Coolant Pump - 103 Engine - "how tough is it?"
 

I have the shop manual, and the listed tasks...

It seems straight forward, but is it?

Seems like the manual suggest taking several steps, remove some bolts, and replace - is that all there is? I'm considering if I should do the job, or hire it out?

Per the Mercedes shop manual...
Coolant at engine and radiator ..............drain, pour in (20-010).
Air scoop ...................................remove, install (step 4).
Viscous fan clutch ..........................remove, install (20-312).
Poly V-belt .................................remove, install (13-342).
Belt pulleys of fan clutch and coolant pump .remove, install.
Engine compartment covering below ...........remove, install (step 9).
If air conditioning fitted ...................unscrew, screw on refrigerant compressor with
.............................................pipe group from engine (step 10).
Support with tandem pump & connected lines .. unscrew, screw on (step 11).
Thermostat (252) with new seal (251) ........remove, install.
Belt tensioning bracket .....................slacken, remove.
Return line .................................unscrew, screw on (step 12).
Coolant hoses (266) and oil line ............detach, attach (step 14).
Coolant pump ................................remove, install (step 15).

Commercial tools
liexagon socket wrench with 6 mm, 3/8" joint
7 mm hexagon socket wrench on flexible shaft for hose clip with screw drive e. g. liazet

;)

Thanks

Take right at six hours, and the bolts on the water pump are a PITA (no problem if the PS pump wasn't in the way...).

You must also check the fan clutch and the belt tensioner before you start the job, as both really need to be replaced if bad -- I would just buy the tensioner, unless it's been replaced in the last 10,000 miles it's shot more than likely.

The factory water pumps last forever on these cars, typically well over 100,000 miles (some go 200,000).

Not a bad job, just a bit fiddly.

Peter

Took me 5 to 6 hours, and I took my time. Not a bad job, just kills your lower back from all the bending...

Not a bad job. I would agree with previous replies...about 5 hours. Most of that is prep and nugging your way through the de-install. I didn't take my fan clutch out nor did I drain my entire cooling system. I bled it a bit and that brough tthe fluid level well below the pump / block entry point.

Be very patient! Take your time. It's just a big puzzle. You will have to get the vbelt, power steering pully and pump out of your way as well as the belt tensioner. I didn't completly remove any of these parts.

Make sure you have a flex shaft extension for your sockets or a few socket joints. Some of the angles are pretty tough. Have a several different lengths of socket extensions handy too. Somtimes a 12" is too long and a 3" isn't long enough. Also, your hex or allen wrenches...you may have a need for one that is very stubby. (Rather than the typical that has a 3 to 4" shaft a 90 degree turn then a 1" shaft after the bend, itis very handy to have one that is less tha 1/2" after the bend. I recall a few close quarters.

If you have the time, the water pump is pretty doable. If you have all 13mm bolts on your water pump, the Snap-On FLXM13 wobble extension will be a god send for getting at some of the harder-to-reach bolts.

And don't forget to replace the short bypass hose between the head and the pump.

Anthony

In addition, use some grease to hold the O-ring to the pump body otherwise it will fall out and you'll make a mess all over the place. Then you will be really PO'd.

Thanks for the replies
 

I'll buy the parts and spend the weekend "under the hood'.

The tools are a great idea - and my neighbor happends to sell Snap-on tools.

Your neighbor probably won't have an FLXM13 on the truck, but it will be worth the wait. It has a 1/4" shaft so you can get it on the top bolts. That small shaft, however, will make you think that you are going to break it in half when it rotates before breaking the bolt loose.

I have heard of people changing the water pump using one of these tools WITHOUT removing the p/s pump and all that stuff, but I would have to see them do it to totally believe it. A very reputable pro tech that used to post on this site frequently said that he could do it.

The last time I had to work on that area of my 124 I had it on the lift raised up high enough that I didn't have to bend over. It made the job MUCH easier on the back. It might be worth rolling the front up onto a set of ramps for the job.

Good luck.

I find that if I drive my car up on ramps for this kind of work, it helps alleviate the back problems since the car is higher.

Very true, however I on the other hand prefer to have the hood all the way up 90 degrees (that grill gets in the way), something not possible in my garage if I drive up onto ramps...

So are you saying....that when the water pump goes... you can't do it without this 55 dollar snap on part? Does sears having something similar?

I did it fine without the snapon tool, and I did not remove the PS pump or tensioner.

I used a Craftsman U-joint. The first one exploded but the second one survived.

You don't need the Snap On tool, but it works really well. It's a 13mm 12-pt head, and it's got a thin shaft that slips between stuff really easily. I tried using U-joints before, but the problem is they allow a lot of flex, which makes it hard to get torque on it unless the angle of the joint is just right.

I am not saying that you must have the tool. What I AM saying is that with the tool, I have been told that it is possible to get at the water pump bolts without field stripping the left front of the engine.

Benzmac, one of the early sponsors of this site and a pro MB tech, said this about five years ago. I do not doubt him, but I think it just works on a few particular versions, maybe only on a 104. The tool would be a worthwhile addition to anyones tool box that works on MB's, provided that the person can part with almost $50.