Well, after drag racing my SL for a total of 9 runs (she did well running in the high fifteens) my engine in now making a knocking sound... I don't have any more info at the moment but I'll be back in a bit to post when I know more... I'm hoping with an oil change it will magically go away but something tells me that's not happening any time soon....

 

Changed the oil today and its still knocking. Drove it down the block and back and there is no improvement. Any ideas?

 

Your primaries or secondary cats may be shot. They may have finally given up after all that back to back stress of 9 full passes. They make a TERRIBLE rattling sound that sounds like there is marbles in the engine. Get under neath the car and push the gas pedal with your hand, see if you can hear the rattling coming from the primaries or secondaries. If so, then consider yourself lucky: time for high flow cats .

 

it knocking or ticking....?? it could be your cam oil feed tube that cause the problem.....
read here...

http://www.benzworld.org/forums/r129...e-ticking.html

 

Sorry to say... but your car should be running more like 'mid fourteens'.