I have an '89 240 automatic, and I've had an unusual problem for the last few weeks. Once I get the car warmed up and running, I occasionally hear a strange scraping noise coming from the vicinity of the engine. When I change speed, the noise changes volume or goes away. It occurs most frequently around 60-70 MPH or inbetween gears, at any time when the engine seems to be working hard. I've already tried cleaning the carberateur with gas additive to see if it was some sort of problem with carbon buildup. All the belts, wiring, fluids, etc seem to be in perfect shape, and I've even checked all the heat sheilds, etc, to check for someting that may be rattling or vibrating. I suspect a timing issue, and would like some feedback or suggestions before I have the work done. Thanks...