Hi all, how are you today? Just wanted share something about the water pump and get some advice on parts and installation.

So, my 2004 CLK 320 cabrio decided to act up today. While driving in a silent underground garage, I heard a definitely non-Mercedes noise coming from the front end. A faint rhytmic screech. After opening the hood, I identified the noise as coming from the location of the large black pulley in the center (water pump). And I also noticed a funny wobbling of the said pulley From my past experience as Wrangler guy, that's a water pump about to fail

For those who might wonder how a failing water pump might sound and look, I filmed mine :


My currently installed part reads part # R 112 201 05 01.




It has an oil fitting going to the small oil cooler near the oil filter. Funnily this part number show up quite frequently as used part, but doesn't show up in any catalogue of new parts (as OEM equivalent). Using catalog search by VIN, I came up with current part number A 112 200 14 01. The one with the oil fitting. The other is A1122001501, w/o oil fitting. If I search by make/model/year, I come up with a variety of parts including 112 200 14 01, 112 200 01 23, 112 200 02 01 etc. It seems this pump fits a very large portfolio of cars. After methodical research, I narrowed it down to a Saleri SIL PA934A part. That I ordered. And will replace as soon as it is delivered.

Anyone has a clue why my part starts with an "R"? And how do you figure out for sure which part is a 100% replacement when you have so many references?

As for installation, I read a few write ups here and there including one at Pelican Parts. Some people reported having to thread some holes?? What's the deal? Why? Also I read somewhere some issues to fit an E12/E10 socket underneath the pump. I'm supposing to remove the torx circled that seems indeed quite close to the housing.



Any advice? Thanks in advance

 

Numbers that you find stamped on parts are not always the actual MBZ part number. They may look like they are, but they are sometimes the OEM's part number. Of course when buying used parts, the puller guys often just list them with whatever number is stamped. I always go by EPC.

As for the bolts, you need a good E-Torx socket set I like the Craftsman Max Axess sets - they are good at getting into tight spaces. Gear Wrench also makes some good for tight spaces. Note that those bolts are various sizes. I suggest using a poster board and drawing a diagram of the pump and its bolts, then laying them out on the diagram so you can keep up with where each one goes.

 

Thank you for your input Rudeney. A quick question: the new SIL pump comes with 2 gaskets. It's either one or the other gasket, right? If the flat, replace. If the thin rubber that fits in a groove... replace or not? What's the best practice?
My engine is the M112 3.2L (2004)

 

Correct - only one gasket is used. Do replace the gasket with the new one. It will be the thin rubber that fits into the groove in the block.

 

So, I'm sipping an ice-cold beer and relaxing after replacing the water pump of my 2004 CLK 320 cabrio. I want to share some practical experience that might help anyone planning to replace this part.

1
Get documented, collect the necessary tools and, really, don't be afraid! There are tons of write ups and videos that will guide you. It's an easy project. Schedule 3-4 hours if you have never done anything more than changing the oil.
2
Tools! You will use E10, E12 and E14 torx and17mm sockets, a decent torque wrench, thread-locking fluid, flat screwdrivers, large pliers, plenty of rags, some scouring pads (the heavy duty kind, for cleaning burned lasagna for example)
3
Drain. Trust me, drain the coolant BEFORE starting. You will save yourself quite a work. I didn't do it. I hoped there would be only a liter or so in the pump and ended with quite a large spill. It's very easy to drain the coolant. You don't even need to lift the car. Peek under the front spoiler. You will see a red thingy hanging from the bottom of the radiator. Slide a large pan that can contain 7-8 liters under the thingy. With a large flat screwdriver then your fingers unscrew the thingy all the way (don't worry it won't come off). Collant will start to flow and you can go enjoy a cold beer while the 7-8 liters of coolant drain out.
4
Make sure you have drawn the outline of the pump on a cardboard and marked every hole (and pierced). Place the cardboard within arm's reach and stable. When removing each screws, put a finger on the hole where it was, KEEP IT THERE! and search it's alter ego on the cardboard. Insert the screw there and only then lift your finger from the pump. It's very easy to forget where the screw came from. When re-installing, do same. Once you forgot the place of a screw, trust me it's a big moment of lonelyness.
5
Use the torque wrench to tighten the screws and don't forget the thread-locking fluid. E10's are 10Nm, E12's are 25Nm, the E14 is 40Nm, the idler pulley 10Nm (according my findings on the net). The procedure to thighten the screws is almost a war of religions between people. I don't care, I thightened all E10 first, then E12s and finished with the E14 and the pulley. So far no leak.
6
At least on the European model of the W209 320, there is no need to remove the fan or anything else. You own model might be different.
7
After spilling all my coolant, I refilled with regular tap water. I intend to drain again (since it's so easy) and refill with proper MB 235.6/236.6 coolant. Luckily we have a very soft water so it's not a problem for a few days. Mind that I refilled about 8 liters until the "check coolant" alarm stopped. I tried a hard drive in the city by 35°C (95F) and cooling normally. Highest temp observed is 100C (212F) at one moment. But then I remember seeing 120 driving up some alpine passes. So far I'm happy with the result and my ice-cold beer

The most difficult part? Honestly? Scrubbing the traces of the old gasket, and trying to keep the new gasket in place while attempting to re-install the pump. That part alone makes you wish you had 5 hands...

Thank you all for your invaluable inputs, advices and good mood )))))
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