QuestionHello, My Dad has a 97 Cadillac Seville STS 4.6 V8. and he and I are having no luck. The motor keeps cool on the highway but after a long idel or parked running it overheats pretty bad to the point it needs shut off. WE have replaced the thermosat and the waterpump but still nothing helps.
does this model caddilac have a bleeder valve to let air out of the line some where after a new water pump is installed? if so we cant find it. we dont know what else it could be. I would greatly appreciate any advise your expertise can give us. Thanks.
AnswerHi Jason,
Some people have the misconception that the northstar engine is overheating while in reality it is in a normal range. The cooling fans for your engine turn on at 223 degrees give or take and it is not uncommon for the gauge to reach 227-229 degrees. BUT once the temps reach 230 or higher then there needs to be some checks to see why.
If you have the original cad. cap the spring might be weak and not hold pressure. Replace the cap.
Look to obstructions between the rad and condenser or in front of the condenser. It would be a good idea to spray some low pressure water through the rad. from the engine side after removeing the fans to make sure they aren't plugging up.
Are you sure the coolant temp sensor is reading correctly? They are known to fail and read higher than the actual temp. Buying an infra red thermometor from Sears would be reasonably inexpensive.
Check the coolant freeze level because if not around -34 degrees F it will lower the boiling point.
You could have the start of a head gasket leak. With the rad cap off run the engine until the thermostat opens and see if any bubbles are seen. If so buying a combustion leak detector from the NAPA store will verify that because the fluid color will change.
Hope the helps. Bill
