The Maxipad is bad!
I had a loader I had to look at in one of our Ag stores, a Doosan with a Bosch common rail fuel system. The machine had a knock at idle after it was warm. It also made several distinct knocks when turning over before it started, from the rear of the engine. (gear train area) Those sthi spreader mechanics pulled the head off to see if the valves were hitting the pistons!
They changed 1 injector and then were stumped. I went up, checked the fuel pressures with the laptop, which they don't have, and they were ok, then went thru a bunch of other stuff. The tech up there told me that they checked it with a temp gun and the #1 exhaust port was a lot colder than the others, so they replaced that injector. I did the same thing and found 1 that was 50* higher than the others. I think the injector is stuck open, so they were going to replace at least that one, maybe all of them.
The knock when turning over? It was the starter. I pulled it out and hit the key, and it made a knocking noise sitting on the frame. That's a 1st for me.
Pretty sad when the factory rep tells them to call and have me come out when they are the dealer too. This is the 2nd time this has happened, and a different branch too!