The next morning after my 930 mile one day holiday drive I find the classic coolant puddle dripping off the oil pan. Most likely the water pump from what I can find in the archives here.

However, the goofy thing doesn't seem to drip noticeably while it's running, only after it stops. I let it sit for the past 6 days and it lost the overflow tank contents, took about 1/2 gallon to fill it back up.

Is this normal for a water pump to only leak while sitting, or should I be looking for something else like a thermostat gasket?

I have no idea how many miles are on the pump, I bought the 300 SEL about 12k miles ago and it now has 162k.

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(2) 1988 300 SEL W126