New engine knock 300SD
 

I just had the long block changed in my 300SD,And the motor has less than 6000 miles.But now there is a loud knock in the front of the motor and it seems to not be fireing on one cylinder.Could this be a valve train problem or something different?The motor was installed by a certified MB mechanic and the motor is a new long block from mercedes and is under warranty but the car will not make it to the place I had it installed.Plus I do not have a manual for this car with all the technical data.Can the forum help me????? :confused:

Knock
 

Does the knock seem 2b coming from the cylinder that is not firing? Try cracking open the line at the injector while it is running. If the noise goes away, most likely faulty injector. It could be other things, but I always start simple. Eliminate the easiest/cheapest items first. You could get lucky.

Call 1-800-FOR-MERC and ask them about having it towed in. The warranty should cover the towing and all labor costs involved in fixing the problem.

Here is a recent thread that is close to your question.

http://www.peachparts.com/shopforum/showthread.php?t=105557&highlight=knock