After a year of frustration I finally found the source of my antifreeze leak. Its the water-pump housing. The part into which the thermostat mounts.

The leak is extremely small and does not show-up when the system is pressurized for testing. I found it by pure perseverance.

I tried to tighten the thermostat bolts, but this did not help. I then changed the thermostat and gasket, Did not help either. I then noticed that the inside of the aluminium water-pump housing is pitted, and the thermostat gasket can not seal properly. I don't know why it pitted. I have been using MB antifreeze, and so was did the previous original owner.

The leak is very slow, maybe 4 Oz every 800 Miles. Now that I know where the leak is, I can live with that. I am just glad that its not the Head gasket or the heater core. I would like however to fix it. Short of buying a new water-pump housing, any suggestions on how to fix the pitting so that the thermostat gasket can then form a tight seal.


Thanks

Phil

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'95 E300 Diesel, 264,000 Miles. [Sold it]