W210 Auxiliary fan Poly belt failure OUCH !
 

I had my 98 E320 in a local shop last week for no AC . They recharged it and indicated that there was no obvious leak but noted that my Auxiliary fan wasn't working and I might want to change that .
When I pulled the fan assy I found that the poly belt that connect the two fans had fallen off and got wound up between the fan with the motor and Condenser which was banged up and had coolant leaking from Pinholes on it.If that weren't bad enough apparently it stalled the fan motor that also failed (open).
I've ordered a new condenser and Auxiliary Fan and had several questions I hope someone could answer
1) has anybody seen this before I saw no mention of it in the forums
2) what is the MB PN for the Poly belt I need
3) Do I need to replace the dryer if I change the compressor
4) Is it possible to get the fan detached from the Motor ?
I can get a used Fan on Ebay with bad blades and would take the motor from that but I can't figure out how to detach the blades.

Thanks in Advance
BOb

1: The belt falling off happens. You're not the first, but this is the first I've heard of damage resulting.

2: Check the "Buy Parts" link above. The belt is under "drive belts" on the left-hand pane, then "Fan Drive Belt" on the right. The motor is under "Cooling system" then "Auxiliary Fan Assembly," then the second link, "Motor with Fan." This will replace the active side, and you'll use your old passive side and frame. Don't put a used fan in there, and do not buy a fan assembly from Ebay (I did this, and the fan failed less than nine months later). The new fan motor (with blades and pulley) is $205, and worth every cent. You need that part to work.

3: Absolutely.

4: It is possible to detach it. I know because I've done it. What's probably impossible is putting it back on.

Follow up
 

I found that you can actually get the fan off and I did to understand why the motor failed
Lots of penetrating oil and you can clamp the pulley and twist the fan off
Whan I pulled the fan and pulley off I found why the motor failed .
The motor apparently jammed because the belt was against the condensed and heated up to the point that a solder connecting an internal choke melted and the choke lead sprang out of the connection.
After resldering the choke The motor Ran but I'll replace it anyway because the brushes were shot and I didn't want to deal with ballancing it
BOb

Whenever I have the hood open to check the oil, I turn the exposed part of the left fan and ensure that the right side follows. Call me paranoid.

Can't you just picture the design meeting. "Well here's a way we can save money. Eliminate one aux fan with motor and replace it with a free wheeler driven by a v belt from the other one. Two pulleys, a belt , and a freewheeler will be cheaper than the alternative that has worked well for years and years. I am picturing the design based soley on this thread.

Kind of like buying a 2007 E Class that has no center arm rest, just a breadbox sliding tray cover to rest your right elbow on. Those accountants are simply brilliant marketers.

Steve

In their defense, that one motor is very powerful. Presuming for the moment that the belt failure is rare (it does happen, of course), and noting that you do need both of those fans, one motor has half the chance of failing than two.

Think of a twin-engine airplane that cannot fly on one. Twice the chance of going down.

Failure maybe rare, but it is sitting very close to the Heat Exchanger. Seems to me to be a poor design. If the main motor fails, then you are in trouble, Whereas in previous two motor design, one could fail and you could still get by in most circumstances.

Steve

Oh, of course. I was just playing devil's (bean counter's) advocate.

I replaced mine, no big deal. And I have never heard of a failing belt do that kind of damage.

The elimination of one motor was a weight-saving measure. The engineers are always trying to shave ounces here and there...not as bad as an airplane, but obviously a main concern.

Also, the cost of repair and replacement is probably lower with only one motorized aux. fan.

The bean counters mess up many times...I just don't hink this is one of those tiimes.

we literally have two or three of those a month come through our shop,
some clients decline the repair, but we have never seen any failures cause any kind of damage to any part of the system but to the belt itself

Do you normally just replace the belt?

yes, normally just install new one

wow, you got bad luck. i just see them come off.
no damage so far.
your justified in being upset. i would be.

george

1998 E320 Auxillary Cooling Fan Failure
 

Mine motor appears to have failed. Can someone tell me how to remove from car? I removed the belly pan, assuming removes thru bottom, but lower attachment doesn't want to free up.
I've also noticed that later models don't have fan in front radiator. Is this an upgrade that is worth doing? A/C says system won't work without this fan assy. Is this true? I would think fans are only needed for extra cooling & not part of the whole A/C system

"Extra cooling" includes running the AC. That produces extra heat.

If your fan is in front of the radiator, remove the guard, the clips that hold the radiator to the core-support top cross-member, the top cross-member itself (unclip the cable for the hood release underneath), the horn and hood bumper and the bracket that holds them to the front bumper frame, and undo the three bolts holding the power-steering cooling line so it can be pushed out of the way (this line need not be disconnected). Next undo the electrical cable connection and the two bolts at the top of the fan assembly, and it lifts out easily enough.