I finally fixed a 6BT Cummins injector knock after months of headaches

Working on a 1995 Dodge 2500 near Denver last month, had a #4 injector that sounded like a hammer on idle. Swapped injectors, checked timing, even pulled the valve cover to look at pushrods. Turned out the copper washer on the injector was the wrong thickness by like 0.5mm. Anyone else run into a simple fix that took forever to find?

3 comments

3 Comments

finleyh891mo ago

Copper washer thickness is one of those dumb things that'll get you every time on these engines. Bet you won't forget to mic them before reinstalling next time.

lisaf3817d ago

100% feel you on that "found it after way too long" vibe, that copper washer thickness is the sneakiest thing. I had a Ford 7.3 that clattered for three months and it turned out to be a stupid washer that was just a hair too thin, drove me nuts. Once you swap that little piece out it runs like a dream, but man does it ever make you feel dumb for not checking it first.

joelh641mo ago

Copper washer thickness is a common culprit on these old 6BTs, but saying it took months to find seems a bit much. A quick multimeter check and a compression test would have narrowed it down way faster than swapping injectors and pulling the valve cover. Not saying it wasn't the issue, just that the troubleshooting could have been way more efficient.