Mechanics

CHEVY

1999 Chevrolet Malibu

Engine Cooling problem
1999 Chevy Malibu 6 cyl Front Wheel Drive Automatic

I have a 11/99 Malibu. It started to overheat while driving on the highway. I replaced the thermostat and water pump. Tried to flush out the system as best as possible. Blew out the radiator fins. Confirmed that the cooling fans came on at around 220-230 degrees and that they were spinning at a good clip. Replaced the radiator cap and topped off the coolant. Checked for coolant in the crank case and looked for white smoke from the exhaust. I drove the car for 1 hour on back roads at about 40 MPH. No signs of overheating. The next morning the car was driven 5 miles to the highway. Once at highway speed (55 MPH) it overheated again. The coolant is blowing out of the res. Overflow tube. Any chance there is some bleeding issue or maby the radiator is partially plugged and can't cool the water while the engine is spinning at faster RPM's while on the highway?
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Urx04jv
June 3, 2009.



Sounds like the cooling fan is comming on or a blown head gasket, or all the air is not out of the coolant sys.

Brian 1
Jun 3, 2009.
When I bleed the system I first get air from the bleeder then water. Is there a special proceedure to follow to bleed?

Tiny
Urx04jv
Jun 3, 2009.
I also noticed that the interior heat blows cold when the temp gauge spikes real high then it blows hot when the needle comes back down!

Tiny
Urx04jv
Jun 3, 2009.
Thats a sigh of air in the system, what I do to bleed the sys is open the bleed screw at the housing above the water pump, fill the coolant until it comes out of the bleeder, then start the car with the rad cap off, let it run until the temp gets to about 200 degress, then shut the car off for 3-5 min, it will boil the thermostat open and suck the coolant in from the overflow tank, start it up let it run check the guage, put the heater on hot and full speed, as its running the upper rad hose should be VERY hot which means the t-stat opened. Then top it off let it run make sure the coolant fans come on and watch the temp. Post back with any other quaetions.

Brian 1
Jun 3, 2009.
Do you have a pic or diagram where the bleeder screw is at. I see a screw on the housing but it doesn't look like a bleeder screw, but it has a blue paint on top of it.

Tiny
Hms1018
Mar 2, 2011.