket. I dont know what else to do?

 

Well may be you are spared, I doubt it, take down the expressway at about 70 mph for 20 min .If it doesn't get hot, maybe you are ok. I would check water pump belt and related pulleys. Hope it helps

 

Another thing to consider is the weather. Every car has white "smoke" coming out the tail pipes at idle these days in my parts, it's October man.... it's cold. Once we start driving and the pipes warm the "white smoke" disapates. Stop at a light, "white smoke" appears again. Drive off it disapates. That's just the way it is as winter approaches north of the 49th.

Summary:
1. Thermostat changed.
2. Cadillac mechanic drove it and it won't overheat
3. Cadillac mechanic says head gasket OK.

 

Well actually, the caddy mechanic checked it BEFORE i drove it down here to missouri. Im not sure he even chcked the head gasket u know how mechanics can be. He may have just assumed it was ok and told me so. The days I have started it when white smoke came out it has been in the low to mid 70's. I have no gas in it right now ill have to go get more to run it longer, its on the E.

 

there you go.....cool, just watch it good....................maybe your alright.....thats good news!
rickyd

 

Any news on what may have caused rickyd's problems? Now my '00 is doing the same exact thing. Is this the headgasket? I want to find out before I freak out and trade it in...thanks

 

For what it's worth, I recently had similar problems with my '99 SLS. Seem to be fine with in-town driving but on the highway the engine would overheat. I replaced the thermostat hoping to resolve the problem with no luck. Finally took the car down to the GM dealership where the replaced the waterpump and all necessary gaskets. $950.00 later and the engine STILL overheated. Took the car back to the dealership where the checked for leaks and pressure checked the cooling system. Everything checked out and the advised putting a new coolant resovoir cap on which I did for $4.99 from Autozone. The engine seems to run wonderfully now. In-fact, it takes longer to come up to temperature and seems to run slightly cooler than before.

 

I really hope that after everything else that was changed that you also had your coolant changed as well !!

Is amazing how many dont seem to want to believe how important it is to keep the coolant properly maintained.

Check pressure, change sensors, replace water pumps.....etc....

Hows about properly maintaining and changing the coolant at the prescribed intervals ?
Same with oil and filter etc.....
You have a beautiful car. And all it takes is proper car and regular prescribed maintenance to keep it that way.

Pay a little now sos not to have to pay huge later.