Hello.
Let me share recent experience with water pump / fan coupling rebuild.
My pump was leaking oil from shaft seal and the oil was sprayed all around with centrifugal force.
At first, I thought it’s possible to leave pump body on the engine block and remove just the pump. That’s not possible as there is no access to M6 screws holding pump to the body. You need to remove pump and body as an assembly from the block. Follow MB workshop manual to do it.
The only struggle was that comfort hydraulic line is blocking access to upper screws so it’s necessary to remove and bend out the line. Crankshaft pointer serves as one screw too so it’s necessary to use very deep socket for removal.
Disassembly is quite straight forward process well described in workshop manual. I had only couple of issues.
1) It was impossible to put wrench nor socket on one M6 screw holding pump to the body as the screw head is hard to access. I used chisel to turn the screw with hammer. This screw will be replaced with to Allen head screw for easier future disassembly.
2) It was almost impossible to remove front primary shell from the driven plate. I had to use reverse hammer mounted to impeller side shaft end to separate it.
3) Removal of the inner needle bearings was nerve racking process. Especially the deeper one at the fan hub was a fight. Special inner bearing pullers are a must.
Everything was cleaned, screws replated and black parts repainted.
Next, I realized that the original repair kit from MB is NLA so I started buying parts separately. To help you here is a list of parts you need.
The first number is the part id from Fig 20-3/1 of workshop manual.
11 – 2x Oil metal seal ring - A 186 277 00 55 – NLA, I was lucky at SLS shop in UK
3 – 2x Rubber o-rings - A 003 997 71 45 - for primary and secondary shells to driven plate/shaft
I got the ring from MB, but it’s nothing special. You can use NBR 70 ShA 125x3 rings instead.
10 – paper gasket (called a shim in the Fig) - A 100 201 09 80 – NLA, I used 0,5mm thick Reinz AFM gasket paper to make it.
5 – radial seal ring - A 003 997 06 46 - seal with metal case 38x55x10 type B2 NBR (also known as WC type) – I bought it overpriced from MB.
30 – needle bearing - A 001 981 08 10 - HK 2216 Needle Roller Bearing (front-end of bearing housing) – MB will sell you INA made in Slovakia. You can use any HK 2216 of you preferred vendor.
19 – ball bearing - 6003 C3 (back-end of bearing housing) – do not use 2RS covered bearing as it’s getting oil from outside – there is a small hole to supply oil.
9 – rubber seal ring - A 189 206 00 60 – NLA – I used 30x2 FPM70 o-ring but NBR will work great too.
13 – radial seal ring - A 004 997 85 46 – NLA – use basic 17x28x7 NBR seal ring – I tried to use FPM but the seal lip is a bit deeper and was riding on pitted part of the shaft causing leak. (humidity will get there through the drip hole).
14+15 – water seal and sliding disk – get A 000 201 98 19 from MB. It’s a modern ceramic replacement kit that contains both parts.
16 – impeller - A 100 200 00 04 – Most probably needed as you will wreck the old one during disassembly by puller. This part is 400 USD so I decided to design and CNC machine bronze replica. I can offer them for half the price. Check the pictures bellow.
26 – 2x needle bearing for fan hub – The MB part number is WRONG. You will get much smaller bearing compared to the one pressed out. Get two HK 1816 needle roller bearings and you’ll be fine
23 – radial seal ring for fan hub – A0019972646 - It’s 100 USD from MB – I decided to use DPH 19998 instead. It’s a 35x52x10 B1 seal NBR (also known as WB type). Don’t use anything else as there are tiny oil drain holes that may get covered by wrong seal type.
C – cupper seal ring - N00760312405 – just use 12x15 Cu and don’t by 4USD one from MB!
Additional parts not from Fig 20-3/1:
pump to housing paper seal - A 100 201 13 80 – I bought it from MB but it’s just a paper seal made of ElRing EWP210 0,5mm thick
2x housing to engine block paper seal for inlets - A 100 201 14 80 – paper seal that MB is selling 50 USD per each and you need two! I will cut it from Reinz AFM for free. I will use 1mm thick variant.
housing to block paper seal for main body - A 100 201 15 80 – NLA – I will cut it from 1mm thick Reinz AFM.
600 #796 (1967 US version)
300SEL 6.3 #1285 (1969 EURO version)
300SEL 6.3 #5346 (1971 US version project)