e34 m20 overheat

[Hypr5]

Hey guys

After my car sat for a weekend, I started it up and within the normal time it takes to warm up, I noticed the temp climbing just a bit above the middle mark. As I stopped and waited at the next light, it started to climb to the 3/4 mark. I drove off as soon as the light was green and pulled over (it never exceeded 3/4) and as I started to drive it cooled down RAPIDLY. I idled it for a few sec as I had it pulled over and it started to climb again.

I noticed that it will begin to overheat anytime engine speed is low. If im going 50mph, at idle speed, it will warm up. If I'm idling, but rev to 3k or so, it will stay cool(er) but still above normal by a small bit.

The fan clutch blows a good deal of air even at idle speed, so I eliminated that part. Any ideas on what else could cause this? After I drove it home - I begain to smell coolant and it developed a new leak (maybe from the heat?) but it leaks just above the ac compressor and onto it. So now I really am afraid to drive it.

Any ideas at all on what may have started all this trouble?

Thanks a bunch!

[Reuben Lim]

If your clutch fan is ok, something may be wrong with your aux fans. Have that problem too, weather here really hot. Check your fuse box, for me on left side (US version), to see if either of two aux fan fuses are blown. If those are ok, then check/clean radiator, hoses, do coolant change (distilled plus original bmw coolant). Hope its not the water pump but from my experience when that got broken, car would rapidly overheat to point one of hoses would get blown.

[emw525E34]

Looks like hose leak from somewhere or plenty of air bubbles in the system. First thing is to ensure that there are no leaks and that the water pump is functioning.

M20 motor coolant fill procedure is tricky. You need to REMOVE the top hose from radiator to the top of the engine. Fill that with 50:50 distilled water and coolant mixture, when it over flows, put th hose back and clamp it tight. Then fill the radiation again until it is full. Close it warm up the car and bleed bleed using the plastic bleed screw just next to the radiator cap. Once you get coolant coming out tighten the bleed screw, you are done. Test it, let engine idle for 15 mins and check the temp guage. It should not overheat.

[632 Regal]

I agree with the air pocket scenereo, sounds like the obvious culprit. Bleed her down with the the procedure. Smart man in not driving like that!