Ok, well the honeymoon with this recent toy is over. I came home to find coolant splashed all over the garage floor, coming from the water pump. So i ran over to Prestige Mercedes and picked up a new water pump, thermostat, and upper/ lower coolant hoses. Total cost: $228.30- Not Bad right???!!! So I will tackle this job tomorrow, it's the first time i have done a water pump. I dont know what to expect.....

So far I have had the leather re-dyed, the hood pad replaced, changed all plugs/ wires, changed air-filter, paintless dent-removal, and a full detail. This baby will be like new!!!!!!

Any reccomendations when tackling a water pump on an M103?????

Perform a search on water pump replacement and you will find more info than you would need. With the info found on this site I replaced my pump and knew exactly what to expect. While you are at it make sure you are prepared to replace the belt tensioner, mine was shot and its good to take care of it all at once. Also make sure you replace the short hose between the pump and block. Spending a little more money and time now will make things easier in the long run.

Not a complex job to perform, but I hope you have very small hands/fingers and the proper tool to get that ""behing everything" rear bolt on the water pump.
Took me a full day to do the complete job, and my back hurt for 3 days afterwards.

6 hours start to finish.

The only really bad part is the rear bolt, as mentioned. This would be easy if there was not a power steering pump in there.

Do not remove the bolt that holds the heater hose pipe -- it's slotted, you can just loosen it and push back.

Replace the short hose between pump and head -- no way to get to it without removing the water pump.

The really bad news is that you will almost certainly need a new belt tensioner -- the "spring" is rubber, and it is usually shot, and if you try to use the old one with bad rubber, you break the tensioner bolt.

Loosen the center main bolt on the tensioner and watch the little plastic pointer as you loosen the 13mm tensioner bolt -- if the pointer doesn't move back the the start of the "ramp" cast in the tensioner body as you loosen, you need a new one ($$$ -- more than the water pump, I think). This is a one-way trip -- if its' bad, you cannot get the belt tight enough to drive it once loosened.

When refilling, pour in as much coolant as it will hold, then squeeze the upper radiator hose flat, pinch the small hose from the top of the rad to the coolant tank flat, then let the upper hose go. Coolant will be sucked out of the tank into the engine. Repeat, filling as needed, until it won't take any more. Usually you will be a gallon short if you don't do this, and will overheat it when the coolant suddenly "disappears". This technique will usually even fill the heater core.

Peter

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

Removing the fanbolt was fun on my car as well. You really need the special socket (8mm stubby), I tried a cut-off allen key with a 8mm wrench but it broke. That rear bolt was a piece of cake after that.
I also replaced the tensioner, idler pulley, shock absorber and the aforementioned hose. Good luck.

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