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Waterpump/Thermostat..overheating issue on X3 35i
i too experienced the sudden and unexpected issue with Over Temp warning light and de-rate occurring. happened in rush hour traffic stuck in the left turn lane, definitely no fun.
Read all the threads, did some diag. on my own. I am a life long mechanic, and i'm still in the service business on the Heavy Truck side. My Son is a Mechanical Engineer and a good Technician in his own rights. He helped me with both diagnoses and tear down.
Confusing part, without a/c on engine would not over heat in normal driving, with a/c on would go about 5 miles, light on, de-rate without fail. could initiate the w/p air purge test and the pump and the fans would come on at high speed and pull heat from radiator. at any rate came to the conclusion either w/p or T-stat were malfunctioning causing lack of circulation.
what i wanted to share with the group is on tear down this is what i found, w/p was original equipment and appear to be working fine. T-Stat also original. we disassembled T-stat and found it to be frozen or stuck closed, T-stat would not move off of seat, brass thermal collar was hard fast frozen to stainless axis pin. I suspect at 103 Celsius any delay in opening would be a problem especially here in S. Texas heat.
it is a major undertaking, we have 3.5 hours in disassembly, i did remove the fan shroud and turbo heat exchanger from the bottom of radiator assembly, i am doing a clean out of debris while i have it all apart. as mentioned pump will not come out the bottom on the xdrive.
Currently i have all Parts on order, W/P, Thermostat, Mounting bolts, BMW antifreeze, also doing belt, tensioner, and idler pulley at this time. do i need the w/p ?? probably not but too difficult to access not to re-new while here. total dollars at this point $677.50
once i have completed the repair i will report back if condition is repaired
2011 X3 35i xdrive 85,000 miles well maintained
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