A: Hi, Steven. First of all, whenever you open the cooling system for service, you want to bleed the system of air afterward. Failing to do so can leave air trapped in the system, resulting in engine overheating.
If you got all of the air out of the system and the engine is still overheating, you’ll want to look at the electric water pump. Faulty water pumps are common on these engines.
You can make sure the water pump turns on by performing a simple test procedure. First, set the climate control to the maximum temperature and minimum fan speed. Then, with the key on and the engine OFF, press the accelerator pedal to the floor for 10 seconds. You should be able to hear the water pump start running shortly after.
But even if the pump comes on, it may be weak or experiencing intermittent problems. So, regardless of the test results, you might want to try swapping the pump out to see if that fixes the problem.
Also, you’ll want to make sure that the radiator cooling fan comes on as it should. The fan will operate at different speeds, depending on coolant temperature and vehicle speed.
I highly recommend that you do not drive the vehicle until you address the overheating concern. The problem could quickly lead to engine damage (if it hasn’t already).
Good luck!
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My 325 I 2002 has a Manuel water pump change everything radiator, water pump, thermostat, n it still hears up quickly ?