i have a 2007 924g loader. It has developed a sudden knock. I did have cat come down and check the loader, to no success. They figured it was the lift pump, which i replaced. It did not change the spuratic knock that was occuring. We cracked the injectors, obvious idle changes occured except when cracking cyl. 2 & 6. Injectors were changed, worked the machine for 1.5 hrs hard and it seemed ok. Then at idle it started again. It comes and goes. It's one of those ghost problems. Fuel system ( filters, separators ) are very well maintained as this is my primary work horse for winter snow removal. It's best desribed as a " clack clack " noise, somewhat reduced power, very noticable when in 4th gear trying to accelarate. My next step is to try to get fuel from a 5 gallon bucket ( extremely clean bucket ) to rule out a filtration or fuel issue. Has anyone encountered this type of issue?
Generally it is the opposite cylinder to one that is firing 'hard' or knocking in the firing order that is causing the trouble. On a six cyl place the first three in order (153) over the last three of the order(624), that determines the 'running mate cylinder and if the hard hitting cylinders were 2&6 then look at 1&5. If for some reason they do not deliver enough fuel for power tansmission the mate makes up the difference, thus a fuel knock. I have one that knocks after load on a International Diesel tractor engine, I am going to have the nozzles rebuilt and flow matched as time permits, the electronic engines seem to be more sensitive to flow match discrepancies.
Maybe you have a lifter sticking? Just a thought. Had it happen to me once,,. Gramps
Change your oil filter and cut the old one open, look for metal, If it looks good take an oil sample and get it checked too. That will rule out anything structural in the engine. Have you checked valve adjustment? You in Ont or Alta? Later Bob
I have it happening in a 120H motor grader. I haven't done any troubleshooting yet so will be very interested in what you come up with. On this machine it started as the engine was warming up from a cold start and then became intermittent. At first I thought it was the air compressor but then heard the air dryer unload and the cackle was still there.
John, check your fan belts for a loose cover on one of them..... first thing easy that came to mind. lol