Aux Fan Maintenance - PeachParts Mercedes-Benz Forum

rrgrassi · #1 06-07-2010, 12:13 AM

Last week after I had stopped the car for fuel, I went to restart, and there was a loud noise coming from the engine compartment.

At first I though it was the GP relay, then found it was something else...the Aux fan in front of the A/C condensor. After I got home, The fan seemed to work fine, but when I shut the car down and spun the fan by hand, I could hear what sounded like a dry bearing.

Ever heard a fan make noise on your PC? Just amp it up and that is what it sounded like on the car.

I decided to see if I could lube the bearings on this fan. I did take pictures...and so all is well. I took a 2 hour errand to day, and did use the A/C. The fan operated as it should.

Tools used:

8 mm 1/4"drrve socket, extention and wrench

Channel lock pliers

1/4" flat head screwdriver

25/32 1/2" drive socket and impact wrench. Note: I did not have a 20 or 21mm socket...

Tranny fluid

Brake Cleaner

Synthetic wheel bearing grease

What I did:

1. Unplug and remove the fan assembly from the car (8mm socket)

2. Pry off the plastic fan guard (held on in 3 places by a plastic pin molded in the guard.

3. Snip off the wire ties from the motor frame

4. Remove the fan blades (25/32 socket and impact...NOTE: This is a left handed thread, so Righty-Loosey, Lefty-Tighty)

5. Remove the 3 studs and nuts from the fan motor

6. Remove the motor cover (Pry with the small flat head screwdriver in the notches) Do not lose the spacer!!!

7. The motor cover has a ball bearing assembly in it. It is spotwelded in place, but I used brake cleaner and sprayed about a half can through the openings to removed the old grease and the grit.

8. Remove the motor stator (due to the magnets you can either use channel locks to pull straight up.

9. Check the condition of the brushes

10. Clean the bushing/oil impregnated bearing and stator shafts.

11. Put a few drops of tranny fluid in the bushing area.

12. Put a little grease on the stator shafts

13. Pack the ball bearing with grease, and use a little grease on the spacer to act as a seal.

14. Put stator assembly back into motor housing. Make sure is seats fully.

15. Replace motor cover. (test spin by hand. You will feel restistance from the brushes.

16. Reassembly is opposite of disassembly.

rrgrassi · #2 06-07-2010, 12:14 AM

Rest of the pics...

compress ignite · #3 06-07-2010, 12:29 AM

All credit to member "TomJ"
O.E. Fans Do Not Have Sealed Bearings [99.99999% of failure rate]

"The plain bearing in the magnet housing has been good in all (doesn't have to take the torque or side loading that the main fan bearing does.) So I sourced out a supply of SEALED bearings for this application so I can rebuild the fans as they come in."

TomJ TomJ is offline
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Join Date: Sep 2003
Location: BFE, currently CO
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Re: fans
BFE= "Bum F**k Everywhere" ie; will live any old hick place, but no more cities for me (am rural, but near Boulder, CO.)

"Good" price for a new fan is $174. Dealer price is around $300.

You could also do the build yourself rather than spending the shipping $'s if you have a drill, a way to clean everything really well and a pop-rivet gun and rivets. The bearing is a 6001, but DEMAND a sealed (active rubber seal and not just a metal shield - Designation is 2RS for a double radial shield/seal.)

I can help with tips and such, but it's a straight-forward assy and job that about anyone can do. One thing to be carefull of is the dust from the brushes inside can wreak havoc on your lungs, an evac fan and a breathing mask is encouraged while dis-assy and cleaning."
__________________
1984 300D Turbo - 4-speed manual conversion, mid-level resto

1981 240D manual. Bile/Vomit yellow, otherwise known as Maple? Yellow.

1971 220D 4-spd. - Parts running car.

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Last edited by TomJ : 08-15-2004 at 11:06 AM.

tangofox007 · #4 06-07-2010, 01:04 AM

Great info. Looks like I have identified my next project.

MBeige · #5 06-07-2010, 02:49 AM

How can you differentiate just a loud whirring noise from a dry bearing sound?

Does this apply to w124/w201/w126 fans too?

Thanks for the article!

rrgrassi · #6 06-07-2010, 01:23 PM

Quote:

Originally Posted by MBeige

How can you differentiate just a loud whirring noise from a dry bearing sound?

Does this apply to w124/w201/w126 fans too?

Thanks for the article!

Is sounds like a much louder PC fan when it's bearing dry out. IT is hard to explain, but is "moans" or "groans". You can also here it of you spin it by hand.

hey_allen · #7 06-08-2010, 02:40 AM

Looks like another project for my SEC as well. It's fan has been inop for the whole time I've had the car, but I couldn't choke down the price of a new one!

edit:
Well, if the listed bearing is the right part, a vendor on eBay has the SKF part

HERE for about $14 after shipping. (SKF 6001-2RS-JEM)

dantheman67 · #8 06-08-2010, 03:02 AM

It sounds like a scraping sound when you turn the fan. Mine is doing it too.

snookwhaler · #9 06-08-2010, 08:48 AM

Thanks! Good write up. I plan to look into this. Mine makes no noise and spins easily. But, I would rather lube it now than wait for it to fail on a 100 degree day.

There is a 126 Aux. fan in my 123. I wonder if they are the same?

MBeige, I still cannot believe the difference those wheels make on that car. It really does look completely different!

Whiskeydan · #10 06-08-2010, 09:42 AM

Quote:

Originally Posted by snookwhaler

Thanks! Good write up. I plan to look into this. Mine makes no noise and spins easily. But, I would rather lube it now than wait for it to fail on a 100 degree day.

There is a 126 Aux. fan in my 123. I wonder if they are the same?

Both fans use the same motor.

I'd like to see how you mounted the larger W126 fan in the W123.

tangofox007 · #11 06-08-2010, 11:02 AM

Quote:

Originally Posted by hey_allen

Well, if the listed bearing is the right part, a vendor on eBay has the SKF part

HERE for about $14 after shipping. (SKF 6001-2RS-JEM)

SKF is a good bearing, but there is no reason that another brand cannot be used. Just look for 6001 and 2RS on the part number. That is a common bicycle hub and skateboard bearing; your local bike shop might be a good source.

MBeige · #12 06-08-2010, 12:16 PM

Quote:

Originally Posted by snookwhaler

MBeige, I still cannot believe the difference those wheels make on that car. It really does look completely different!

Same here, even I still have to do a double take!

Quick question on the topic: are the bearings all the same for aux fan types? Same through out w123/w201/w124?

fdanielson · #13 06-08-2010, 12:41 PM

After reading a similar thread a year and change ago I bought some sealed bearings off of eBay and went to replace mine as a preventative measure. For the record the fan seems to work OK but draws quite a lot of current and blows the fuse on occasion so I thought a general tuneup may help.

After removing the fan from the car I proceeded to spin the nut on the front counterclockwise (lefty) with an impact wrench until the threads were stripped clean. The odd part is the nut is still holding the fan on but there is no non-destructive way to remove it now. After several moments of poetic reflection I put the fan back on the car and it is running to this day. I keep meaning to scope one out at a wrecking yard but never have gotten around to it.