Hi ive just changed my thermostat, and now my car is overheating. 2004 BMW E60 525i manual code showing P0599 amongst other codes. Ive been on the car all day and cant work out whats wrong. Any help?

 

Airlock?......you tried bleeding it and checking for any cold hoses?

 

My first thought. No bleed screws on this system though? Left the car running with the heater on high temp and cap off with no problems, left it for about ten minutes and put the cap back on. Turn the temp onto cold and leave it on idle, within 3 minutes its showing as overheating. My first thought was faulty thermostat, but when putting the new one on i didnt click one of the hoses on properly so all the coolant came out. Not sure if there is a certain way you have to bleed the system on this model but ive tried and cant?

 

[font="'Comic Sans MS"]the diesels have a bleed screw on the egr thermostat, without that I'm pretty sure it would have been a ball ache to bleed. Have you tried parking uphill to coax the air out? Have you felt the hoses as Mother mentioned above? ALSO, feel the top and bottom hoses of the radiator. ALSO, check to see if the fan spins up on cue. ALSO, check your coolant temp with the OBC menu.[/font]
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[font="'Comic Sans MS"]P.S. Why did you change the thermostat in the first place? Petrol engines have plenty of excess heat and don't usually need their thermostats replacing...[/font]

 

Was getting a code p0599 thermostat heater control circuit high, so thought i would change it. Wish id never bothered now. If the car was cold then once upto temp, should the bottle boil over? When ive left cars in the past it never has.

 

bottle boil over?

 

The water bottle/expansion tank with the cap left off.

 

You need to bleed the air out of the cooling system. The bleeding procedure turns on the electric water pump for about 10 minutes by following a certain sequence e.g. ignition on, set temp dial to max etc.
I can't remember the sequence but I know it's on the forum.

 

Not sure if it is electric? I thought it was a pulley driven pump? Maybe im wrong.

 

You are getting a return flow though, right?
After your initial fill up, did the level drop down (it should do, as the first switch on gets rid of the air, which you can see as bubbles from the small return flow pipe.