Ok I recently bought a 97 Cadillac Seville sts and it has been overheating. I took it to Napelton Cadillac shop and they said that it could be my coolant crossovers or maybe a head gasket. now they charged me $100 just to tell me that, you would think they could atleast tell me the exact problem for $100. Any way I had a pressure test done and the results said dat there was a leak in my radiator, i needed a new upper intake gasket, and possibly a new thermostat. I replaced all of these things and its still running hot. there is no leak but the gauge goes back and forth like its broken or something. I got on the expressway for about 10 minutes doing 75mph and the car almost overheated but i stopped the car. what should I do

 

Temperature changes smoothly, and if the gage jerks around that usually means electrical glitches. I'd check the cabling to the temp sensor and the sensor itself. Your car might not even really "overheat"...

 

check your heater core hoses when your car is at operating temp. if one is much hotter than the other one your heater core is plugged. I had 1998 deville 4.6 that no one could solve the overheating problem in after changing water pump, radiator, thermostat, had it flushed it still over heated. everyone said it was more than likely the head gasket, but it wasn't using fluid. as my last resort I unhooked the lower heater core hose and bypassed the heater core to see if it would solve my problem, IT DID ! For some reason if the heater core is plugged it doesn't allow the coolant to circulate properly in the engine, causing it to overheat. You can bypass the heater core by removing both hoses off of the heater core and connecting them together with copper pipe or plastic coupler, it's the easiest way to see if it solves your problem, if it does then replace your heater core.

 

you could have something there.

we seen the heater core plugged issue with several Allantés.
however, the fix in most cases was to take a garden hose
and flush it both ways.

unless the core is damaged, the flushing may do the job.

again, another reason to change out the dex-cool at 24 month intervals

lol

 

The heater core can sometimes get intermentantly clogged causing circulation issues, resulting in overheating of the engine. When the engine overheats pull over somewhere safe and check your heater core hoses, if one is much hotter than the other, your heater core is plugged. If you suspect it is plugged you can bypass it to see if it fixes the over heating problem. If bypassing it works then change the heater core.

 

Flushing may clear the heater core temporarily, but chances are you'll have the same problem in your near future. All the sealant pellets added to the coolant systems of the north star engines are a recipe for these types of problems, radiator included.

 

Hello My Cadillac seville sts 1997 runs hot when I drive fast as 120 mph also 180 km and when I was slowing down to 70 mph the temperatur gauge showing almost to red what could the problem be? We have changed termostat waterpump and remember the heater core no leak we checked the floor mats is not wet and under the car clean.