2001 740 IL Overheating after replacing Alternator..

[meyer34]

Just when I thought I was in the clear. Alternator goes bad, end up getting mine rebuilt and putting it back in last night. Now my car overheats after I been driving around 5 miles. I thought it had sopmethin to do with the coolant lvl maybe to high? Cannot see a leak anywhere, Fan comes on??? Any suggestions???? thanks meyer

[Bear]

When you say the fan comes on, are you addressing the electric fan (auxilixary) or the Viscous fan (attached to water pump pulley)? Does she overheat in traffic as well as at speed (above 45 mph)? These cars are notorious for trapping air in the system and needing to be bled,(although I never had this issue with a 7 series). If she overheats only in traffic, I would suspect the viscous fan clutch as the culprit as the engine needs both fans working (properly) to cool at low speed.

[meyer34]

actually we trailed it back to the thermostat, it wasnt opening at all and caused the hose to saty cold as the other hose was hot and hard...getting a new thermostat today for $40 bucks and we will see what happens....it overheats only while driving but will over heat within 1 or 2 miles. it will nOT overheat while idle, we let it run for like 30 minutes and no problems, until i drove it a block.....i will let you know how it turns out...thanks for your reply....

[Bear]

Let's hope it is the "T" stat. Normally iof the viscous fan goes south she will run hot in traffic and at idle but will come to normal at speed. On my '88 750 even high speed on the auxiliary fan would barely keep her near normal in traffic.

[meyer34]

so changed the thermostat and she continues to overheat but not as fast now.....lol, and checked the fan with my own hand and it was really slow and weak, SO, it has to be the fan clutch and i will be getting one tomorrow...we shall see, i still love my BMW.....meyer

[meyer34]

Replaced the fan clutch, worked great for around 30 to 40 miles, then went into a resturant to eat, sat for like 1 to 1-1/2 hours. Well not even 3 miles away, it overheated again!!!!...These are the items replaced: 1) Alt, 2) Thermostat, 3) Belts, 4) Fan clutch, and did the 50/50 mix....Any ideas? Anything would help...Also, the check coolent level light came on! Shoud i take this to BMW, or try to bleed the system? If so, how?

Any HELP would be awesome! And Cost effective (low on funds right now)

Thank you Meyer...