Friday, September 9, 2011

1990 BMW 525i overheating?

The bleeder screw is on top of the coolant tank or on top of the radiator. it should be removable with a large screw-driver.

Until you get all the air out you're never going to stop the overheating condition. the easiest way to bleed these things can still be a pain! jack the front end of the car up and start filling the tank. open the bleeder screw and keep going until you've got all the air out you can. after that you need to start up the car (with it still jacked up and properly stabilized) and turn the heater on full heat (both left and right sides if you have dual climate control) keep the cap off the tank while you do this and keep filling it. you may have to crack the bleeder open while doing this as well. when you get all the air out leave it idleing with the cap off. as the temperature comes up you'll see some coolant spill out, that is normal. Watch the temperature gauge while this is happening and you should see the temp creep slowly up toward the normal mark then drop down sharply a bit. this drop is when the thermostat opens and at that point you should be able to add some more coolant. when it is full this time close the cap and bleeder screw then turn off the car. let it sit and cool for an hour or so and then once it is cooled re-open the cap and top off if needed. After that lower the car to the ground and start it. let it run and see if the overheating problem is fixed. You may have to repeat the process once or twice but that should be it. if you're still having problems after this you may have combustion gasses entering the cooling system (usually a symptom of a blown head-gasket or cracked head) This is not the likely problem though and i would try to bleed it properly first.

Make sure you have anti-freeze in the radiator. It circulates better than just water, because water boils and turns to steam (goes UP) proper antifreeze helps it not have pockets of steam/air.