Hey,
I recently purchased from an auto auction an 86 300sdl with high miles >258000 (odo stopped). the car is very well maintained and in good shape. the 603 engine runs well with good power and has no blowby or oil leaks. A mercedes friend of mine offered today to help me check the injection timing with a mercedes tool (A/B light). We checked the timing and found that it was 20 degrees BTDC and normal is somthing like 14.5, so we adjusted the timing to this spec and the car runs well. After a bit of running around this afternoon, i found that the engine is making a rattling sound, not like a diesel sound, or nailing, but a more metal on metal sound. The sound is coming from the cylinder head area, and occurs between 1500 and 2000 rpms lets say. I have never noticed this sound before and its pretty disconcerting! Its not terribly loud, at first i thought i might have left a bracket loose or somthing of that nature, but no its definitely coming from the head.
I dont want to lead astray the theories that you might have, but i am concerned that the timing chain has stretched, accouting for the retarded timing, and today when we adjusted the pump we might also have disrupted the injection pump to cam relationship. Any ideas? I guess my next step is to check the chain stretch and see if this is the problem, but i figured i'd run it by the experts to see if this makes sense. Is this a coincidence? Is it possible that i lost a chain tensioner? has the chain gone slack and is rubbing against the timing cover or head? Any thoughts would be appreciated.
Also, we both inspected the timing adjustments and i am absolutely sure the injection pump timing is 14 degrees before tdc.
thanks in advance, patrick