My 93' 525i still overheating.

[ACir]

I bled air from coolant several times and the changed fan clutch as recommended with no real improvement - the temperature gauge hits the 3/4 mark or higher after approx 5 miles of driving. And the fan still is not working as hard as I think it should at that temperature - I can stop it from turning.

The upper radiator hose feels hot to the touch, but the passenger side of radiator and the lower hose remain rather cold with the gauge reading over the 1/2 mark, and then start getting hot when gauge hits the 3/4 mark or higher.

Is it possible the thermostat is opening, but not enough to cool engine appropriatelly? I can cool engine down to 1/2 mark if I open heater at full blast.

Or maybe the temperature sensor ir reading too high? I have changed radiator and pump within last 2 years so I am assuming they are ok.

Thanks in advanvce for your advice.

[Robin-535im]

Sometimes old coolant is not as efficient at removing heat as new coolant. You might even try straight (distilled) water as a test case. If you already did the pump, radiator and thermostat recently, I would try new coolant before tearing into it.


Robin

[Unregistered]

Thermostats can be very tempramental even from new. If you have any doubts over the thermostat I'd remove it completely and see what happens.

Only other suggestions are flush and reverse flush the system, or could it be the head gasket?!

[mholbrook]

Don't run the car without a thermostat. Not a good thing with OBD cars. Change to a new thermostat or a different one. Make sure you put the thermostat in going the correct direction (not backwards). After the thermostat opens, both hoses should be very similar in the amount of heat. Be sure you remove the bleed screw cap on the radiator and get coolant out the hole when full.

Friend at the race track this weekend tells me that they had to blow through the vent hole to get the air out of the system. Never did this but heard of it.

Hope this helps.

[Tiger]

What is the temp meter reading on highway?

[ACir]

What is the temp meter reading on highway?

[ACir]

Sometimes old coolant is not as efficient at removing heat as new coolant. You might even try straight (distilled) water as a test case. If you already did the pump, radiator and thermostat recently, I would try new coolant before tearing into it.


Robin

[TheGeak]

have you 'tested' the thermostat? i believe there's a process for testing it on Bruno's site.


http://www.bmwe34.net/e34main/trouble/overheating.htm

have you been to that site yet?

[Unregistered]

whats an OBD car?

[Tiger]

Mmm... That means three things... your radiator is kinda plugged externally with bugs, etc... including the condensor for the A/C system... flush them out from engine compartment out with air or water... or your thermostat could be kinda failing... The last thing is your coolant ratio is too high... I suggest 70% water/30% coolant.

You see, at highway speed, engine fan blower does nothing... the force of the air is higher than what your fan can draw in... and you said local speed is also hot... or hotter... so your radiator is kinda plugged... or your coolant ratio is just too high.

The last possibility is your sensor is wrong... to test this, you would need a high temperature thermometer to find out.

[Dom]

Another way of testing the thermostat is pulling it out, which is pretty easy on the 525i, and setting in a pan of water on your stove with the heat on and checking with a thermometer ( a meat thermometer is good) the temp. when it opens. I think my termostat is rated at 180 deg.