Geez guys...this car has been plagued with an overheating issue...please tell me if this sounds like a thermostat, and not something else like WP or radiator: Temp gauge fluctuates from dead center normal to HOT, periodically...regardless of speed of the engine, or the speed of the car...fan clutch recently repaired, low coolant indicator is displayed 'sometimes', but I don't have to add much, and it doesn't appear to be leaking. Turning on heater in the car doesn't seem to have much affect on cooling temp
Since your 530i is 7 yrs old I'm assuming you have at least 60,000 miles on it. If the water pump has never been changed, this is the time. They are notorious for going out anytime past 50k. Here's what I'd do: change out the water pump, thermostat and while you're in there put new belts on. Let's us know how you come out, regardless.
Verify that the temperature gauge is functioning properly and that the sender works just to be cheap. From there, check to make sure that the cooling system was burped properly and that no air pockets are stuck in the system. Do you get consistent and hot heat in the cabin? If you don't you're low on coolant or their is trapped air. There's an all-metal pump with better bearings from Stewart if the pump is at fault. Check all hoses for their condition if the pump is replaced as well.
Thanks Shawn and Nick, I have new information regarding my problem... Guys, thanks for your replies...I have learned that my electric fan in front of the radiator operates when the AC is on...when I had posted this message I had driven the car to my office (about 21 miles) without the AC on...that is when it was periodically overheating...I drove it home with the AC on (and the temp outside 10 degrees hotter) and it never overheated...I watched the gauge like a hawk, I did see a little movement when sitting at a stop light but it quickly returned to normal it is like the damn thing is spooked...so my question is: in your opinions, is something funky with the two-speed fan switch...and is it never going to the high-speed? I tell you, this thing QUICKLY cycles from hot to normal within seconds...does the fan electrically operate the thermostat? Ok so these may be dumbass questions, but my mechanic(s) are claiming it could be a warped head, and I just don't believe it (I hope to hell it isn't)...idling fine, no smoke, oil looks clean.
Might want to also check the fan clutch. Mine sent out, but was fine until the car sat in traffic, then it would over heat. Visually the fan was spinning, but you could stop it with your finger or any other object. You also didn't hear the fan when the engine was rev'd. Now I woldn't put a finger near the fan, and you can def. heat it when the engine is rev'd.
