The radiator leaked at the bottom. The fuel injection pump leaked oil from a threaded shaft, which had backed out until it was riding against the control lever. It also leaked oil from the forward end of the control shaft because the plastic cap had deteriorated. The hose from the engine to the oil cooler had become hard and leaked at the reusable fitting.
The front shaft seal at the crankshaft had been replaced recently, but with the wrong part: The correct seal has a shoulder on the outside, which makes it seal against the block. Replacing the seal eliminated that oil leak.
On the right forward lower side of the engine there are some 8 mm studs for mounting the alternator bracket. They are now used for the installation of the air conditioner compressor. They were a little short and the installer backed them out a few turns: Because the threaded holes go into the crankcase, oil leaked along the threads.
Another 8 mm socket head cap screw at the right forward side of the cylinder head is always submerged in oil and the thread cut into the block emerges behind the water pump. There was a regular washer under the screw instead of a sealing copper washer. For good measure, I also install screws with MB anaerobic sealant. (MB A002 989 47 20 10)
The shaft for the timing chain tensioner is capped off with a bolt. A longer one to attach the new alternator bracket replaced that bolt. It leaked oil along the threads. It took one year to find and correct all the leaks. My garage floor now stays fairly clean.
The previous owner gave me all the invoices for work he had done: “Repair oil leaks” was frequently mentioned. One invoice from our local MB dealer shows an interesting item: “Seal oil leak previously repaired: No Charge: Leak unrepairable.” The previous owner had bought the car as a present for his wife. She drove it to the golf course a few times. It leaked so badly, it became an embarrassment. The floor of his garage always had oil on it.
The engine leaked one quart of oil about every 200 miles. An interesting comparison: My ’86 Toyota truck, with 210,000 miles, leaks two drops of transmission fluid standing overnight after driving. My daughter’s ‘89Toyota Corolla with 87,000 miles does not leak at all.
1969 280SL,Signal Red, A/T, P/S, A/C, Both tops, 3.27 axle. Retired engr. West Seattle, WA
