Well I know this is a fairly common question but I have some injector knocking that I don't know the source of. 190D 2.5, nearly 320K miles.

I had my injectors cleaned with the nozzles changed and balanced by Greazzer, installed them around 2000 miles ago. I changed the delivery valve seals and washers only about 100 miles ago because I had a leak on 2 of them which I assumed could be causing the knock, unfortunately I am not sure if I torqued them down right because I have a harbor freight torque wrench and I didn't know until afterward that I should have calibrated it before using it.

I honestly don't remember how long I have had the knock or if it started after I put in the rebuilt injectors. What I do know is that injectors 4 and 5 are pinging, iirc 4 is louder than 5 (using a mechanic's stethoscope and with feeling it). When I start up the car and it is cold this is very loud, louder than my 77 240D's idle, but if I drive it out on the highway and get the engine well warmed up, the engine quiets down a lot and runs a lot smoother though though those two injectors are still a but louder than the other 3.

I don't think I have any issues with air leaks in the fuel system but lets not rule that out.
The motor mounts are shot and probably contribute to the noise but I don't think they are causing it.
My guesses include the balance of these two injectors is slightly off (also unlikely) or my injection timing or engine timing are off. I have no record of if the timing chain has been replaced but I don't have any symptoms of the chain needing replacement.

Any other ideas?

__________________
Current: 1975 450SEL, 83 300D, 88 Yugo GVX, 90 300D OM603 swap, 91 F150 4.6 4v swap, 93 190E Sportline LE 3.0L M104 swap, 93 190E Sportline LE Megasquirt, 03 Sprinter, 06 E500 4Matic wagon.

Swap the injectors around and see if the noise follows the injector or stays with the pump.

The torquing sequence is said to be rather important.

Is it possible to reclock the barrels in this pump? On accident? Or the rack out of adjustment?

One thing I learned recently was to check the temp on the exhaust manifold for each cylinder with a laser temp gauge.

If the barrels are clocked wrong you can easily burn something up.

But did the knocking change when you replaced the seals?

I didn't notice a change with the knocking when I changed the seals. I may order some more washers and redo the delivery valves to the proper specs.
I should also order a generous number of injector crush washers to get all of that figured out.

__________________
Current: 1975 450SEL, 83 300D, 88 Yugo GVX, 90 300D OM603 swap, 91 F150 4.6 4v swap, 93 190E Sportline LE 3.0L M104 swap, 93 190E Sportline LE Megasquirt, 03 Sprinter, 06 E500 4Matic wagon.

I can't imagine that causing much of a problem.

I've resused both. First time my injectors came out there was no heat shields in there. Car ran fine.

I put some in. Been reusing as I work. Will put in a fresh set when I'm done playing.

I've seen the IP shop reuse the copper washer while working on site. He said it was wrong. But did it and it worked.