E420 Auxiliary Fan R&R
 

Hi All - I think the aux fan in my 97 E420 is going. I hear a "rattling" like noise when it is operating. I removed the aux fan grill and spunit by hand and heard the noise as well and saw no foriegn object impacting the blades.
I see that I can either replace the dual set-up for about 250.00 or the fan/motor for about 200.00.

My question is has anyone replaced this OEM set-up with an aftermarket? It would seem to me to likely result in significant cost savings w/o sacrificing quality/longetivity? Assuming of course I could find a suitable aftermarket product that would fit. Any unique electrical requirements that you may think I should consider?

Would anyone have some thoughts on the matter? Or better yet, have the expereince of doing this mod? In any case, would anyone be able to confirm I can access the aux fan unit from the from of the car simply by unbolting the metal cross member?

Thanks for any input.

I tried an aftermarket assembly and used it for about nine months. That's when it quit starting all of the time. Bad move.

You can buy just the left side, with the motor, blade and pulley. You should also get a new belt if you do this.

The fan is easy to change. You have to remove the cross member, and also unbolt the power steering pipe from the car body (the lines can stay attached).

you can probably clean the bearing on the fan (I did on the 190e) leaves, dirt, dead insects all collect in the bearing. I cleaned it with brake cleaner then greased it with axle grease. I took the fan motor completely apart, was actually pretty easy. Now the fan spins freely and quietly. my 2¢

Thanks for the tip! I'm going to try your fix tomorrow. I'll let you know how it works out. Your 2 cents may very well save me 2 hundred! Thanks again -:)

I too had one that was full of bugs and leaves that got in from the back side. Cleaned them out and it was fine.

I tried to dismantle my fan, and was completely unable to get it apart without destroying the motor. You may have better luck, but I doubt it.

This fan is too important to screw around with. Do it right the first time and prevent more expensive problems down the road.

Thanks Matt. I'm thinking I'll be able to dismantle the fan to the point where I can discern if going further is or isn't a good idea. Taking it out of the car will be no risk. If for any reason, I'm curious if the "rattle" noise is simply the result of foreign debri - in which case I'll clean and lubricate, put back into place. Still noisy, I'll purchase a new one.

If you do need a new one, purchasing the "fan motor" online is cheaper than an aftermarket (and junk, IMO) assembly. Your right-side fan is probably fine. Be sure to order a new belt.

I didn't specifically address this earlier, but there are specific electrical requirements for this motor. It's not run by resistors and relays as the prior fans were. The fan motor is pulsed to start, and to run at less than full speed. If the controller sees the wrong electrical signature from the fan, it shuts down the power and tries again in a few seconds. Well, mine does. Yours works similarly, but using different modules.

I did not have to dismantle my fan to get the junk out of it. I simply removed it, vacuumed the crap out of the openings in the back and reinstalled it.

I was able to get one for 80 dollars shipped for my 124 260e.

There didn't seem to be a way to get to the bearings.....

i sprayed some lubricant in there from the front holding nut and it bought me some time.... but it is summer and i need reliable a/c.... i had visions of blowing up my compressor....

mine was also drawing too much current at high speed..and blowing a fuse... i suspect the bad bearings were overworking the fan, causing that issue..

It's usually worn bearings causing the noise.

If it keeps throwing the cheap rubber band belt, I'd replace the fan motor with an M/B part.

Aux Fan Fixed
 

I removed the aux fan on my 97 e420 using MattLs step-by-step instructions (thanks Matt!). The belt was inverted and found to be the source of the noise. I replaced with a new belt, lubricated where opportunity allowed (minimal) and reinstalled. I took the opportunity to also clean the condensor and surrounding areas. Fan works like new - nice and quiet. I wonder how the belt finds intself "flipping" over time?

Thanks for all who offered me a reply. Each and everyone was a help.

Good news. If I were to guess, I'd say either wear or foreign debris caused the belt to flip.

Any time I have my hood open, I turn the exposed part of the left fan blade by hand to ensure that it turns smoothly and that the right side turns as well. I know I'm a bit paranoid, but it's just so easy to do.