AH - I was wrong then. I was thinking back to my days of tuning up my grandfathers john deere tractor, I had to replace a fuel seal on the IP. When all was assembled I could not turn it off! it ended up being way out of time and I thought maybe the MBs ran off the same principal. MY bad.
(that’s what I get for trying to relate a 60’s American tractor to a german diesel)