My wifes '85 300D has a screeching noise coming from inside the dash. It starts after the A/C has run for a while. If she turns on the defroster, it stops.

I'm thinking it's the blower motor after doing a search. Would you all agree? Do I need to order the one with the fan from Parts Shop?

Liquid Wrench it, then lube it
 

Greetings,

The all famous squeeling or stopping blower motor on these older Benz's. You can replace it if you like or take fifteen minutes of your time and do the following to prolong its useful life. Remove the blower motor housing, then the dome blower blade assembly so just the motor is exposed. I just removed the entire motor from the plastic housing so I could mount it in a vice for easier work around. At any rate once each motor shaft end is exposed I squirted liquid wrench on the shaft and let it soak into the shaft sleeve to loosen up the gunk and rust that is definitely on the shaft and also embedded between the shaft and end sleeve. I added power from a 12 volt battery to turn the motor so I could ensure penetration of the liquid wrench through the length of the bearing sleeve. Spend ten minutes or more on each side flushing with liquid wrench, running motor for 30 seconds or so then wiping off and resquirting it again to bring the gunk to the surface of the shaft. After you feel you have both end sleeves fairly cleaned of garbage, then take your rag and wipe the excess off and use compressed air to push the rest of the solvent out from between the shaft and sleeve. Use a high quality electric motor oil, or use what I did, high temp. lithium oil to be your lubricating oil between the shaft end and sleeve. Once again add a few drops of oil, give it a minute or so, run motor for 10-20 seconds, stop and add more untill is seems not to accept any more, the sleeve should be well lubed by then. About three to four oil applications. In a lot of applications it's not the motor gone bad but lubrication that has left the friction areas, but don't add oil without cleaning the surfaces first, problem will reoccur in a matter of days otherwise. There are no so called sealed end bearings on the older motors, just end sleeves made from copper composites. If you have motor play from end to end, then a motor replacement may be the best option for you. Couldn't see paying $100 or more for a replacement motor when cleaning is all it needed.


Charles

Blower Moter
 

Make sure that you also check the brushes for the motor. If this vehicle is a high miler and you are going to keep the car I, personally would replace it. Not that much work involved. Brian

Look at motor
 

Greetings Bill,


The squeal isn't from the brushes it's from the end shaft sleeves. Non-running motors or those that are intermitent are probably a brush problem. Depending upon the motor installed on your car, it may not even be possible to change brushes. You can't change them on mine, it's an '80 300 model.

Charles

Charles, sorry I did'nt make my message clearer. I meant that wheen the cover is off for lubrication look at the brushes and if they are worn all the way down the motor won't last much longer anyhow. And yes the entire motor would need replaced, not just the brushes. Sorry for the confusion.Brian

Here is a link that may help you.


http://mercedesdot.com/current_issue.htm

Thanks Guys!

Great information.

CJ, ...many many thanks for these info.

A very resourceful info indeed......