97 528i overheating

My 528 is overheating. It is fine while going down the road but at long stop lights or if I put the car in park the temp starts to raise. I think it may be the themostat but not sure, any suggestions?

I think your car has air in the cooling system, the E39 528 That I have also experienced the same thing. The thermostat doesn't work like it should when there's air in the system, and when this occurs then your engine will then over heat. I believe it just a very bad design on the the engineering part, it wasn't thought out well, and very easy to fry your engine just like that

The trick is when your engine is over heat, pull over let it cool for ten minutes, then start to bleed the bleeder valve on the top left if you look at the radiator from the front of the car. This will remove the trapped air. But don't forget to top your cooling water as soon as you can get them.

Now, this is assuming that your electromagnetic clutch fan, your thermostat, and your radiator and your water pump are working properly.
One other note, I heard that BMW's water pump are known with defective plastic blades, the plastic blades eventually looses its rigidity and then fails to give the cooling system the adequate flow. make sure you get a metal one if you ever need one.

Alex

Correct bleeding IS the first step but difficult on E39's........you need to have coolant coming out both bleeder [next to the rank cap and on the thermostat housing!!!

I usually suspect the fan clutch if the car overheats while sitting still but not while flying down the interstate.
Flunky

I had the exact problem with my 98 528. It ended up being the water pump. Initially the dealer could figure out the problem because it was totally random. As a matter of fact it stopped for months without any problems. However, I had to have the water pump replaced.