Within weeks of getting my W124 300E 2.8 back on the road again with a new transmission, (amongst other things) it's developed a coolant leak and I can't seem to be able to trace it.

When I pour coolant into the expansion tank, it almost immediately pours out of where-ever the hole is. It does slow down after a while and stops pouring out when the water level is just above the coolant temperature sensor but I have seen the tank empty after the car has been sitting for a few days and the coolant has steadily dripped out.

Looking under the lower engine shield the coolant is running from behind the A/C Compressor and along the side of the oil pan and then onto the lower engine cover. The bottom of the radiator is dry, I don't suspect that. I also don't suspect the head gasket as the water doesn't seem to be coming from the passenger side (where I believe the M104's leak most often) and I had it replaced back in 2005. I can't see an obvious water leak from the top of the engine (but I've not discounted the fact that I'm looking in the wrong place).

I had the water pump replaced in november 2002 (about 60,000 miles ago). Is it time to get this replaced again or could something else be wrong?

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Steven Harrison

1993 300E2.8 - 196K
2001 E320 4MATIC - 86K