Help with 75 300D water Pump - PeachParts Mercedes-Benz Forum

j.pelchat · #1 11-04-2004, 10:23 PM

I have searched the site for info on replacing the w/p on the 75 300D and have found none that gives me enough confidence to go ahead and do it myself. I recently purchased this car and would love to be able to do such things but would like a little input.

The car has a non-functioning a/c unit and mount in the way of the w/p. Looking at it, it seems pretty strait forward except for the fan assembly and a/c mount. Would it be a good time to replace the little coolant hose between the thermostat and pump? Please provide insite on the process. I assume a good parts shipper would send all gaskets and rubbers.

tangofox007 · #2 11-04-2004, 10:40 PM

If you plan on working on the car yourself, I would highly recommend that you obtain the Haynes Manual for the MB Diesel. Many chain auto parts stores carry them. The manual covers a number of routine procedures.
I would also recommend that you do not purchase an aftermarket water pump. The water pump is one of those rare items that is cheaper at the dealer. Plus aftermarket w/p impellers are sometimes not what they should be.

psfred · #3 11-04-2004, 10:44 PM

Check for a clearance slot in the balancer for access to the water pump bolt on the bottom -- if you have it, you can remove the pump without taking much else off, it not, you have to remove the front balancer. Some have the slot, some don't, so you have to look (my brother's didn't).

If you have to pull the balancer, do a search on the proper procedure for re-installation, you must align it properly while going on and you cannot use the steel location pins to do this, they dig in and ruin both crank and balancer, a big ugly...

I don't believe you have to remove the AC compressor bracket on that car, but if you do, you need three spare bolts the same as the ones that bolt through the AC bracket AND water pump housing. Match for length, then saw the heads off and cut a slot in them with a hacksaw so you can use a screwdriver to install and remove them. Remove the water pump housing/AC bracket bolts one at a time and replace with the studs you made, screwing them in so that the bracket will slide off over the "heads". R&R the bracket this way, unscrewing the headless bolts and replacing them one at a time when finished if you need to remove the pump body (rather than just the bearing and impeller part).

If you do not do this, the body to block gasket will slide out and leak.

You may not need to do this on the 617, I don't remember. If the AC bracket bolts go through the water pump body, you do.

Yes, if you need to remove the AC compressor bracket, at least inspect the hoses on the water pump/thermostat housing. Replace if at all iffy, they are cheap and it takes a couple hours to get to them.

Peter

Peter

Palangi · #4 11-04-2004, 10:46 PM

The Haynes 123 book is good to have for general questions, but will not be too helpful for this specic job on a 115. Just keep taking off parts until you get to the water pump. The pump itself is exactly the same one as a 123 diesel, but there's a lot more stuff in the way.

tangofox007 · #5 11-04-2004, 10:54 PM

You're right. My mistake. The Haynes Manual starts with the 1976 models. Did not have my bifocals on.

Palangi · #6 11-04-2004, 11:02 PM

Looks like PSFred has it covered.

nachi11744 · #7 11-05-2004, 01:00 AM

Hello,
You will have to remove the A/C bracket to get to the waterpump on a W115/OM617 car. IIRC, only the early 1974 engines did not have the slot in the crankshaft balancer, so you may not have to remove the balancer assembly.
Hope that is of some help.