Just replaced the injectors on my '74 240D with on-spec rebuilds, using Monark nozzles. Since replacing them, I have noticed a more audible ping coming from the engine. Sounds like a marble is clanking around in it. It was there before, but sounds louder and more pronounced now. It is not regular...like a ping.ping..ping.....pingping...ping...ping. (sorry, only way I know how to describe it in writing). Anyway, oil pressure is good, it fired right up afterwards. Cleaned out the injector sockets really well...was careful not to get anything in the piston. Put in new heat shields, etc. So, what's up with the noise? In addition, only a couple hundred miles since a valve adjustment. Thoughts?