My '69 280sl, automatic, had an engine failure "horrendous rod knock" at about 86,000 mi. The owner, my son (now deceased) had Metric Motors rebuild the engine. Over the next ten years, he put perhaps 2,000 miles on the car, and probably did not follow normal procedures for recheck of the head bolts and valve clearance, nor oil changes. The car then went into storage for three years.
I have had the head bolts (somewhat loose), valves, all fluids, etc. serviced, and the car runs quite well, The engine is quiet, powerful, etc. However, it smokes VERY BADLY, and uses about a quart of oil every 400 miles. It is an embarrassment to drive!
The plugs are oily, with lots of carbon, as would be expected, but are not fouled.
The common diagnosis is that the rings and cylinders were never broken-in properly (very bad news), or that the valve seals have deteriorated from lack of use (much better news).
Suggestions have been to do compression tests, leakage tests, bore-scope inspection, etc., which I will probably do.
Any members' confirming experience, or other opinions, would be most appreciated.
It may be interesting that I maintained a 190 SL for 43 years, and sold it recently with 303,000 miles. I replaced the cylinder head 35 years ago, and had no further problems with it. It did not smoke, and leaked more oil than it burned! (Note: purchase price: $1,700; sale price $79,000.) It pays to keep these cars up.
