bc9999

My e60 520 clocked 51,000 km.3 months ago the amber temp light appear while driving 200 meters to my house. The amber light then changed to red. Switched off the engine. I discovered the water expansion tank cracked and leaking coolant. had it changed. Started the car, only after about 10 minutes in idle, the amber light iluminated, followed by red. BTW i changed the waterpump about 3 months prior to this. An hour later started the engine again, same thing happened.No water present in the engine oil. No oil present in coolant. However the electric fan DID NOT turn at high speed as it would normally. S0 i thought it must be the fan problem. So i fitted a new electric fan. Sad, it was still the same.

New finding - The water hose next to the thermostat housing was HOT. But the lower water hose was almost at ambient temperature.!
My narrowed down thought now is:

bc9999

Sorry i pressed the wrong tab.
My guess is either a faulty thermostat or a blocked radiator. any thought please?
Regards
Ham

bc9999

Forgot to mention. I changwd the coolant expansion tank and bled the system a number of times. No coolant lost when red light iluminated.No symptom of trapped air in cooling system.

rctmthouse

If I were you right now is remove the hoses and drain out the coolant; flush it with water and let it drain out completely. Install the hoses again and make sure it's all tight. Follow the coolant refilling procedure and see what I drive say this time. May be access the engine temp on the idrive to see how high it goes. Possible faulty thermostat but when I replaced my pump and thermostat, one of my hose was hotter than the other but after refilling it and let the engine idle for awhile, it went back to normal. I guess it took awhile for the engine to reach certain temperature before the fan and all those temp sensor to work properly.

GL

bc9999

I changed the thermostat yesterday. Still the same problem. I now need a handy coolant refilling procedure.. Thanks.
Ham