Fleet Update: A Quieter, Happier Blower Motor

We at TTS have a history of wrenching on our cars. My cohort has schlepped Fiat engines and can probably install European headlights on a Mercedes-Benz W123 in his sleep (assuming the kit was complete). In fact, he’s pretty handy around all manner of Benz products. I’ve built some silly cars in my day, whether it be race-ready BMWs or a Datsun out of Bondo. I still change my own oil, and actually enjoy the Zen-like state one can achieve during a four-wheel brake job.

Fun projects, all of them, in their own ways. But sometimes, you have to lay hands and wrenches on your ride to keep you from stomping a kitten.

It’s cold here in the North Woods. How cold? Real cold. And when the temps drop faster than… something really fast, cars act weird. Creaks and clunks come out of the woodwork. Tires howl and hum. A perfectly aligned car will wander and follow the ruts frozen into the tarmac. Don’t lean on anything plastic or vinyl – like the bolsters on your BMW 3 Series sport seats – because they will crack faster than the aforementioned fast thing.

The heater blower motor in my 1995 Benz E320 starting subtly singing to me last year during the really cold weather, which for Minnesota wasn’t all that cold. An intermittent problem, I could merely turn the fan up to the highest setting to redistribute the bearing lube and be on my way. This year, however, I was not so lucky. Changing the fan speed would change the style, pitch and volume of the noise – ranging from chirp to squeal to full-tilt-boogie howl – but it never went away.

I lasted about a day with this. I was going mental. The commute home from work on Friday was the worst. Anger and pain washed over me. Confusion, too, since you kind of need the heater blower when it’s 28 degrees and raining. Do I turn it off and freeze and/or crash because I can’t see out of the windshield? I can’t hear myself think with all this racket! Only five more miles to go. Three miles. One mile. Where’s my kitten?

One big reason I drive old(er) cars is so I don’t have to pay humans to work on them. One big reason I can work on unfamiliar cars is the Internet. Now, I’ve been on the web long enough to not believe most of what I read and see. However, when I have a Mercedes question, I head to Benzworld.org. The signal-to-noise ratio is outstanding, and for the few repairs I’ve actually had to performs, the guidance and information have been spot-on.

The blower motor bearings can be lubed. You have to take the motor out of the heater box, which looks daunting in pixels but is actually quite accessible. Once you have, you know, removed all the fragile rain tray plastic, the cabin filters, and the entire windshield wiper mechanism. Then it’s just right there.

The first tutorial I found was informative, but would not have helped, as it was for a 1990 model. Turns out, 1994-95 models are specific unto themselves. Luckily, I stumbled across this post from krshultz:

http://www.benzworld.org/forums/w124-e-ce-d-td-class/1633463-diy-blower-motor-bearing-lube-cabin.html

This guy went through the process step-by-step, piece-by-piece, screw-by-screw. I mean, he documented everything. Every. Thing. And it was absolutely correct. What took me about three hours to remove the motor, clean and lube the bearings, clean a bunch of other stuff, and reassemble and test must have taken him all day because of his documentation.

I won’t go into all the details, but if you read through the link above, you’ll get the idea. I cleaned the bearings with generic Brake-Kleen and lubed them with Mobil 1 5W-30 on the end of a Q-Tip.

One gotcha during the process is what oil to use. Apparently, certain oils can create a smell when they get hot. I didn’t have any Redline, as krshultz recommends. However, the Mobil 1 hasn’t made a smell yet. Another gotcha is the age and brittleness of the plastic, especially the fan squirrel cage. I heard trim pieces flex and pop, but nothing apparently broke. I replaced one AWOL screw, but didn’t have the missing clip. And the foam insulation at the back of the engine did, in fact, break. The cage was thankfully unharmed.

So did it work? I think so. Yesterday when I went for my test drive, the fan was gloriously quiet at all speeds when the outside temperature was about 15 degrees. This morning, when it was 3, the fan made just a little tiny bit of noise at lower speeds, which came and went, but only a little.

I can give some slack to just about any part on any car on a 3-degree morning.