Bmw 2005 Overheating

Last week I had a bad leak in my coolant reservoir which subsequently caused my car to overheat. I took it in right away and they did diagnostic testing and determined there was no engine damage (such as gasket), however both the coolant container & the radiator had cracks and they replaced them both. I picked the car up Thursday evening and there were no problems when I drove the car Friday & Saturday. Today, I drove it on the highway (approx 25 miles) and it started to overheat again. When that happened, my air conditioning blew out warm air. Occasionally the engine temperature indicator would cool back down to normal and the air would be cold again, and then just as suddenly it would creep up to hot and blow warm air again. What is causing this now?

I Know the Answer!

I have the same question
Request More Information

Current Answers

Answer #1: Posted by TexasDeviL on May 5th, 2013 2:01 PM

This answer was accepted by the poster of the original question.

TexasDeviL

Member since:
December 27th, 2012

Points: 960,825

1,100
points

Never drive a car that is overheating. If the needle climbs, pull over.

The system wasnt properly purged of air. You were experiencing air in the cylinder heads. Fill your car with coolant, leave the cap off and watch it for 10-25 minutes. As the air comes out the coolant level will drop, add more coolant. When the coolant level stops dropping put the cap back on. Your mechanic got in a hurry and didnt do this or didnt do this long enough.

If you agree that the answer I provided is correct please remember to "accept" and/or mark it as "helpful" so I know I'm doing a good job. Thank you, I would really appreciate it.

[automotive mechanic and phone modding enthusiast]