Hello,


Last week I replaced numerous parts for preventative maintenance, namely the radiator, several hoses, drive belts, alternator side tensioner, and installed a 90C thermostat. Everything seems to be working fine, but yesterday I was out and the gauge showed it to be running hot. According to my scan tool it was running at 250F. There were no other signs of it running this hot other than what the gauge was telling me. After letting it cool down I checked the coolant level and looked for leaks. The level was fine and, no leaks anywhere. I then installed a wireless meat thermometer at the upper radiator hose (attached it with a few wraps of aluminum tape), and got my IR temp gun. From cold, all the three temps agreed with each other, but after starting it, the temps diverged right where operating temperature should be. The observed temperature at the upper hose was 188-190F according to both the meat thermometer and my IR temp gun. The temperature at the lower hose, as measured with the IR temp gun was 90F. The temperature according to the scan tool however, went all the way back up to 250F. Now, based on all my past experience I have to say the temperature sensor is bad. No where on the front of this engine do I get temps higher than 190F. Do you agree? I have ordered a new sensor, which I understand to be the one on the pump.

__________________
2003 BMW E53 X5 4.4