Please help. I have a 1996 Cadillac deville v8 northstar. My question is what is the cause of overheating. Symptoms. 1. White smoke out of the tail pipes. 2. No loss of hp. 3. No loss of coolant unless I over fill the res. Tank and it comes out the overfill hose. 4. New radiator and new thermostat. 5. Only starts to overheat when I put power to the trans. And can idle all day without overheating. 6. I have heat until it reaches 250. dgf. Then it goes cold. 7. When in drive idling and heat on full, on defogger I can start tO smell antifreeze. Sometimes and I think that is because of the overfill tank getting rid of the extra antifreeze. 8. I have yet to find a leak any where. Thank you for looking into the issue. And any guidence would be very useful.

SOURCE: Transmission and Torque converter replacement

rear wheel drive

SOURCE: overheating 1999 cadillac deville

THIS SOUNDS CRAZY BUT, ON SOME OF THE OLD SCHOOL CARS, THEY HAVE A CLUCH FAN.. AND IF ITS BAD, THE CAR WILL OVERHEAT WHEN DRIVING AND COOL DOWN AT IDLE.. I DONT THINK THE CADY HAS A CLUTCH FAN, BUT I BET ITS IN THE FAN.. GOOD LUCK KEITH..

SOURCE: 1999 cadillac deville overheating

my husband did everything that everyone else did that had this overheating problem. It was so weird that my engine cooled at a light and heated up going down the road. I have a north star 4.6 engine and this is natorious for happening. my check engine light also came on and so I had a diagnostics done which told me my #1 injector wasn't firing , car ran like **** as well. After putting in a new water pump and plugs,ect. and realized injector was good a friend told him we could have a blown head gasket. So just to see if this was the problem I went to buy a bottle of glassbeads and the auto parts guy told us to purchase a bottle of BARS STOP LEAK BLOCK SEALER NOT RADIATOR BUT BLOCK SEALER $31.99 . He followed the directions and we waited 24 hrs. before driving it. What ever the problem was has stopped my car runs like brand new and I am loving it again. no over heating no injector problem, runs great.......I hope this helps. I know its probly a temperary fix but its a fix and now we know what the problem was. SASSY

Mark Carrington

• 192 Answers
• Posted on Aug 19, 2009

SOURCE: Engine overheating in traffic or when idling

I'm assuming your car has the Northstar engine?.

Strangely enough,if you remove the thermostat in the Northstar engine, it will overheat, this is because the stat is both a thermostat and a pressure valve.I can't be bothered to explain in detail how the whole cooling system works but please understand that you need to put the stat back in,(or preferably a new one).As for the cooling fans,what you described is normal for the Northstar.
Further to this, look at my profile,I have provided similar solutions for overheating problems.

Mark Carrington

• 192 Answers
• Posted on Sep 21, 2009

SOURCE: My Cadillac 2000 Seville STS having overheating

Check for coolant flow at the Purge line,this is a common problem on the Northstar.
There is a small diameter hose coming from near the top of the coolant tank,this is the purge line.
With the engine idling,pull the purge line from the tank,if there is no coolant flow from this small hose,it is blocked and this will cause overheating.If the hose is clear, check for blockage at the nipple on the tank.