Oh hello, number 8.

[Shern]

Second blown fuse in about 7 months. Melted at the terminal.

Pulled the blower fan from my 240D, have disassembled it for inspection, subsequently realized, I've no idea what I'm looking for.

Below are photos of the brushes in their current state.
In your opinion do they need replacing?

Also below are photos of where I think I should put a few drops of bearing oil/grease/texas tea.

Thoughts?











upload image online

[Diseasel300]

You have the lube points correct. Only use an oil designed for electric motors. You can get something like 3-in-1 in the blue can, or preferably Zoom spout oil. Don't use grease or engine oil or you'll ruin the bearings. Avoid WD-40, it isn't a lubricant.

The brushes look ok, you might take compressed air and blow all the dust out of the windings.

When you replace the fuse, take the time to clean the fuse holder well. Make sure the fuse you put back in place is a copper or brass fuse, skip the aluminum fuses.

[Shern]

Roger that. When I bought the car, I swapped all the fuses for copper. Given that the brushes are passable, and provided the fuse holder is clear, I'm really hoping a bit of bearing lube will get the job done.

[strelnik]

Originally Posted by Diseasel300

You have the lube points correct. Only use an oil designed for electric motors. You can get something like 3-in-1 in the blue can, or preferably Zoom spout oil. Don't use grease or engine oil or you'll ruin the bearings. Avoid WD-40, it isn't a lubricant.

The brushes look ok, you might take compressed air and blow all the dust out of the windings.

When you replace the fuse, take the time to clean the fuse holder well. Make sure the fuse you put back in place is a copper or brass fuse, skip the aluminum fuses.

I had similar problems once with a 240D blower motor. Used a rubber eraser to clean the windings and then used DRY AIR to blow everything out. A lot of gunk in there over time because there's no cabin air filter and Detroit is a dirty city.


Someone once told me that there's a diagram for lube and cleaning for the blower motor but I have never seen it.


Anyone on the forum know where this is? I'll put it together and submit for a sticky if you do


Thanks

[Diseasel300]

Mercedes apparently had a lot of problems with blower motor fuses. To the point that in the mid-1986 model year they switched to an external 30A fuse holder for the blower motor. The FSM makes a big deal about the "June 1986" change to the wiring to accommodate the new fuse holder. My car was built July 1986.

If you keep having issues with the fuse melting (instead of blowing), you might consider just moving the fuse external to the fusebox and using a 30A ATC style fuse in an inline fuseholder.

[compu_85]

IIRC they had a TSB about this, and I know they sold a retrofit kit for the external 30a strip fuse.

-J

[Shern]

What's the issue with using 3-in-1 in the red can?
I've been to shops all morning. Finding electrical motor oil on a shelf is impossible.

[Diseasel300]

Red can will turn to varnish in the bearings when subjected to friction.

Go to Home Depot or Lowe's, they have 3-in-1 in the blue can where they have the WD-40 and other lubricants in the tool section.

Or if you're lucky enough to have a proper hardware store, they will have Zoom spout oil, which is fantastic stuff for anything needing oiling.

[Shern]

Lowes had it. Negative on Home Depot and every single autopart shop/hardware store I visited.

The good news is that a little lube on those bearings has really made a difference in fan power. I was not expecting that.

[Diesel911]

The Fuse upgrade is not for the W123.

On fuses with plastic bodies the plastic melts before the metal fuse strip does. Use Fueses with ceramic bodies and copper or brass metal strips.

The bronze bearings on the Motor are the oillite type which means they were made with powered metal that was compressed and then soaked in Oil. The Oil is supposed to fill in the cavaties. Over the years that Oil evaporates. 3 and one Oil, Sewingmachin Oil and thin gun oil will all work but you need to drip some on and let it soak in over night and repeat over and over till you believe the bearing is satureated.

When I took my Blower Motor apart the insids had a lot of crud some of which drug on the rotor making for a slight resistance when you turned it by hand.

The motor on mine is not a Bosch one it is a Seimens.
On mine I had to drill out the rivets to gain access to the ball bearing so I could repace it.
In the pic you can see where I center punched the rivets.
I used pop rivets to replace the rivets and also epoxied the bearing retainer plate down.

[Shern]

Very useful... thanks!

[JHZR2]

Originally Posted by Diesel911

The Fuse upgrade is not for the W123.

I definitely had the fuse upgrade done on my 83 300D.

[Shern]

You know, this actually ended up being the ignition switch.

I blew a couple more fuses here and there and then finally, it wouldn't turn on.