NOTE: I've updated this first post to include the discussions and experience/feedback that was given by kind people below as well as my own experience. The job was not bad (although definitely not a breeze), most of my time was taken by being unsure of what to do and how to do it since I didn't have a manual .... therefore if you're going to try this repair yourself (recomended) follow the steps immediately below :


I've perused this topic via various thread and have come across a bit of conflicting information. This is what I have found for anyone tempted to do this job themselfes. I don't think it is that difficult at all. I took my time over about a week of evenings (and a case of beer )


- no need to remove radiator at all, period.

- no need to remove fan, clutch etc as some suggest, period.

- in fact, no need to actually 'remove' anything except pulleys and air cleaner

- remove the airfilter housing (2 screws and losen the vertical one on the side and remove the complete housing to give more working room.

- the fan shroud needs to be losened by removing the two clips only, leave the shroud in place, removing the clips allow you to move the shroud over a tad so that ......

- ... you can losen the 19mm tensioner bolt just below the long adjusting nut

- losen the long tensioner bolt to slacken the belt

- remove ps pump and w pump pulleys (get a strap wrench)

- remove the 19 mm bolt

- unbolt the hex bolt fastening the dipstick to engine so that the dipstick can be moved a little to get better access to the 2 rear 13mm bolts hoding the waterpump (again, not critical but easy to do and helps to get access)

- losen the heater pipe allen underneath the distributor and pull on the pipe to seperate from pump (replace washer)

- undo all the bolts holding the ps pump and the tension/idler assembly

- now you can start undoing the w pump (you will need extensions, universal and some tape to hold the universal straight, I did everything using 3/8"). Start by removing the front 6mm Allen bolt with an allen tool and a bit of pipe to get more leverage.

- the lower rear 13mm bolt comes out easy with a 3/8 drive and extension

- the upper rear 13mm bolt I found a lot trickier because of not very much room, but finally found that a combination of the smaller 1/4" drive to the bolt and then a 3/8" extension did the trick perfectly.

- finally the lower front which is not bad to get at once you move the tensioner assembly out of the way. (note, I did 'not' remove any bolts from the engine itself (there is one into an oil passage to do with a casing that holds the tensioner), just enabled myself to move the round tensioner assembly an inch or so as well the ps pump is just pushed out of the way)

- you are done. I did not use any grease with the o-ring as per dealer recomendation... it stays on well enough and wiggling tells you pretty quickly if it is sitting properly.

- replace the 2" heater hose (even if it looks good, you won't get at it again)

- reassemble everything in more or less reverse order. I did not worry about torquing in some kind of systematic way when mounting the w pump .... I mean, after all, it's heavy duty cast. I doubt it would make a difference like it does,eg, on a wheel. the little pointer on the tensioner came off - no big deal, it simply fits on losely and ratches (ie move it along with your finger) into position.

- put the belt back on, tightened and filled with water ... tiny, tiny leak on the thermostat seal because I tried to reuse the old washer.... put in new washer - perfect. I tried to save new washer because I plan to exchange the plastic housing for a metal one.

- cheers, guenter

ps after you r&r the w pump ... should other items in this vicinity ever need replacement in future ..... it will be a breeze.

Unbolt the power steering pump and move it to the side.

__________________
Regards

Warren

Currently 1965 220Sb, 2002 FORD Crown Vic Police Interceptor

Had 1965 220SEb, 1967 230S, 280SE 4.5, 300SE (W126), 420SEL

ENTER > = (HP RPN)

Not part of the in-crowd since 1952.

I replaced the water pump in my '88 260e so it is fresh in my mind and this info may help:

- no need to remove radiator at all, period.
True


- the fan shroud needs to be losened by removing the two clips only, leave the shroud in place, removing the clips allow you to move the shroud over a tad so that ...
If you have a one-piece fan shoud you need to loosen the clips and move the fan shroud to access the 8mm allen socket in the center of the fan clutch. There is a special tool that can be made to hold the fan pully while you loosen the bolt. It is usually pretty tight. You need to remove the fan clutch, fan shroud, and fan pulley.

- you can losen the 14mm tensioner bolt just below the long adjusting nut
First you need to loosen the 19mm nut on the front of the tensioner 2 turns. Then loosen the 13mm adjusting rod at the top of the tensioner CCW until the rod is flush with the top of the nut. This should allow you to remove the serp. belt. You may have to pull on the belt to compress the shock before the belt will slip off.


- remove the airfilter housing (2 screws and losen the vertical one on the side to give more working room (not critical but easy to do and less frustration)
Definitely remove the air filter housing. There are 4 - 10mm screws on top that need to come off also.

- unbolt the dipstick fastner near the top so that the dipstick can be moved a little to get better access to the 2 rear 13mm bolts hoding the waterpump (again, not critical but easy to do and helps to get access)
The dipstick fastener is easy to remove and will allow access to the upper rear bolt on the water pump. I was able to loosen the bolt with a 13mm box wrench and a 13mm open end wrench from above. A 12 point wrench requires 30 degrees of movement to get a second bite and there is not 30 degrees of clearance. That is why you might need a couple different wrenches with various offsets. I used a 3/8" u-joint to remove the bolt after loosening it from above.


- remove the front 6mm Allen bolt with an allen tool and a bit of pipe to get more leverage.
That is exactly how I did it.

- the lower rear 13mm bolt comes out easy with a 3/8 drive and extension
I used a 13mm socket with a 12" "jiggle" extension that bends slightly but is more stable than a u-joint. It worked real well for me on this bolt.

- the upper rear 13mm bolt I found a lot trickier because of not very much room, but finally found that a combination of the smaller 1/4" drive to the bolt and then a 3/8" extension did the trick perfectly.
The upper rear is the most difficult but by working from above and behind you can get it.

- Now, my big question ..... how the hell do I get at the front lower bolt do I need to remove the tensioner mechanism and the cylindrical reservoir next to it (dont know what it is ... maybe power steering?) Please say I don't need to do this ... is this where the dealership earns their 5 hrs charge
The lower front bolt is easily accessible with a 13mm wrench after the tensioner is removed. The tensioner has to be removed to physically remove the water pump from under the manifold. The two PS pump bolts attached to the tensioner mounting plate also need to be removed to allow the pump to come out. I tried getting the pump out without moving the PS pump and could not do it. Removing the PS bolts is not difficult though.

One thing not mentioned is that the fan, PS pump, and Water pump pulleys all need to be removed in order to remove the tensioner. I sprayed PB blaster on the bolts and shafts first to loosen them up. To keep the pulley from turning while loosening the bolts, I used an old serp belt wrapped around the pulley and under the crankshaft and looped over the alternator pulley. The pulleys are usually tight on the shafts. Mark thier positions relative to the shaft and be carful not to distort them when removing. I tapped them off using a long screwdriver and hammer. Tap them as close to the hub as possible. The left bolt on the tensioner needs a dab of RTV sealant when replacing because it is treaded into an oil passage.

It's not a difficult job if you have patience and allow yourself plenty of time. I have found that working on a Mercedes is 90% mental and 10% hands-on. It sounds like you are already sorting through the mental part.

John, terrific post, I found it interesting and I don't even have the car.

I did it pretty much as John described. I have seen it written that by using the FLXM13 SnapOn tool the pump can be removed without removing the p/s pump or tensioner, but I sure don't see how. I just pulled the tensioner and the p/s pump, moving it aside and went for it.

Good luck,

Many thanks, great post John. However, I wonder if there are some differences between my '89 300E and your '88 260E in terms of how components are mounted.... the slight differences in the model years is probably how my confusion arises

and, by the way, can the themostat just be 'yanked' out? or does it need to screw/twist or unbolt in some way? I guess it is just in really tight because of old age

many thanks again for this detailed advice ... I'm sure it'll help many in a similar situation guenter

Larry, thanks for your input. Let me please ask, did you also need to remove, as John describes, the fan and pulleys on PS and tensioner to get at the water pump? Did you have a 300E?

best regards, guenter

Warren, thanks for your present and also your previous suggestions re the water pump removal (I note that you also have a 103 engine of the same year and so avoids possible differences in engine layout. I've removed the top front and rear top 13mm bolts but can't move the PS pump. Are there more mounting bolts beside the two I mentioned that I'm not seeing??
You are then saying, if I understand correctly, all I need to do is to remove the PS pump and move it sideways, and I can leave the Tensioner mechanism in place and work 'around' this tensioner mechanism to get the water pump out??

cheers, guenter

[QUOTE=Guenter] and, by the way, can the themostat just be 'yanked' out? or does it need to screw/twist or unbolt in some way? I guess it is just in really tight because of old age

Once you've unbolted the three 10mm bolts, the thermostat housing just lifts straight off. You may need to lever it a bit to unseat it from the rubber gasket though.

Dig out the black o-ring with a small pick (this is the important part), then the thermostat will come right out.

[QUOTE=anthonyb]Anthony, just like you said. I took a dental pick and ran it around the outside of the rubber o-ring .... and the thermostat popped right out.

cheers, guenter

I removed the fan disconnecting the outer most bolts to take the fan off the clutch, leaving the clutch in place. I did not remove any pulleys. As they have said the P/S pump has to be unbolted and moved some to get the pump. At least that's what I had to do.

Yes I have a 300E. The 260E is the same and all 300E's with a 103 engine.

Good luck,

All right, thanks. I found the third bolt on the bottom front left of the pump. Actually, what I did was to losen the 'nut' on the rear which allows the ps pump to swing sideways out of the way. I can see the bottom left bolt now on the water pump ..... sure can't fit a socket inbetween the tensioner box and the water pump.... I guess the tensioner box needs to be losend after all. Can anyone comment ??? Am I missing something simple?

I plan to write up the 'complete' instructions for the pump R&R for future marginal wrenchers like myself who plan a water pump replacement

This is an opportune time to check and replace some components...

Make sure you check the condition of the belt tensioner...The damper is probably just fine. If you replace the tensioner, I've heard it said that the tensioner adjustor rod should be replaced too, but that is probably becuase unknowing owners cranked on the adjustor without first loosening the 19 mm bolt on the tensioner.

Carefully inspect the serp belt. If in doubt, throw it out. How old are your radiator hoses? Inspect those too.

If you have the original radiator, be aware that they are prone to cracking at the neck on the plastic tanks on the sides. For that matter, if you have a plastic thermostat housing, plan on replacing that! (I had one crack on me.) The part has been updated to a cast metal part.

What is the condition of your fan clutch? Does the fan spin easily? If so, search on fan cluch refilling. I refilled mine with Toyota silicon oil and brought it back to life. Check the condition of the ilder pulley. Easily replaced if it has bad bearings.

A $12 strap wrench makes easy work of removing the PS pump pulley and Water Pump pulley, both necessary for this job. Also, if you don't have the tool to lock the fan clutch in place to remove that allan bolt on the front, you can remove the serp belt, remove the idler pulley, the cover over the distributor, and put a strap wrench on the fan pulley to hold it while removing the allan bolt.

But also check the bearings on the fan clutch bearing bracket on the motor. If that bearing feels rough at all, you can remove the bracket from the motor (pay close attention to the location of the mounting bolts, especially the tapered one that has an oil seal on it.) You can then carefully pry off the bearings seal and inspect the grease in it. 10 to 1 that the grease has started to dry up. It takes time, but you can squeeze more grease in there from the open side (the other side faces the inside of the bearing bracket, and the bearing is pressed in and not easily removed), then carefully replace the bearing seal, which should help make that $150 dollar part last a bit longer...

By far the hardest part of this job is that one evil bolt on the water pump.

__________________
On the plains of hesitation bleach the bones of countless millions who at the dawn of victory, sat down to wait, and waiting -- died

Looks like you have it all pretty well covered.
Just wanted to note after the first two or three of these I started to suction out the p/s fluid, remove the p/s fluid return hose, then the p/s fluid resavour. That allows you to just remove the nesassary p/s pump bolts and just pivot it out of the way and have lots of room to get the bolt w/pump bolts back in too.

Hope you get it back on the road soon.

.... snip.... thanks,will do, excelent suggestion

.... great suggestion, thanks, baught one last night and the pulleys came of with essentially no effort.... great tool to have!

.... great, I thought the bolt on the upper rear of the water pump was bad enough

many thanks, guenter