toopoor2fix
New User
I have a John Deere 4020 Diesel that developed a miss. The first step to cure miss was to remove the pencil injectors and have them tested. All cracked/popped adequately, however, 2 of the injectors test pattern was not real good if pressure was added slowly so I replaced them. This did not cure the miss. Turned out miss was a broken rocker arm on # 1 intake valve. After replacing rocker arm started hearing a ping in upper part of motor and isolated it to # 3 cylinder and suspected a wrist pin. When I was getting an estimate on what an overhaul would cost the mechanic asked if i had checked injectors. When I explained what i had done and that #3 cylinder happened to have one of the 2 new injectors, he suggested that I swap the injectors and see if the sound moved. He said if there were significant differences in pop/crack pressure between injectors it could adversely affect injector pump timing. Swapped #3 injector with #6 and the sound moved with the injector. Took all injectors out again and had the pop/cracking pressure checked. The originals cracked at 2000 psi and the new ones at 2800 psi. All 6 were set to 2800 psi (at Injection shop's recommendation). Now I have even more unwelcome "Diesel knock" chatter. Quiet at 600 rpm. Most notable between 1200-1700 rpms. Any suggestions? Looking at having all the injectors setback to 2000 psi and see if solves problem even though the mechanics say pressure should be in the 2600 to 2800 range. Tractor starts and performs OK, just noise is driving me nuts to the point I don't want to use it. My local "experts" don't think the change in pop off pressure would significantly change the amount of fuel allowed through the nozzle to cause or cure "Diesel Knock". Thanks!