My 1976 300D Engine 617.910 overheated this morning and after I shut the engine down and opened the hood I noticed water on the pavement . The water was dripping down the front of the engine from behind the fan. The hoses are OK so could it be leaking around the water pump?

Any help will be appreciated.

I would think the water pump would be a great place to start. I've never replaced a 300D water pump, but it should be fairly easy. The pump should have a weep hole on the bottom side of the shaft. Should the bearings fail, water runs from the hole. It has probably been seeping for a while for it to have overheated your engine from coolant loss.

Huge pain in the sitting part -- start by taking off the fan, shroud, visco clutch, and belts.

You will next need to take a good look and determine if you can remove all the bolts that hold the water pump to the housing. One the four 220D it is necessary to remove the AC compressor bracket to get to one bolt (!). This is not easy! On some models it is necessary to discharge the AC and remove the compressor beacuse there isn't any place to set it aside connected!

To do this, you will need three bolts with the head cut off and a screwdriver slot cut them the same size as the three bolts that hold the bracket and pump housing to the front of the block. Remove these three bolts and screw the ones without heads in to hold the water pump housing in place (not really necessary coming out since it is very unlikely that the gasket will survive, anyway, but you can try!), then remove the five or six bolts that hold the AC compressor bracket on and pry it out of the way -- it slides over the front of the pump housing and off the three bolts on the passenger's side -- one on the manifolds and the other two on the engine mount bracket.
If the pump housing stayed put, replace the bolts with some extra washers so you can take the bolts that hold the water pump to the housing out. Else remove all hoses and take pump to bench.

There is a cut-out in the harmonic balancer that lets you get to the one bolt otherwise impossible to reach. Unfortunately, I don't know if this is universal!

The housing is aluminum -- have a care not to break off any of the small bolts! Use anitseize (NOT aluminum paint!!!) on the bolts going back in.

Replace the short hose behind the AC bracket while you are in there -- it's cheap and the only way to get to it is the above!

Installation is the reverse -- use the three headless bolts to hold the water pump housing in place while prying the AC bracket over the front of the pump -- it's a tight fit! Use aircraft permatex on the new housing to block gasket, and make sure it stays put -- very hard to see when going in!

This costs the earth to have done -- one of the times it pays to learn how just to save about five hours labor!

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!

While the water pump is off, be sure to replace the short bypass hose down there. It is virtually impossible to replace that hose with the water pump in place. It is probably hard and may be leaking a bit.

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Palangi

2004 C240 Wagon 203.261 Baby Benz
2008 ML320 CDI Highway Cruiser
2006 Toyota Prius, Saving the Planet @ 48 mpg
2000 F-150, Destroying the Planet @ 20 mpg



TRUMP .......... WHITEHOUSE
HILLARY .........JAILHOUSE
BERNIE .......... NUTHOUSE
0BAMA .......... OUTHOUSE

I did the water pump on my '78. it was much easier than described for the 220. it only took about an hour and I work slow.
take off the fan blades, loosen the belt, get in there with a 10mm open end wrench and get the rest of the stuff out of the way. careful - don't round the heads off, they were a little round to start with on mine. then you are looking at the pump. I had read somewhere else that these are actually cheaper at the dealer than many other sources - this was true for me. it was about a $25 part. If I had to do it again, I would take the fan shroud off, it is easy and will give you a bunch more room.

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andy t
'78 300d
'95 volvo 850, wagon
'86 300sdl - engine out, maybe I'll have it rolling by June

whole bunch o' bicycles

I believe the '76 300D is a 115 chassis and the "78 is a 123 chassis, so I'd listen to psfred on your 1976 300D 115 chassis. Sorry YMMV.

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The Golden Rule

1984 300SD (bought new, sold it in 1988, bought it back 13 yrs. later)

A 76 300D is a W115. Water pump is easy if it doesn't have AC (and they all do!)

I also forgot that there is a little steel bleed line from the water pump housing to the head -- remember to put this back on before you put the AC bracket back on! It can be replaced after, but only be feel -- I had to buy two sets of copper seals since I ketp dropping them and couldn't find them on the oily gravel drive!

Peter

__________________
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!