Whistle/Grinding Noise 300E
 

Hey guys. I have a W124 300E 3.0L 1992 model year. Last Friday here in Philly, the temperature plummeted to 15 fahrenheit and has not warmed up much since.

After digging out of 6 inches of snow and creating the night's reserved parking spot, I went to work. On the way back a noise started up. At first, I thought it was my brakes. It continued though as I idled at red lights. Even in park the noise continued. The best way I can describe is to say that it is like a whistle or constant squeaking noise. When I accelerated from a stop my car lacked power and bucked slightly.

The noise seems to be coming from behind my instrument panel or in the center of the car. When I pop the hood for a better listen, it sounds to be coming from behind the firewall.

I had a scare on the highway on Monday with it. As I was cruising down the highway the noise came back. All of the sudden there was a LOUD screeching noise that sounded like metal on metal. I pulled off to the shoulder, contemplated calling a tow truck, but then eased back onto the highway and the noise was GONE.

Could anyone please give any ideas as to what this is? Thanks for your help in advance.

Do you think it could be coming from your hvac blower? Have you tried shutting the heat off to see?

The blower motor is the only moving part behind the firewall

I agree. If its 15°F you must certainly are running the heater. I believe it could be the blower motor as well. The noise might sound like a squeaking hamster wheel or a bird chirping. As far as the car losing power and then bucking, that sounds like an isolated issue not related to the grinding/whistling.

I agree . Definitely the blower motor assembly. You'll have to remove the wiper motor and arm as an assembly, as well as the cowling in front of the lower windshield. Not a real complicated job, but if you plan on keeping the car, install a new blower motor assembly $220.00 , not a used one. You'll only find yourself doing it again. Like I did. ...

Blower motor
 

I bought a new blower motor and used the squirrel cage from the old one cheaper that way. I think the motor is a Bosch

The noise you describe sounds like a worn fan bearing.

Rob