Hi Guys, okay, I have my 300D started. Thanks ! (one faulty brand new glow plug needs to come out though - argh)

My new problem is that the car is overheating. I checked the thermostat and it works nicely. However, the rad is staying cold while the engine is overheating. I take off the rad cap and I notice that the water is not moving past. Just sitting there and not getting very hot. Does this mean the water pump is not working?

If so, where is the water pump? Is it belt driven? I see a belt going to an alternator, air conditioner, and some other contraption that seems to have oil lines going into it.

There is no coolant leaking anywhere and there is no rattling noise. Does this sound like a water pump problem?

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1975 300D

The fan and pulley are mounted to it.

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1982 300sd, new project car to restore

It doesn't matter if you know what you're doing, as long as you look like you know what you're doing.

No, it needs to be bled, had same problem with my '75 300d. Open heater valve, put front wheels on ramps to elevate front end. Find heater hose exiting block on driver side and discount at heater valve so you can use a funnel and fill block this way via heater hose -this way nearly eliminates air bubbles -pour coolant in slowly and wait a few minutes between funnel fills -good luck!

Warmblood, by heater valve, do you mean the heater control on the dash?

Just curious, if the water pump was working, how come the water does not circulate in the rad? Would an air lock cause this?

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1975 300D

Okay, thanks, I did what you said, although not as precisely. I put the car on ramps and added some fluid via a funnel into the hose that goes to the block. It seems to have worked. The car is not plated so I can't drive it to be sure, but I let it idle for about 10 minutes and it started to overheat a bit, but then settled back down to about 175. So I will assume for now that whatever air might have been stuck in there escaped through the rad cap. At least now the rad seems to be getting hot. I still don't see much movement of the rad fluid, but the temp did seem to stabilize at the mid way mark.

Thanks a lot!

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1975 300D

FWIW I've had the same issue arise with my '76 300D a couple times now. Bubbles seem to be kinda persistent in these.

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Finn John -- Albany, Ore.
www.offbeatoregon.com
76 Merc 300D, sky-blue, *86k, for driving
84 Jaguar XJ6, black, 245k, for restoring someday
71 Merc 408, 2.3 petrol 4, Avon caravan conversion (UK), RHD