[sbrodecki]

My 2008 550I with Sports package and N62 engine with 66K miles overheated the other day on my wife who stop the car and parked it. I found the Coolant plastic tank split down the side. I replaced the tank, the cap, the sensor and put BMW Anti-Freeze and distilled water back in the system. I bleed the system and drove the car (at night) and everthing worked great. No lights or warnings. The next day was hot 100 F and my wife drove it downtown where she call me that the overheating light was on again. I drove downtown and checked the car out. The coolant tank was full, and I could not fine a single leak any where. The elecrtic fan works great, it increases speed when the A/C is turned on. When the warning light comes on the A/C puts out hot air and when the shut your engine off light comes on the car will only move forward very slowly, shifting very slowly and slowly picking up speed. I drove the car home and on a straight run with no stops the emergency stop light changes to a warning but as soon as I had to stop at lights, etc. the Emergency stop engine light came back on. Does anyone think the Thermostat or could it be the engine programming? Anyone have any ideas what is causing the ovferheat lights when the outside Temp is 100 F?

[KrazyM3]

Did you check to see if you have heat? Also check your bottom radiator hose when your car is warm, that should let you know if the thermostat is working or not. Also make sure theres no damage to the engine since its been overheated twice now. Open you oil cap to make sure there is no water inside.

If you have no heat with the heater on, your water pump is not working. If your lower radiator hose is cool when the engine is hot, your thermostat is stuck closed.

Keep us updated.

[positiveions]

Originally Posted by KrazyM3

Did you check to see if you have heat? Also check your bottom radiator hose when your car is warm, that should let you know if the thermostat is working or not. Also make sure theres no damage to the engine since its been overheated twice now. Open you oil cap to make sure there is no water inside.

If you have no heat with the heater on, your water pump is not working. If your lower radiator hose is cool when the engine is hot, your thermostat is stuck closed.

Keep us updated.

what he said.
BTW, those waterpumps propellers are made out of composite plastic. I would take it out and check it.

[3002 tii]

at least on the n52, the elec waterpumps have been known to crap out as early as 60k but typically no later than 100k.