So I bought this 95 ford f700 with a 5.9 in it and it is knocking. I couldn't hear it knock because of the terrible noise coming out of the tranny which I knew was bad. In any case it don't sound in the lower end so i haven't pulled the pan yet. I adjusted the valves and then it was still knocking so I cracked the lines on the injectors till the noise quit, which was on number 6. I pulled that injector and had very reputable guy who does it for a living test the injector and it is good. He said it could be in the diapragm washer in the injector pump could do this as well. He told me to test it by taking all the lines off of the pump, pour oil on the top of them, put air to the incoming fuel line and if bubbles come out washer is bad. I suppose I need to plug the return on it but I forgot to ask. I couldn't find any info on this anywhere so I wonder if I am barking up the right tree. The noise gets better as it warms up and almost stops at higher rpms. It always loud at an idle. Oil pressure is in the normal range. I used a mechanics stethascope and couldn't not get any noise from the pan so I am still thinking higher like a wrist pin. The truck has 250k on it. Would a wrist pin be a likely culprit? Is it a common problem in these engines? Any input would be tried and appreciated.

 

Has the pump been turned up? Mine is doing something similar. I rolled in new bearings, checked the flexplate for cracks, adjusted valves, cleaned and reset injectors to spec, checked DV's, and all was good. Last weekend I took it to dodge and the service manager, who has owned a couple of trucks like mine, said that my engine sounds normal, but the lift pump might not be making enough pressure to keep up with the injection pump. The reason I say all this is if your fuel pressure isn't up to par, you could have that knock at the back of the engine. I thought I had a wrist pin problem too.

 

Being a two ton truck I doubt anyone has done any performance mods. The fuel pressure is a good idea though. I will check it and see what it is when I get a chance.

 

Is this a p pump