Good Source for Blower Motor Brushes - PeachParts Mercedes-Benz Forum

MarkM · #1 02-08-2010, 10:02 PM

I recently experienced for the first time the blower motor blowing fuse no. 8 when the motor is on high. After much searching for a replacement new motor (I'm in it for the long haul with this car, and I wanted a permanent fix for about $100), I realize that they are simply unavailable at reasonable cost. I couldn't find a new bosch motor alone for my car...only the complete blower unit for over $400! So I found a used motor from a salvage yard for only $25, and decided to replace brushes in both (using one as a backup).

After much searching in this forum, and looking in small parts trays in Ace Hardware, I found a post by UtahPete in this forum identifying www.carbonbrush.com, as a good source for Bosch motor brushes. I bought the K44 brushes, 8 mm x 8 mm x 19 mm long for $5.35 ea. , plus reasonable shipping fee (about $6 and change) I placed the order on Wednesday last week, and on Saturday my parts arrived at home by U.S. Postal. Very good service, good product, perfect drop-in replacement.

The brushes are the exact size, but requiring sanding the contact end to proper angle and curve (I got it close, not too fussy).

It looks like there are three wear points on these motors...

1) Brushes...easily replaced with limited soldering & mechanical skills. I surmise that worn brushes cause an increase in current draw of the motor, causing fuse to blow.
2) Bearings....can't do much about these except to put a few drops of ATF and hope they will last as long as needed. I don't think they are replaceable.
3) Commutator...where the brushes contact the commutator, I observed about 1/16" of wear into the copper commutator on the two motors I have. I don't know how much life is left in the motor with this type of wear, or how much more wear the motor can take.

In the end, I just figured I would replace brushes, lubricate the bearing with ATF, and hope for the best. After brush replacement, the motor no longer blows the fuse. So I hope with brushes replaced in my two blower motors, that these will last for another 100,000 miles (?!?!?!).

I also see the fuse replacement option consisting of the fuse holder and wire allowing you to bypass the fuse in the fuse block (fuse no. 8 is a blue 25 amp), and replacing stock fuse with a 30 amp fuse....hardly seems worth the effort, for such a marginal increase.

Thanks to www.carbonbrush.com and UtahPete,

Mark

ashedd · #2 02-08-2010, 10:06 PM

I gave up and bought a new motor. Be careful because I broke a squirrel cage so now I only have one.. still seems to work fine.

I found something on ebay when I was looking. But the brush kit was not cheap.

Good luck

dannym · #3 02-09-2010, 07:49 AM

Radio Shack?

jfikentscher · #4 02-09-2010, 08:39 AM

There was a post a few years ago. The kit was $29.00. But I can't find it now. I did the brushes fix. Worked good.

mobetta · #5 02-09-2010, 11:58 AM

I brought my old brushes and motor in to a local auto electric shop and got brushes for $5 ea, no shipping.

last I checked, mer cedes source will charge you $30+ for them, but they come with an "instruction manual"

vstech · #6 02-09-2010, 12:16 PM

the problem you are going to realize is twofold.
one, the bearings are the issue with failing fuses, not the brushes. (they cause the brushes to wear rapidly also!!!)
second, the fuse holder upgrade is because, the 17 or 18 amp constant draw is too much for the fuse HOLDER to handle, not the fuse capacity,... the reason for the change is because the brass spring heats up SOOO much that it melts the fuse cage, and leaves the fuse loose, which causes more heat and so on...
the actual 25 amp fuse rarely blows.
beware. if you are melting fuses, you are heating the wires, and the fuseblock, and the fuse very high, and could face a fire if you don't get those bearings fixed. (I.E. change the motor...)
ATF is not a good lubricant for bearings.
clean out the residue, and old grease and get some good bearing grease packed in there.
good luck.

MattBelliveau · #7 02-09-2010, 01:11 PM

************** used to sell a kit. Mods, please forgive me if this is restrictive info. Thanks.

jbach36 · #8 02-09-2010, 05:17 PM

I just bought a new motor for $77, without the squirrel cage fan, made by Bosch.

MarkM · #9 02-09-2010, 09:38 PM

Quote:

Originally Posted by jbach36

I just bought a new motor for $77, without the squirrel cage fan, made by Bosch.

Where did you buy it from? I did a lot of searching and came up empty handed.
Thanks,
Mark

jt20 · #10 02-09-2010, 11:32 PM

ummm Ace hardware and modify their size as others have done.?

dantheman67 · #11 02-10-2010, 01:15 AM

I just nabbed a new blower motor. 123s are plentiful at the local pick n pull.

Hit Man X · #12 02-10-2010, 03:52 AM

Quote:

Originally Posted by vstech

the problem you are going to realize is twofold.
one, the bearings are the issue with failing fuses, not the brushes. (they cause the brushes to wear rapidly also!!!)
second, the fuse holder upgrade is because, the 17 or 18 amp constant draw is too much for the fuse HOLDER to handle, not the fuse capacity,... the reason for the change is because the brass spring heats up SOOO much that it melts the fuse cage, and leaves the fuse loose, which causes more heat and so on...
the actual 25 amp fuse rarely blows.
beware. if you are melting fuses, you are heating the wires, and the fuseblock, and the fuse very high, and could face a fire if you don't get those bearings fixed. (I.E. change the motor...)
ATF is not a good lubricant for bearings.
clean out the residue, and old grease and get some good bearing grease packed in there.
good luck.

I dealt with this issue last spring.

617 melts fuse 11 in 1985 300SD... what's the scoop?

gregszustak · #13 03-17-2011, 04:20 PM

Thanks, saved me $186

A bit of filing but now I have a working blower.

dude99 · #14 03-17-2011, 04:34 PM

Another place to try for brushes (if anyone cares) are your local mom and pop vacuum repair shops. They usually carry a fairly full range....

moon161 · #15 03-17-2011, 04:44 PM

Starter & alternator shop. Got close and I sanded them to fit. Guy didn't ask for any money and got back to his bench. I left a few bucks on the counter.