'92 300SE

Noticed a peculiar noise this AM when pulling into the garage @ work. Either the bearings/bushings are gone, or there's something wedged in at the rim of the driver's side aux fan. Fan still turns when powered by 12v, but makes a considerable racket. Turn car off, fan turns rough by hand - doesn't free-wheel at all like the passenger side fan.

I've pulled the power to the driver's side fan until I can determine what's the cause of the noise.

I'm assuming this will just result in higher engine temps if I get stuck in traffic, plus a little reduction in A/C performance.

Any other items I should worry about?

Thanks

I don't think there's much to worry about. I drove for quite a while with one fan out. Just watch temps when stopped, etc. If temp gets too high you can always dump some heat by turning on the heat to max.

The fan motors get gunked up with bugs and debris, although you wouldn't think they would, the way they are facing. I think all our cars of this vintage are starting to experience failing fans.

I replaced the failed one on my car and I've tried to clean out the failed one. I've reassembled but not tested it yet. You have to bend the motor can tabs to take out the guts, which is a PITA, and it's ugly when reassembled.

Rgds,
Chris W.
'95 E300D, 240K

Fortunately, yesterday afternoon was reasonably cool, for Houston in August, at any rate.

Stopped by MB and picked up a new fan motor.

I only ran the A/C while I was moving on the freeway - didn't notice any adverse effects.

Got home, checked AllDataDIY and was sad to learn that you have to remove the fans as AN ASSEMBLY WITH THE CONDENSER!!!

I figured someone's smoking crack - surely they're kidding, right?

Almost - the high pressure port sticks through the shroud assembly facing forward, making it virtually impossible to remove the fan assembly. Also, part of the shroud wraps around the lower pressure hose leading (I assume) from the condenser. I managed to free it without breaking anything, but it took some doing.

Once I got it out, I discovered that the fan spins freely. I checked it before I started the work and it was definitely binding - which I assumed was failed bushings/bearings.

Gave it a spin and a listen - no noisy bearings - at least it sounded just like it's partner. Hand spin both, they both stop about the same time.

Took the opportunity to clean the condenser of miscellaneous leaves, bug carcasses (carci?) and general road gunk before reinstalling fan.

All is well again.

I don't mean to hijack the thread, but how hard a job ws it to replace the fan? The FSM also had the radiator and condensor coming out which would mean an AC recharge. Were you able to replace the fan without breaching the AC?


Thanks!

__________________
Tim Benner

00 ML320 170K
95 E320 wgn 160K

My car's a 140 chassis, if you're referring to your E320, I don't know for sure.

For a 300SE, the effort was not without some breakage, most notably a small crack in the shroud on the driver's side. This was as a result of trying to pull the shroud far enough forward to clear the high-pressure port. The crack isn't noticeable and won't effect performance. If I had fully disconnected the shroud at the two rivets and pushed back on the radiator first, I probably wouldn't have cracked the shroud.

Remove the grill that covers the fans. There are two plastic rivets at the top and two at the bottom. Be patient with these fellows - they're brittle and break easily.

Remove the upper radiator support - three bolts at the left and right near the hood latches, and one in the front center between the fans above the resistor pack.

Removed the 8 bolts that attach the shroud to the condenser. Three are straight across the top, two are on the left and are visible inside the arc of the fan blades. Two are on the right in the same position. One is in the center at the top behind a cap of about 1" diameter. There are two other bolts visible in the middle between the two fans (one from the left, and the other from the right side) - these hold the fans together and to the bracket that attaches to the center of the condenser - do not remove these.

I also removed two plastic rivets in the center just below the previously mentioned bolt. This will allow better flexibility for the shroud to clear the high-pressure port.

Disconnected the wiring to the fan resistors, and the leads to the fans themselves at the corners of the shroud. There are 4 retaining clips for the wires - patience will get these out without breaking them. Dismount the cable from the 3 zip-ties that hold it down to the bumper frame and work it out and around the bracket on the driver's side of the bumper. In hindsight, it would have been easier to disconnect the fan leads and their clips, and remove the resistor set as a unit without disconnecting the wires.

I also disconnected the power steering cooling tube at it's 3 attachment points. Care should be exercised here - I thought the attachment bushings needed to be separated to remove the tube - and I broke all 3 into small pieces. (Replacements are readily available at MB for about $10 for the set of 6 pieces). Even the protective grille is a cheap replacement. List is $9.25!!!. The fans are another story - $210 list, each.

Remove the driver's side tow hook cover. Reach in and feel where the shroud comes down and covers the bottom of the condenser. Move the shroud forward and backward and you should be able to feel where there's a notch in the side that wraps around the lower tube leading to (or coming from) the condenser. That notch will catch on the lower tube and prevent you from lifting the shroud out.

Push back on the radiator towards the motor - this will move the condenser, too - so don't get too aggressive. On my car, there's plenty of room between the engine-driven fan and the radiator. V8/V12 cars probably don't have as much room. Most likely the V12 isn't serviceable in this manner. V8 cars should probably have the fan removed before attempting this service.

Pull forward on the shroud until you've got clearance for the high pressure port to pass behind the shroud. Reach down and slightly rotate the edge of the shroud to allow it to clear the lower tube on the condenser and wiggle/jiggle the fan shroud until you can pull it loose.

Reinstallation is the reverse of installation - you'll have to bend/rotate the lower edge to get it back in place like you did to remove it.

Be patient and gentle and the process is doable with a minimum of fuss.

Total job - start to finish, was less than 1 hour.

That is a great writeup! Thanks for that. I also have one fan out. They're about $150 here for the E320 so not too bad on price but I'm not ready to start into the AC.

__________________
Tim Benner

00 ML320 170K
95 E320 wgn 160K

Check this link:

http://www.peachparts.com/shopforum/showthread.php?t=129075&highlight=aux+fan+removal

Thanks J M. That fan runs if it just touch it... too bad it won't just heal itself. That would be even easier.

__________________
Tim Benner

00 ML320 170K
95 E320 wgn 160K

Does the non working fan spin freely by hand? Is it the same as the working one? If it has more drag then your problems are likely mechanical. If it is free like the working one your problems are more likely electrical.

Electrical connections near both motors should be looked at. and at the source connections at the dropping resistors on the fender well behind the drivers side headlight. These get very hot and are prone to corrosion because of the heat of the dropping resistor. Check and tighten the bolts on that, perhaps removing and clean it.

If all is well with both electrical and mechanical , when you fast spin one fan by hand it should rotate the other one slowly because the spun fan creates some current that passes into the second fan. If it does not, you know it either has some mechanical drag or perhaps and electrical disconnect. OR perhaps a worn out motor?

I was thinking that there was an electrical problem. I'll check the resistors on the fender well tonight and try and get to the fans this weekend. Given that the left fan comes on when touched the problem is likely in the wiring or motor itself. Or maybe worn out brushes or dead spot on the commutator assuming it is not a brushless motor?

Thanks,

__________________
Tim Benner

00 ML320 170K
95 E320 wgn 160K