Internal and External engine oil & coolant leaks can develop from the head gasket and/or timing cover gasket; these leaks should be repaired before the engine oil and coolant intermix which can result in severe engine damage.Google+
Car Problem Reports
Mercedes-Benz 300TE 4MATIC Repair Leaks From Head Gasket/Timing Cover Gasket Before Oil and Coolant Intermix
Mercedes-Benz 300TE 4MATIC Problem
Visitor, 1991 Mercedes-Benz 300TE 4MATIC, 175,000 mi
Head gasket has limited life on these engines; MB tech says this is a known weak point but MB has not upgraded material. Replaced the first at 118,000mi. At that point it blew with high revs and got coolant into combustion chamber - loss of power. Second time was gradual failure and got engine oil in coolant and caused cooling system to fail - hoses ruptured and rad gummed up.