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Tom, ASE Certified Technician
Category: Car
Satisfied Customers: 25920
Experience:  ASE Certified Master Technician
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98 oldsmobile aurora: overheating..cooling system..a compression test

Customer Question

my 98 oldsmobile aurora is overheating. i replaced every part of the cooling system and performed a compression test, now i'm lost. any suggestions on what is causing my overheating problem? is this a common problem among 4.0 northstar motors?
Submitted: 7 years ago.
Category: Car
Expert:  Tom replied 7 years ago.
Which parts did you replace and does the fan operate
Customer: replied 7 years ago.
replaced the waterpump, thermostat, heater core, heating control sensor, upper and lower radiator hoses. flushed the radiator and the cooling system. performed a compression test. yes, both fans are working.
Expert:  Tom replied 7 years ago.
OK has it been checked for a headgasket even if the compression is good the gasket could still be bad need to have it checked for hydrocarbons very common on these motors for headgaskets to be bad causing the overheating issue
Customer: replied 7 years ago.

please give more info on hydrocarbons, are you saying that hydrocarbons are/might be getting into the cooling system causing the overheating?

Expert:  Tom replied 7 years ago.
What happens is when the head gasket is bad it allows exhaust gasses to mix with the coolant causing excessive heat and air pockets causing overheatin need to bring it to a shop and see if the hydrocarbons are excessively high coming out of the exhaust also there is a kit where you can get a reading out of the top of the radiator sounds like a bad headgasket possibly both this is the next step to take
Customer: replied 7 years ago.
ok that makes sense, is this a common problem among auroras? thanks for your time and opinion.
Expert:  Tom replied 7 years ago.
Yes very sorry for the bad news