Why is my car still overheating?

Hello,

So i have a 1997 BMW 528I. I have had it for over a month now, and it seems to have an overheating problem. I notice that if i am stopped at a light, it starts to over heat, but once i accelarate, then it goes back to normal. I have to keep doing this all the time. I took it to a mechanic, and they replaced the thermostat, and full radiator flush. Before this mechanic, i also noticed that my heater was not working either. Once the mechanic got done me his job, everything was working again. Its been two weeks since then, and now SAME problem again. And now my heater doesnt work also. Can anyone help me out here??

Possibly too much air somehow got into the system. If you had work done at at shop, i recommend that you bring it back to them for warranty service. If you choose to work on it yourself search the site for bleeding air from the system, this link is helpful.

http://www.bimmerfest.com/forums/sho...d.php?t=558386

Other then excess air in the system, it could be many other parts that are causing overheat. Fan clutch, water pump, etc etc. Spin the fan clutch fan when car is cold, if should have resistance and not spin freely. Check for leaks within the vehicle. Search the site as well, this topic has been covered more times then a pizza with pepperoni.

Have you been watching the coolant level? Have you had to add any?

Possible that the car had some cooling system work before you bought it, and it wasn't bled properly (the six is very difficult to bleed, and s/b done by a BMW specialist).

The lack of heat is a tip-off that there is air in the system. If you are losing coolant, there is a leak, which allows air in.

The M52 is not difficult to bleed. People should stop perpetuating this myth, this discourages people from trying to work on their cars. It is very easy to bleed the system, child's play. I never wrenched on any vehicle before I got my e39, and I never found bleeding the system difficult.

You are truly an amazing man. Most of the inexperienced here have difficulties with this task, and the more august members here have developed methods the ensure proper bleeding.

Originally Posted by bkgreene39

The M52 is not difficult to bleed. People should stop perpetuating this myth, this discourages people from trying to work on their cars. It is very easy to bleed the system, child's play. I never wrenched on any vehicle before I got my e39, and I never found bleeding the system difficult.

totally agree....i bleed mine whenever required with nil issues at all.simple and straight fwd.

Originally Posted by moots

totally agree....i bleed mine whenever required with nil issues at all.simple and straight fwd.

+1 I need to say (because I've spent a lot of time with the M52). Bleeding on a hill is nice but not required. On the '97 it is critical to see the fluid coming out of the bleed screw on the upper hose (T-stat housing). I think most people are just filling to the expansion tank line and that's not a sufficient check.

I think the coolant issues on the e39 mandate going to NPG waterless, for low pressure. I've been running it for years on two e39s and it's great.

Stopping at a light and seeing the needle go hot, then cool when moving - classic for e39. First to verify is coolant level, because at idle all the bubbles settle out and the head gets exposed to an air pocket. Next I would be thinking cracked head starting to inject air. After that I think in very few cases the problem is thermostat or water pump, but it can happen.