[Cyberbach]

OK, I decided to send for the brush kit from Kent Burgsma at mercedessource so I could replace the worn brushes in my blower motor from my 81 240D. The fan would just spin down when you turn it on and it had all the telltale signs of worn brushes. The brushes come with a very comprehensive manual that is well written with step by step instructions except.......... my motor is upside down!!

First pic, screw caps removed and just started loosening the passenger side lower dash panel to gain access to blower.

Bottom cover removed showing fan housing.

Close up of fan housing. You can see the 8mm screws that have to be removed to lower fan and the power plug that has to be unplugged.

The fan has been removed and ready to take to the bench (or in my particular case, to the wifes coffee table)

Removing the square plastic cover over the electrical connection.

Cover removed. So far everything is just like it is documented in the instructions.

End cap of motor housing showing the tab "swells" that had to be pounded back to allow the cap tabs to clear the slots so the cap could be removed.

OK, here's where it gets weird. Removing the cap is supposed to reveal the brush assembly but on my motor the brush assembly is on the other side. You can see where the electrical wires go... so now what do I do?

Here is the picture provided by mercedessource. It shows the brush carrier on the side of the motor opposite the fan side. You'll notice the difference between mine and the one pictured.

So now what do I do? Has anyone tackled this DIY before, I will call mercedessource tomorrow and see what they suggest. Just my darn luck.

 

[akimball442]

Remove the squirrel cage (can be a pain.. mark where it goes) and remove the armature. It should slide right out now...

It's possible that the top half comes apart like the bottom half. That motor is an oddball.

Brushes should still work fine though.

 

[MBZ300CD]

That's the old style motor. His book is based on the new. But good news... the brushes are the same. As for the removing the fan, I've been told to use wood blocks to support the cage, use a punch on the shaft and hit it with a hammer.

 

[Cyberbach]

Remove the squirrel cage

Exactly my first thought when I took the end cap off, but how do you get it off? It looks as though it was "pressed on" as the center shaft is visible at the end and no set screws in collar.

 

[MBZ300CD]

OK... I Just tested this with one I have, it worked great. First note or mark how far th shaft is into the cage, then prop it up on a couple of wood blocks, use a punch and a hammer on the shaft and hit it a couple of times. on the one I did the shaft is knurled. Don't be afraid.

 

[Cyberbach]

Oops, didn't see your post there Gary, I guess I could try that. Probably best to tap the end plate back on first. I guess the worst that could happen would be crushing or cracking the fan assembly but it sure doesn't do me any good the way it is now.

 

[Cyberbach]

First note or mark how far the shaft is into the cage.

Wouldn't it just be considered flush, I'm not sure how you would measure it any other way.

 

[MBZ300CD]

Wow, practically real time forum team repair work.

Wouldn't it just be considered flush, I'm not sure how you would measure it any other way.

From your picture it looks flush so when you put it back on make it flush. It goes back on easy too. I just did it, easy taps.

 

[Cyberbach]

Thanks, I'll try it tomorrow. I used a pneumatic hand piece to flatten the swells that held the end plate on and I'll use it again to put that end cap back on. I'll probably have to remove another end cap under the fan so I might as well just do the whole procedure at my shop. And here I thought I was going to knock this out in my living room, Ha

 

[Cyberbach]

Before I put the end cap back on is there anything I should do to it first, clean it up and put some grease in the bushing?

 

[lxwlxw]

Don't want to hi-jack but let me ask a question, Which parts of this process are responsible for squealing sound from blower motor?

Will the replacement of contacts solve problem or does oil or grease need to be applied to some part of the motor?

I'll be do this same repair soon.

Thanks

 

[mrbenz7]

The bushings or bearings at either end of the motor should be greased. I used High temp wheel bearing grease in mine once I got it apart. The only other thing i could think of was to thoroughly clean the motor with Electramotive cleaner. Just make sure it is for cleaning electric motors!!

If it is not, you will remove the enamel insulation jacket off the wire and your motor is toast!

 

[Cyberbach]

OK, next day. Onward with the repair............

Sunday evening and I'm down at the shop trying to finish this blower repair. First things first, I had to replace the motor end cap that I had pried off yesterday. Since the brushes are located on the other side of the motor this was an unnecessary step but it did give me the opportunity to grease the bushing.

You can see where I pounded the "swells" back down locking the end cap inside the housing.

After reading what MBZ300CD wrote about the fan removal I decided to go ahead and see what further damage I could cause. Fan came off without a hitch although I had to strike the punch multiple times to get it loose, but it did slide out exposing the armature.

The brushes are attached to a heavy copper braid that is crimped onto another lead. Everything I've read said that this wire would be soldered to a contact but this IS one of those oddball motors... go figure.

This is what the crimp looks like when it is removed and straightened. If you've never messed with one of these before, they are a pain and would be easier to just replace with a new one but it was Sunday evening, I had to re-use them.

This is a close up of the brush assembly and the metal crimp before I started mess'n with it.

Notice how the whole arm is on a pivot and spring tension holds it to the commutator. This "oddball motor" is actually probably easier to work with as the pivot on the arm allows removal and refit of brushes without having to separate the whole assembly.

This image shows the old and new brushes. Notice how much thinner the base of the old one was compared to the replacement. Looks like it gunna have to be fitted.

Millimeter gauge, flex shaft with mizzy wheel, draw file and tweezers.... implements of destruction to affect the fit.

And this is how the replacement brush looks once it is cut down at the base to fit inside the brush carrier.

 

[Cyberbach]

New brush installed into carrier and crimp re-applied and wire cut to length. Looks huge!

Notice the second brush wasn't worn near as much as the first and you can see the original stepped design.

And lastly, you will notice that after I put the crimps back in place I went ahead and soldered with a little rosin core just to be sure.... I hate re-using those crimps.

All in all, this wasn't that difficult, it was very messy with all the graphite from the worn brushes and a bit frustrating when the manual failed me due to having an "oddball" motor but I would easily do it again if placed in a similar situation. I've got the housing all put back on the motor and the fan blades driven back onto the shaft, now I just need to get my daughter to stop driving long enough to allow me the chance to bolt it all back in place.

 

[Cyberbach]

************* UPDATE ***************

Just a quick post to finalize this thread. My daughter stopped by tonight so I screwed the fan assembly back up under the dash and put the lower cover back on, (need a couple screw caps if anyone has any extras laying around?). I turned the key on and turned the blower to its low setting ...... viola! ..... it blew! Next, medium speed.... and the fan sped up a little more, turned it on high and dust shot out the vents!! This fan ROCKS! I couldn't believe those brushes and a little grease would make that much of a difference but this feels like a whole new fan.

Another DIY finished, saved a few bucks but more than anything else it's comforting to know that the job was done the right way and the integrity of the car has been maintained.

Now I still have to tackle that pesky window switch..... Cyberbach

 

[MBeige]

Congrats! Like I told you before, this is a good DIY thread. I hope you won't remove the images from your gallery, or convert them to attached images so the threads can archive them too.

Sometimes I get picky and anal and write a note on a piece of tape that I stick on to the part the mileage and date I performed the repair...

 

[Cyberbach]

Sometimes I get picky and anal and write a note on a piece of tape that I stick on to the part the mileage and date I performed the repair...

What a great idea Patrick, wished I had thought of it earlier! That poor 240D would be covered in tape notes though.
Confessions of the nick picky anal bunch:
I have saved every single part I've ever replaced on my "fleet" except most of the sheet metal and a few filters. Most of the parts tell very interesting stories, couldn't just throw them away.... weird huh?

 

[IQ678]

My blower motor is starting to get weaker, so I think I'll be tackling this job once it quits snowing around here...

And Pat - we're much too alike! I also jot down the date/mileage of the repair and also put that in my log book as well.

Congrats! Like I told you before, this is a good DIY thread. I hope you won't remove the images from your gallery, or convert them to attached images so the threads can archive them too.

Sometimes I get picky and anal and write a note on a piece of tape that I stick on to the part the mileage and date I performed the repair...

 

[mountainredneck]

same here... i write down with a sharpie all engine repairs/services under the hood. i also save alot of used parts. i dont know why????

 

[Rmac58]

Very good write up, thanks.