Engine Cooling problem
2002 Buick Rendezvous 6 cyl All Wheel Drive Automatic 110000 miles
my wife has a buick rendezvous. I few weeks ago she called me and told me that her engine overheated. So we took it to a shop who looked at it and said it had a blow head gasket and also needed a lower intake gasket. Wanting 900 bucks to fix it I decided to get a second opinion. The other guy that looked at the car said that he could not find any leaks anywhere and thought that the thermostat was sticking and I could use a coolant flush. So all new coolant and thermostat and I drove it a halfhour home and it was fine. The next morning my wife goes to work and she has the same overheating problem. I noticed that there were alot of gunk in the resouvoir and in the radiator cap. I flushed the radiator 3 times now. Each time it seems fine for awhyle the heater is blowing hot and then it does the same overheating crap again and the heat gets cold. I think something is getting clogged in the heater core but dont know how to fix it. Anybody got any ideas on what to do?
Here is what I need you to do. I have a feeling someone mixed dexcool coolant with a different type. Remove the thermostat and flush it until clean water comes out. Next, disconnect the heater core hoses and flush the heater core in both directions.
When replacing the coolant, make sure you use the proper coolant. I believe they make a GL5 which is universal and can be mixed with all coolants. That is what I would recommend incase there is any residual coolant left in the engine / core.
If this doesn't help, then chances are you have a head gasket or intake leaking. Also, make sure the coolant doesn't have oil or ATF mixing with it.