The races, from what I recall, were in fact slippery. They looked like they offered a "lip" to catch, but the problem is that the lip is just part of the rounded race. However, although the screwdriver would keep slipping off when I pounded it, I kept at it, and somehow after about a half hour of seemingly useless pounding, it came out. I still don't know how it came out.

__________________
08 W251 R350
97 W210 E320
91 W124 300E
86 W126 560SEL
85 W126 380SE Silver
85 W126 380SE Cranberry
79 W123 250
78 W123 280E
75 W114 280

Thanks. That is exactly what I plan to do tomorrow. It seems to be quite stuck in place.

I plan to will use a Dremel cutting disc to try and cut a flat ledge for the screwdriver. That might help things a bit.

__________________
2008 E350 4matic / Black/Anthracite

------------------------------------
Gone but not Forgotten:
2001 E430 4matic, 206,xxx miles, Black/Charcoal
1995 E320, 252,xxx miles, Black/Grey
1989 260E, 223,00 miles, Black/Black

Success!

After my last post, I sprayed around the race with WD40 and left it alone. This morning, after less than 20 taps with a hammer and screwdriver, it came right out.

__________________
2008 E350 4matic / Black/Anthracite

------------------------------------
Gone but not Forgotten:
2001 E430 4matic, 206,xxx miles, Black/Charcoal
1995 E320, 252,xxx miles, Black/Grey
1989 260E, 223,00 miles, Black/Black

This repair when well. Should anyone be interested, here is what is involved.

Tools

• 16mm Socket (to loosen/tighten belt tensioner)
• 13mm Socket (loosen/tighten pump bolts)
• 1.25” Socket or other Drift to push bearing out of pulley
• Rubber Mallet (to hammer out bearing)
• Screwdriver, Carpenters Hammer and WD40 (In case bearing has disintegrated).
• Brake Parts Cleaner
• Retaining Ring Pliers to remove retainer ring on pump shaft
• Electrical Tape (to repair inevitable damage to pump wire insulation.

Parts
Double Row Radial Ball Bearing, Both Sides Rubber Sealed.
ID:32 mm x OD:52 mm x W: od 18 mm + id 20 mm

BearingsDirect.com
Part# 32BG05S18G-2DS
$18.99 + shipping

Note: These are the same parts sold on eBay, without the 100%+ markup. One seller uses the exact descriptive language that BearingsDirect does.

Remove Pump From Car

Remove Air Filter Housing

1. Remove filter cover and Filter.
   
   
2. Lift out the cover in front of the air filter housing, and directly behind the passenger headlight.
   
   
3. Remove the nut on the top rear left of the air filter housing, attached to the wiper fluid reservoir. It holds a rubber wedge that keeps the air filter housing in place.
   
   
4. Remove the housing by pulling up from the rear, then front. It is held in place by two plastic nipples on its bottom, which insert into two rubber “Doohickies” (Don’t know the correct term.)

Remove Fan Shroud

1. Pull out plastic clip on top of the circular ring part of the shroud, and tilt it against the fan blade to make room for the main shroud to be removed.
   
   
2. Slide off the two metal clips securing main shroud: one plainly visible on the left of the shroud, and the other on the right of the shroud, abut about an inch or two lower. Lift this shroud up and out, and then the circular ring.

Loosen Serpentine Belt

• Rotate the tensioning pulley clockwise with an 16mm socket to release tension on belt. (Note: My car is late 95 E320. Your vehicle may differ.)

Remove Air Pump

1. Remove electrical connector to the pump. On the 95E320, it is behind the black protective cover at the front of the engine. Just trace the wire from the pump. There is a cylindrical rubber “bumper” (don’t know term) that you must slide off its post in order to move the connector from its nook. There are actually two of these. Remove the upper one.
   
   
2. Remove molded rubber hose from the rear of the pump. It uses a spring-type clamp that must be compressed. It twists off easily with pliers, but is a challenge to get back on unless you have the right tool for it (which I did NOT).
   
   
3. Remove the coolant tube that runs along the left side (facing forward) of the pump. Just detach it where it connects below the overflow coolant tank & washer fluid reservoirs.
   
   
4. Remove the upper Pump bolt, which is long. Then the lower bolt, which is short. If you have one of those skinny sockets, use it, as you will be working between the fan blades, and a thinner socket will be a bit easier. You will also need an adapter/extension to get at the lower bolt, if you leave the fan attached for this job.

Step Two: Replace Failed Bearing

Remove & Replace Pulley/Bearing

1. Remove front nut.
   This was a challenge. I had do use a C-Clamp to lock the clutch in place. Once off, the clutch lifts right out.
   
   
2. Remove locking ring holding the pulley in place.
   
   
3. Slide bearing and pulley from shaft.
   
   
4. Use 1.25” drift to hammer old bearing out.
   
   NOTE: If the bearing has disintegrated, and the inner race and ball bearings have fallen out (or have been removed) the outer ring will be stuck in place. Turn pulley front-side down, soak the edges of the outer ring (of the stuck bearing) with WD40, and find something else to do for a few hours.
   
   When you return, use a screwdriver and carpenters hammer to strike, obliquely, at the outer race. Tap a few times, then rotate the pulley 30 degrees or so. If your experience was like mine, you will not complete a 360 degree rotation before the outer race is dislodged. This will be easier if you use a Dremel tool and cutting discs to grind away those six tiny retaining tabs that somewhat helped hold the original bearing in place.
   
   
5. Clean the pulley and place in oven at 400 degrees. Put new bearing in freezer. (Credit to MercedesShop member Brewtoo for this). After 30 minutes or so, remove pulley and bearing and slide bearing into place.
   
   Note: I prepped the pulley surface by lightly sanding with the Dremel and sanding drum. I also sprayed a spot of WD40 on my finger and rubbed it around the periphery of the bearing when I removed it from the freezer. The bearing slid smoothly into place, after which I shock-cooled the pulley under the kitchen sink tap. Bearing was solidly in place.
   
   
6. Slide Pulley/bearing onto shaft.
   
   
7. Replace locking ring.
   
   
8. Replace air pump in car.

__________________
2008 E350 4matic / Black/Anthracite

------------------------------------
Gone but not Forgotten:
2001 E430 4matic, 206,xxx miles, Black/Charcoal
1995 E320, 252,xxx miles, Black/Grey
1989 260E, 223,00 miles, Black/Black

Very nice, Eric.

__________________
2012 E350
2006 Callaway SC560

Thanks.

In hindsight, one thing I would do differently is to make loosening the clutch nut Step #1, while the pump is still on the car with the serpentine belt on.

Loosening that nut is not easy on a rotating pulley. With the pump on the car, and the belt still tensioned, the pulley will not budge, and a few nudges with a socket, and long extension handle, are all that would be required to loosen it.

Also, I believe I am missing some sort of ring between the clutch and the pulley. I hear a soft scraping sound - - the same as I heard after reattaching the clutch and spinning it -- and am wagering that some sort of non-metallic ring belongs between the clutch and pulley to silence that noise. Is that correct?

__________________
2008 E350 4matic / Black/Anthracite

------------------------------------
Gone but not Forgotten:
2001 E430 4matic, 206,xxx miles, Black/Charcoal
1995 E320, 252,xxx miles, Black/Grey
1989 260E, 223,00 miles, Black/Black

This is an older thread but I am getting ready to go through this process today and am wondering if anyone has a response to the inner ring (grinding) question??? I have a new bearing on hand. I haven't taken apart yet but I found a light wieght metal ring under the motor when this failed laying on the plastic under cover. It looks like a piece of a race or some kind of light metal piece that I am worried I am going to need. Any pics of a newly install pulley bearing ready to reassemble to the pump or help would be appreciated.

Funny you should ask -- because the grinding/scraping only recently stopped, after about 3 years.

There is no inner ring. The clutch was bent in a way that caused it to rub against the pulley. Remove it before the pump is off the car and you will have no issues.

__________________
2008 E350 4matic / Black/Anthracite

------------------------------------
Gone but not Forgotten:
2001 E430 4matic, 206,xxx miles, Black/Charcoal
1995 E320, 252,xxx miles, Black/Grey
1989 260E, 223,00 miles, Black/Black

Thanks. I have done the repair. I am just waiting on a new idler pulley as the old one looked rough and since I have the belt off and shroud etc out of the way I figured I may as well replace that. The most difficult part of this whole endeavor was getting the old belt off. I thought I'd need to pull the fan off, but couldn't get it loose. I understand the pulley holding tool I think but couldn't jerry rig anything to work. I also had zero luck holding the pulley with the old belt. Maybe I could have if I would have tried when the belt was still fully on but i didn't plan to remove the fan at that point. Finally after a fair amount of cussing, I was able to work the old belt out from between the fan pulley and the harmonic balancer crank pulley. Funny enough, the new one popped right in there. Great info, had no problems replacing the bearing. That part went smoothly. My magnet looks rough, I don't know if this thing will actually still work or not and honestly I don't really care as I just need the pulley to hold the belt. There is no emissions test on this car anymore as it is a 95 and that's too old for NC testing. I should be good to go once I get the idler replaced.

This must be a stupid question but why is it you have to take the pump off the car? Why not just take the pulley off the pump? On the car I mean.

That would have been a great question... three years ago. At the time, all the instructions I read in these threads required removal of the pump.

In hindsight it would be easier to leave it on the car -- IF -- you can remove the locking ring holding the pulley in place without losing it. Getting at it with the pump on the car, using those locking ring pliers, might be a challenge. (And if it flies away, and you don't have a replacement, things will be bad.)

__________________
2008 E350 4matic / Black/Anthracite

------------------------------------
Gone but not Forgotten:
2001 E430 4matic, 206,xxx miles, Black/Charcoal
1995 E320, 252,xxx miles, Black/Grey
1989 260E, 223,00 miles, Black/Black

Yep, I agree with Eric, it could be done on the car I think. However, taking the pump off is actually trivial and then you can clean up things better on the work bench. Pulling the air box is 30 seconds, then it's only 1 wire plug, 2 bolts and a short hose and the pump is in your hand. My bearing had failed (disintegrated actually is a better term) so I wanted to inspect things closer and clean up the shaft etc. Eitherway would be fine though. Putting it back on was literally less than a 5 min job. I would estimate 10-15 minutes total for the actual pump removal and re-installation so it's not worth fretting about if you have any reservations about how difficult of a repair it is.