i have a 92 300d 2.5 with 181k which is making a little noise behind the passenger air bag. it is a constant hum, which sounds a little like static. when i disconnect a fuse (i think it was 7, it was the one the auxilary water heater is on) the noise stops. the noise doesn't change with different speeds, nor stop with highway driving.

this car also didn't get up to temp this winter. at barely creeped past 40 if i was driving on the highway, and couldn't get to 60 if i warmed it up in the driveway, and only drove on backroads. i figured the thermostat was bad, and have a replacement. now that it is warmer, the temp got up to just under 80, and i'm thinking maybe the thermostat isn't bad after all.

i need to mess with the coolant as i'm putting in a veggie kit, so i'll replace the thermostat anyway, and check the old one with some hot water, but i'm interested in the noise that might be from the water heater. any thoughts?

thanks

david