Thanks for the great replies and the pics - much appreciated.

I can't even get a look at the seep hole - I'll try again this afternoon. This pump was not leaking before this incident (car overheating due to the broken radiator nipple), so I'm guessing that the overheating has caused either an o-ring leak, or even possibly an internal leak in the pump itself. Do you guys think this is likely?

Just trying to make sure before I go to the trouble of pulling the water pump - which doesn't look like an easy job on this M104 motor.

ryan

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RG Newell

1984 300D
1972 250
1986 560SL
1991 300CE

It theory you are correct.
But since this is the Tech forum I used the practical aspects of boiling water in an engine. It the water looses pressure it start to boil, the vapor that comes of it (after a while) will be around 100C. The little bit of water and vapor that is left is also very easy to cool by the radiator.

The effect is that the temp will go up to max and drop to 100 again.
IF you don't see the steam coming from the engine bay (driving fast) you may think everything is ok until there is so little water left that the cooling fails completely and the temp will go up again.
By then you have a serious problem.

Rob

The first wife drove a 4 cyl Mazda to failure like this where it started steaming then finally shut down. She cooked the rings in it. I never did get an answer from her wha the temp was indicting. Thankfully it did not stop until they got to within walking distance of the mall they were headed to.

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Jim