I'm new and really need some help. I will seek a mechanic's point of view locally but would appreciate some expert advice before reaching into my pockets.

I inherited a 1982 380SL that had been sitting for two years. After replacing an electrical relay and the fuel filter, I got the engine running smoothly. It blew alot of blue smoke and then ran fine except for a knocking noise in the engine. Due to the circumstances, I proceeded to drive it 1,300 miles from Michigan to Florida with no problems. (I never exceeded 2000 rpm)

It makes a knocking noise at the passenger side rear of the engine that coincides with the engine rpms. I pulled the valve cover and ran the engine for an observation. I did not see anything unusual with the cam, rocker arm or lifters.

It runs fairly well but it is a little difficult to tell becuase the exhaust needs replacing. It may be a little sluggish but starts right up and runs smooth. I was told that the engine would have come apart during the 1,300 mile trip if it was really serious and that it may only be a poor lubrication problem.

Any ideas before I take it to a shop?