It's been several months since I originally polished and reinstalled the delivery valves in my SDL, so it's time for an update.

Recently I've been getting an intermittent nailing that comes and goes. I can never seem to catch it in the act, but did so the other day. Tracked down my suspect to #6. Checked the D/V and it looked fine, but swapped it anyway. No change. Pulled the injector and did a pop test to find it "peeing" instead of chattering. No good! Swapped out with a different injector and the nailing stopped.

HOWEVER, now that the loud nailer was gone, I could hear light nailing from another cylinder only at idle. I took a mechanic's stethoscope and decided to get scientific on pinpointing which cylinder was making noise. I narrowed it down to #1 based on the different sound it was making. When listening to the injectors, I found it was easiest to place the probe in a position that touched both the injector line nut AND the injector line. Good injectors produced a metallic "tink" noise, while #1 produced a "tikka" noise, very undefined compared to the others. I think this may be a key clue when trying to diagnose a D/V as a nailing suspect.

In the case of #1's nailing, I found that I installed the D/V I lapped UPSIDE DOWN! Very much a Mea Culpa moment there. I flipped the D/V over and buttoned it back up and #1 stopped nailing immediately.

There was still some injector knock, nowhere near as pronounced as #6, or even #1, but audible enough to annoy me. I tracked it down to #4 by cracking injector lines to find the culprit. I pulled the injector to pop test and found it also peeing like #6. Swapped in a different injector and I now have an OM603 running as quiet as it can. All you really hear at idle is the D/V's clicking, it doesn't hardly even sound like a diesel.

So for those keeping track, the D/V lapping does seem to be holding up. Other than #1 which some idiot (yours truly) installed upside down.

Somewhat concerning to me is the short duration that the injectors held up. I have Monark injector nozzles and took the time to balance the pop pressures within 25 PSI of each other. The 2 injectors I'm having problems with still pop right at 1950 PSI where I set them, but the pee stream is a bit worrying. I'd have expected them to last longer than that. I'm now running on a mix of 4 Monarks and 2 Bosch nozzles. Car seems to be happy, so I'll leave it like that for the time being.