PeachParts Mercedes-Benz Forum - View Single Post - Delivery valve internal leak as a cause of nailing? Yes? No? Maybe???

Diseasel300 · #77 03-27-2017, 06:07 PM

Mine did the same thing. Stone cold start and it would fire up smooth as glass and quiet, then progressively run rougher and nail louder and louder. Was worst ~60-70˚ on the temp gauge (was LOUD!). After it got to operating temp the nailing would settle down some, but was always present and the idle was always "lopey". Get it up above ~1300 RPM and it was smooth as silk and would shut the nailing up.

Injector didn't help, DV seals didn't help, fuel pressure adjustment didn't help, lift pump didn't help, diesel purge didn't help. Changing the DV itself did help, and the recent highway trip finished it off. I replaced the DV on Thursday and have driven the car quite a bit since then and the nailing hasn't returned. The engine is a bit "clattery" until it reaches operating temp, but no more nailing. Once it gets up to 85 and gets nice and toasty, its so quiet you can hear the delivery valves clicking on the IP.