cooling system question - need help! [Archive] - Bimmerfest - BMW Forums

: cooling system question - need help!

A Rios
05-23-2008, 09:26 AM
The radiator on my M3 was leaking so I just replaced it, my thermostat, hoses and water pump simultaneously. Now the car is getting hot after 4 minutes of driving. The drivers side portion of the radiator is scalding hot and the other side is cool to the touch. Coolant is the expansion tank is also cool, but when I tried to open the cap slowly cold coolant started bubbling up! What is going on? Does this sound like my new thermostat is faulty or the new radiator clogged? Also the water pump is just intalled is a Stewart High Performance pump. Doesn't the slot on the back of the pump point up toward the thermostat? (The OEM pump has no such slot. It's all open in the back) Somebody please help!

05-26-2008, 12:24 AM
I don't have any idea about the Stewart pump but it really sounds like the cooling system needs to be bled of trapped air. If you go to and look under DIY there is a water pump replacement thread that shows how to bleed the system. Best of luck

05-27-2008, 05:45 AM
You have air trapped in your system. The best way I know how to get it out is to take some coolant with you and drive until you see the temp going over half way, shut it off, get out and crack the bleed screw, after the pressure has bleed off put in more coolant. Don't let the temp go much over 1/2 way.

Other method is to get the front end up some like on a couple 2 X 4's and with the front wheels on the 2 x 4's you can run the engine and yes set your heat control to its highest setting and let the engine warm up. Once the t-stat opens it should drop your reservior level. Also be sure you have the bleed screw open. You will need to close it once coolant starts to bubble out. This has been the only successful I have found to get the air out of the car without driving it, filling it, driving it.

If you drive it expect the driving, filling routine to take a couple times.

05-27-2008, 06:02 AM
Don't forget to turn on the heater when bleeding the radiator. This will help purge air from the system.

05-27-2008, 06:02 AM
While engine is running, open the bleed screw and add coolant as the air bleeds out. That is why the bleed screw is there.

06-17-2008, 10:19 PM
Pine Cone nailed it. Air in the system. Let the car cool down and start it up and open up the the bleed screw on the top of the radiator. Air should bubble out for a bit and eventually a stream of coolant. That's when you know the air is out of the sytsem. You will need to put more anti freeze in the radiator once you bleed out the air pocket. So once the system is bled out, close the bleed valve and open the radiator cover. The coolant level should be low. Top off the radiator with coolant while the motor is running. Then open the valve again and bleed off any more air.

That should do it.

06-19-2008, 04:32 AM
Burp the cooling system. Check Peilcan Parts DIY...very handy.

A Rios
06-25-2008, 12:33 PM
:thumbup: You guys were exactly right. Bleeding the system was all I needed to do. Thanks for all your help!

06-26-2008, 11:15 AM
:thumbup: You guys were exactly right. Bleeding the system was all I needed to do. Thanks for all your help!

guys any idea if the water pump, hoses, thermostat and the radiator are professionally done how much it would cost? just want a ball park range....please

06-26-2008, 01:08 PM
$250-300 for parts and around 4 hours for labor at maybe $65/hr. Labor rates vary and some parts will too some but this is a pretty good ballpark....