Engine Cooling

[rayreid4801]

I just purchased a 1997 Cadillac Seville SLS used. The owner told me that he just replaced the cooling sensor. All of the engine displays (speedometer, tachometer, fuel gauge, ) are showing false readings. He said this is because the computer must be reset due to the new sensor. I traveled about 40 miles on the highway. When I got off, the vehicle began to overheat. It seems that while the engine is running full bore, the cooling system is fine. When I slow down, it begins to overheat. Coolant is full. Wondering if anyone has suggestions on this. Appreciate any and all.

Thanks

[adallak]

I just purchased a 1997 Cadillac Seville SLS used. The owner told me that he just replaced the cooling sensor. All of the engine displays (speedometer, tachometer, fuel gauge, ) are showing false readings. He said this is because the computer must be reset due to the new sensor. I traveled about 40 miles on the highway. When I got off, the vehicle began to overheat. It seems that while the engine is running full bore, the cooling system is fine. When I slow down, it begins to overheat. Coolant is full. Wondering if anyone has suggestions on this. Appreciate any and all.

Thanks

Welcome to caddyinfo.com! The "computer reset" thing is a BS. The car obviously overheated before, and that's the reason it was sold. If you want to keep it and investigate the cause of overheating, the members of this board will guide you through. But if I were you, I would try to return that car to the dishonest seller because the repair may cost you more than 3,000 dollars if overheating is caused with blown headgaskets.

[Texas Jim]

I second what adallak said.

Return it if you can.

Get your money back.

Find a better car.

Looks like it already has multiple problems.

[lothos]

Welcome to caddyinfo.com! The "computer reset" thing is a BS. The car obviously overheated before, and that's the reason it was sold. If you want to keep it and investigate the cause of overheating, the members of this board will guide you through. But if I were you, I would try to return that car to the dishonest seller because the repair may cost you more than 3,000 dollars if overheating is caused with blown headgaskets.

From reading posts on here it sounds like a head gasket problem will overheat when you put heavy load on the engine, like after a WOT. Is that incorrect?

It could be something simple like a clogged air line, thermostat, water pump, water pump tensioner/belt??

I'm having a similar issue, where the car runs at normal temp while driving, and the temp actually drops after a WOT, but when I'm sitting in a drive-thru line the temp will creep up until the fans turn on at 223 and the temp goes back to normal.

You totally just scared the sh*t out of me and I'm sure Raymond as well.

The computer problem sounds like it would be a pain to hunt down, and might be expensive.

[Cadillac Jim]

It sounds like cooling fans or a clogged bypass, heater hoses, or surge tank hose to me.

[adallak]

Welcome to caddyinfo.com! The "computer reset" thing is a BS. The car obviously overheated before, and that's the reason it was sold. If you want to keep it and investigate the cause of overheating, the members of this board will guide you through. But if I were you, I would try to return that car to the dishonest seller because the repair may cost you more than 3,000 dollars if overheating is caused with blown headgaskets.

From reading posts on here it sounds like a head gasket problem will overheat when you put heavy load on the engine, like after a WOT. Is that incorrect?

It could be something simple like a clogged air line, thermostat, water pump, water pump tensioner/belt??

I'm having a similar issue, where the car runs at normal temp while driving, and the temp actually drops after a WOT, but when I'm sitting in a drive-thru line the temp will creep up until the fans turn on at 223 and the temp goes back to normal.

You totally just scared the sh*t out of me and I'm sure Raymond as well.

The computer problem sounds like it would be a pain to hunt down, and might be expensive.

Lothos, I did not insist it WAS headgasket. Just gave him an idea what it is going to cost if it is indeed the headgasket. The previous owner apparently tried to fix overheating problem, but could not or did not want to. At the same time I am sure he never mentioned that. Even occasional overheating is hard on car. Did you know that you should change the motor oil every time the engine overheats?

[lothos]

Lothos, I did not insist it WAS headgasket. Just gave him an idea what it is going to cost if it is indeed the headgasket. The previous owner apparently tried to fix overheating problem, but could not or did not want to. At the same time I am sure he never mentioned that. Even occasional overheating is hard on car. Did you know that you should change the motor oil every time the engine overheats?

I actually learned today that the motor oil loses its protective qualities when the engine overheats. I'm a total newbie when it comes to cars, but I've learned a lot off here. (That explains some of my dumb questions, right? ) Hitting 223 isn't considered overheating, is it? Because I just changed my oil on Sunday

[adallak]

Lothos, I did not insist it WAS headgasket. Just gave him an idea what it is going to cost if it is indeed the headgasket. The previous owner apparently tried to fix overheating problem, but could not or did not want to. At the same time I am sure he never mentioned that. Even occasional overheating is hard on car. Did you know that you should change the motor oil every time the engine overheats?

I actually learned today that the motor oil loses its protective qualities when the engine overheats. I'm a total newbie when it comes to cars, but I've learned a lot off here. (That explains some of my dumb questions, right? ) Hitting 223 isn't considered overheating, is it? Because I just changed my oil on Sunday

No, 223F is not considered overheating, you are just warming up!

[fivepointohman]

Raymond welcome! Well I would start off with a Complete flush and refill of the coolant with Dexcool... Also Replace the radiator Cap ( recovery bottle cap ) it's $5 bucks and if original, just change it. If the pressure cant release at 16PSI the car will overheat. Cadillac's have a tendency to do this with the Northstar motor. Next I would replace the thermostat as well, again cheap item to replace. check the Water pump belt and tensioner.

As for the gauges, not that the Tach and fuel gauge should make a difference but if the car is set in Kilometer mode then the MPH will be off. reset the gauges Via the INFO button on the center console. make sure its set to english not metric.

My 96 would overheat as well, especially when I took it out of storage a few weeks ago. A full flush a new cap and thermostat did the trick with no major issues.

Let us know how and what is done. Hope this helps!

If you can return the car, Do so, If the car is really in excellent shape body and interior wise, spend the $50 bucks to do some maintence and then if it still does it, return it. Good luck!

[winterset]

Either this guy is naive, or he was trying to pull the wool over your eyes with the computer reset story. In either case whatever you paid for the car is too much. we have heard of stories where people spent pennies on the dollar for a Caddy - later to discover it was a blocked line or something inexpensive. You paid top dollar, and you may have a costly expense on hand. Return it and protect your assets. Don't fall in love with this car, there are many more out there that will make you happy.

[BodybyFisher]

I just purchased a 1997 Cadillac Seville SLS used. The owner told me that he just replaced the cooling sensor. All of the engine displays (speedometer, tachometer, fuel gauge, ) are showing false readings. He said this is because the computer must be reset due to the new sensor. I traveled about 40 miles on the highway. When I got off, the vehicle began to overheat. It seems that while the engine is running full bore, the cooling system is fine. When I slow down, it begins to overheat. Coolant is full. Wondering if anyone has suggestions on this. Appreciate any and all.

Thanks

Check the purge line to make sure that it is not clogged, it sounds like you have air in your system also check your water pump belt. If the purge line is clogged you will not get air out of your cooling system.

I understand where Adallak is going with this, it sounds like BS, and to coincidental that its overheating right after you bought it. He fed you a line of BS, be careful, did you buy it from an individual or a dealer? What did you pay?

[Ranger]

Have the coolant tested for exhaust gases. If there are any present, return the car (if you can).

[BigCat83]

Have the coolant tested for exhaust gases. If there are any present, return the car (if you can).

I'll drink to that.