'93 525i normal coolant temperature range?

[ACir]

I think my car is running too hot - needle runs 3/4 of the way to red zone, even further in heavy traffic. I recall it ran more towards 1/2 way before. Is this abnormal? If so what needs to be changed? I put new radiator and BMW coolant last year, water punp 2 years ago. I am thinking thermostat or fan clutch. Thanks in advance for your help.

[Tiger]

Yes, it is supposed to be smack dab in the middle.

What was the ratio of coolant to water? I find that 50/50 is way too thick... try 70 water/30 coolant ratio... Just drain some out and simply add water.

Thermostat is faulty only when you see tremendous termperature change... such as when on highway... engine is too cool... come to stop and the temp will surge high.

Fan clutch is a good possibility... easiest way to tell is normal driving over 25 MPH and temperature is normal... and when come to stop or 25MPH or lower speed.... temperature spiking higher. Another easy way to tell is pop hood open and let the engine idle on your driveway... when temp is up there and you feel the fan blowing hard, then it is working.

One other possibility is clogged fins of radiator due to bugs... simply use air hose or water and flush it out toward the front of the car from the engine bay compartment.

So if fan is working and so is the thermostat, then it has to be the coolant mixture. I find engine runs much cooler when more water is added (diluting effect).

[RobPatt 93 525i @121K]

that's where mine is.
New coolant, t-stat, water pump.....
Old radiator, hoses, fans...

How reliable are the radiators, should I change out now, before problems?
121K miles....

Good luck. Rob.

[Tiger]

Radiator is radiator... if it doesn't leak, then it is fine. However, you have to check the fins for obstructions... due to bugs... Not just the radiator but also the A/C condensor... If you cleaned this, then it has to be the coolant.

I personally have done some test lately on the coolant mixture... the temperature difference is huge... 20 degree difference. From 50/50 to 70 water/30 coolant.

[Tiger]

However, I forgot... plastic on radiator usuall breaks anywhere from 75K miles to 110K miles... so for your benefit... change it before it breaks and cause bigger trouble.