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jim, ASE Certified Technician
Category: Buick
Satisfied Customers: 1179
Experience:  ASE Certified A6,A8,L1 and California Licensed Smog Technician
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2000 Buick Century 3.1 ltr with approx 159000kms, overheating

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2000 Buick Century 3.1 ltr with approx 159000kms, overheating after 15-20 mins run time. Antifreeze level is up. oil looks good and clean, no antifreeze appears to be in oil. No white smoke on start up or when running. Car has not been driven much in the last 6 months. While running engine, i watched temp guage. It went up then dropped down a bit, then went up more, dropped back a bit and so on. Cooling fans came on approx 3/4 of temp guage scale, temp kept creeping up untill it went to max temp. Red Temp light came on, engine went into rough idle mode and TRACTION CONTROL OFF light came on. There was heat from heater. Runs great until Temp light comes on. Engine does not seem real hot, can comfortably touch both rad hoses, not hot to the touch.

Any ideas for the cause? Thermostat stck closed maybe? is temp sensor on the engine side of the thermostat?


There is a technical service bulletin related to this problem, I am sending you. If there is air in the system you will need to bleed the air from the system. I would recommend to change the thermostat, do the service bulletin procedure and install a new cap. Then bleed the system of any air. There is an air bleed made of brass usually sits on or near the upper radiator hose inlet on the intake.


Bulletin No.: 00-06-02-001

File In Section: 06 Engine/Propulsion System

Date: January, 2000

Engine Running Hot, Overheating and/or Loss of Coolant (Polish radiator Filler Neck and Replace radiator cap. Models:
1999-2000 Passenger Cars and Trucks with Composite radiator End Tank



Some customers may comment on one or more of the following conditions:

^Engine running hot


^Engine overheating, and/or


^Loss of coolant/low coolant message



The radiator filler neck may have an imperfection in the sealing surface.




Using a piece of 400 grit wet/dry sandpaper backed with a flat piece of wood, polish the filler neck sealing surface using a circular motion.

Replace the radiator pressure cap with a cap of the same part number as shown in the GM Service Parts Catalog.

Customer: replied 6 years ago.

Is there a procedure for bleeding the air out of the system after it has been filled? Do you open the brass air bleed screw (I've seen it) as you're filling the system?

Fill the radiator up and let it run until the thermostat opens and add any more coolant to top it off. Once you know the radiator is full install the cap and open the bleed valve and run the engine until you have a good stream off coolant coming out and then close the bleed off.

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Customer: replied 6 years ago.

OK - Thanks Jim! I'll do these things and hopfully this will solve the problem.


Don, (Pickering, Ontario, Canada)


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