ptbo

My '86 5000s is overheating and I don't know what the problem is.

last week I replaced the coolant temp sender (old one didn't worked since I got the car) and flushed the rad, engine and heater. The flushing seem to go fine, no apparent blockages or rust, and I filled the car with the proper g-11 coolant. After doing this the temp when the car was warm was approximately 110 deg C, but the coolant temp warning light didn't come on. I am not sure what the operating temperature should be since I never had a functioning gauge before. Anyways, after flushing and filling the cooling system with coolant I noticed I had a small leak, it turned out that I forgot to tighten one of the hose clamps, but in the course of looking for the leak I removed the new temp sender, lost some coolant, and then replaced the sender. I subsequently topped up the reservoir to replace the coolant I lost, however after I did this the temp warning light comes on and stays on once the car gets up to it's current operating temp (110 deg C). The rad fan is coming on sometimes, seems quite random, but not as often as it did before I did the work on the cooling system. The fan isn't coming on with the warning light, and doesn't run when the car is off like it used to.

Any suggestions where to start solving this would be greatly appreciated. I am supposed to be embarking on a lengthy road trip in 3 weeks, but I can't go till I get this car sorted. By the way the external temperature right now where I am is about 25 deg C.

Thanks.

ptbo

Just wanted to add that when the car is warm both the upper and lower rad hoses are hot as are both the heater feed and return hoses. I am taking this as evidence that there are no blockages.

mofologic

Air bubble?

ptbo

How should I go about purging air from the cooling system?

Pushbutton_auto

Shouldn't go above 100 !

Remember to set the heater controls to warm when doing the flush.

ptbo

OK, a bit more info, and more questions.

When I did the flush and the fill I had the heater set to high, however I am having some problems with the vacuum heater/ac servo. The motor that pulls the bowden cable doesn't work right, but I thought that this just controls the flaps on the heater box and shouldn't have anything to do with the heater valve. So what does control the heater valve? How can I check if it is working?

Next bit of info is that the rad fan is turning on at the same speed when I turn on the heater fan to either low, high or defrost it then shuts off when I turn the heater fan off. Is this correct? Is it indicative of some problem? when should the fan come on and at what speed? how can I test it?

Thanks.

audiqv8

The fan is a 3 speed fan. Does the radiator fan runs at all three speeds low, med, jet engine taking off? If the fan only runs at either medium and high or just high, then I would check the fan resistor.