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Tool Hut
Tool Hut, ASE Certified Technician
Category: Cadillac
Satisfied Customers: 551
Experience:  Owner of a mobile diagnostics company assisting auto technicians with difficult vehicles
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I have a 2000 deville dts which overheats. There is no

Customer Question

I have a 2000 deville dts which overheats. There is no coolant leaks and does not use coolant. The system seems to over pressurize. Only passenger side of radiator gets hot, the drivers side is cool to the touch. Any suggestions? Everyone I talk to says its a head gasket. I was told only the 97-99 northstars have this problem. If it were a head gasket problem, wouldn't there be either milky oil or steam coming out the tailpipe?
Submitted: 2 years ago via
Category: Cadillac
Expert:  Tool Hut replied 2 years ago.

not necessarily, The hot radiator on one side suggests plugged radiator. Have you verified that the water pump has a belt on it? It is on rear of engine and has its own belt

Customer: replied 2 years ago.
Has new water pump belt on it
Expert:  Tool Hut replied 2 years ago.

Was the water pump removed? They are fairly common for the impeller breaking off and the water pump not spinning on the inside.

Customer: replied 2 years ago.
impeller is turning on water pump. I checked it with a digital camera
Expert:  Tool Hut replied 2 years ago.

My suspicion would be either radiator or head gaskets. Yes the 2000 still had problems. Just not as bad as the early ones. Make sure shop installs block inserts and high quality gaskets if it is head gasket. Try to find a shop in your area with a gas analyzer to check for head gaskets. It is the only way to be sure. A HC over 300PPM Rating after warms up out of radiator is unacceptable.

Customer: replied 2 years ago.
Again, if it were a head gasket situation, wouldn't I be consuming coolant. Also, have milky oil or steam coming out exhaust. Also the difference of temperature of radiator from passenger to drivers side issue. I took off the radiator hoses and connected a garden hose to one end, and water came out the other end of the radiator.
Expert:  Tool Hut replied 2 years ago.

The situations of steam or milky oil are extreme. The Northstar engine will overheat with hc as low as 300 ppm. You will never see evidence at this level. You will probably also not see a consumption of antifreeze either. This would be my next step before changing anything.

Customer: replied 2 years ago.
when the car sits at idle it will not overheat. it only overheats when its driven. I only have water in the system now. Can they do the gas test with only water in the system?
Expert:  Tool Hut replied 2 years ago.

If it doesn't overheat idling this probably isn't problem. I would check outside of radiator for it being plugged with debris. It could also be condenser plugged externally restrictions air flow. Stick your camera in between radiator and condensor.

Customer: replied 2 years ago.
I will check it over. Found a rental tool to check gas analizer. Will get back to you when I check over both.
Expert:  Tool Hut replied 2 years ago.


Expert:  Tool Hut replied 2 years ago.

Did you figure anything out?

Customer: replied 2 years ago.
No. Gas test was negative. Radiator tested good. Replaced water pump. Still overheats. It's as if it is in vapor lock and an air pocket is stuck around water pump and it will not circulate coolant through engine. Am very frustrated!
Expert:  Tool Hut replied 2 years ago.

IT is very possible it has a vapor lock. The best way to move the vapor lock is with vacuum. There is a tool called an air lift. a lot of the quick lubes have a coolant flush machine that puts the system into a vacuum and could move the vapor lock.