overheats

[jagheer]

used 96 328i. I live in CA in the valley outside temp goes into the mid-90s. When I have the AC on, and am sitting idle for >3 or so minutes the temp starts to move close to red. I have to turn off the AC or turn heater on? The radiator has been replaced. Could it be aux fan? (replaced in the past) sticy thermostat? water pump? Taken vehicle to non dealers and they say everything is fine.

[Speedy-325is]

air flow in hot weather is helpful. my cars dont like to idle in the LA heat either. possibly thermostat, is ur coolant fresh, could be fan not kicking on. you might want to probably put a low temp/higher flowing thermostat. i put a 70degree thermo and have had no problems since.

[007ben]

you car likes air moving over it. also may want to be sure you don't have a lotta crud on your radiator obstructing air flow.

[bitcore]

when you turn A\C on, the engine bay gets hotter (heat is exchanged from the cabin to the engine bay) When you turn the cabin heater on, the engine coolant is being used to heat the air for the cabin blowers, helping your car to cool off.

BMW's weren’t meant to idle, A-la-007ben, you car likes air moving over it and yes, do check for bugs and stuff on the radiator. Be gentle cleaning it off, they can spring leaks that you can't "fix".

Check thermostat, fluid level, and if your main engine crank fan clutch is worn out (it's easy to stop the fan [NOT WITH FINGERS! use a rolled up newspaper or something near the clutch] if the clutch is worn out)
there is also a common problem with E36's where the radiator top hose neck will crack. Mine cracked and BROKE off, ruining the radiator and expunging all the fluid out of my cooling system onto the road. That sucked.

[jagheer]

The radiator is brand new. Why would the fan occ stop working at idle and then be fine when I am on the road.

[007ben]

its not just the fans..

moving the car moves that much more air to cool the car that much better...

[bitcore]

96 e36 dosn't suffer from plastic impellor problems on the waterpump, right? wasn't it 95 and earlier?

Once again: Check thermostat, fluid level, and if your main engine crank fan clutch is worn out.
Sitting idle with the A\C on is probably the hottest thing to do with your car, other than driving at redline with the gas floored, but then you have extra airflow around the engine.

[jagheer]

I just purchased some brake light holders and a BMW mechanic was getting some parts so I asked him the same question and he thinks the fan clutch or accessory fan is the problem. So I bought the part and I called my mechanic to just replace it. Wish me luck. Thanks for all of your input.

[Kevin325i]

Let the car idle in your driveway. Get to operating temp. Turn the ac on full blast. And go look if the auxilary fan is spinning. My money is on it's not kicking on.

Kevin