benmack1, the low coolant level indicator lamp on the dash should have illuminated before the coolant expansion tank was empty. I would check that the float switch is functional and that the indicator lamp illuminates when you turn the key to Position 1. Check your Owner's Manual if you're unfamiliar with these terms.

Presuming you're using MB coolant in your 1995 E320 a white residue will result at any leakage points in the cooling system. Check all hose connections at the expansion tank, radiator, auxiliary water pump and water pump, plus the water pump weep hole ... which will leak coolant if the seals are shot. If you need a new water pump it's best to buy a reconditioned water pump from your local MB dealer. The upper radiator hose connection can break off on older cars ... grab the upper radiator hose when the engine is cold and check that the connection is secure. If the hose connector is cracked best to buy a new Behr radiator.

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Fred Hoelzle