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2001 F350 Crew Cab Dually 7.3
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Discussion Starter · #1 · (Edited)
Hi All,
I have been trying to figure out a problem for a while now. Decided I better join and ask instead of tiresome research. I will give the long list of things I have tried also. My 01 has what I thought was a fuel knock now for some time. I originally thought it was a rod like everyone else with their first PSD. I build race cars and engines so have a pretty good knowledge of mechanics. I have isolated this to cylinder #8. At idle and beyond there is a solid knocking coming from the engine. It goes away some when coasting, but not much. Started out somewhat faint but has become worse over the last year or more, which makes me believe it is not a rod since that should have come apart by now I would think. No mods to engine. I have done all work myself to truck. Oil changes every 3k or so. 530k on engine. I bought with 480k. It has pretty good puff of smoke when started but goes away fairly fast. At times it starts and make no noise for a few minutes regardless of air temp. Once warmed up it will always knock when running or started. Sooty on body near exhaust exit location.

List of things tried or done:
1) New Alliant injectors about 40k ago or so since old ones were tested when cups were bad when I bought truck.
2) Cut open filter to check for metal-None which was a relief I thought
3) In tank fuel mods done with pre filter to pump- no change. Also fuel rail crossover
4) Fuel pressure-65 at idle but did not check on road since gauge is not long enough, but since problem is at idle too I figured road test was not warranted. I could be wrong on that
5) New fuel filter(s)
6) Downloded app on phone and checked HPOP pressure and duty cycle. Was what everyone said should be. Been few weeks and don't remember those numbers and app is acting up now to recheck.
7) re torque injectors to 120 inch pounds.
8) Checked all rocker arm torques
9) Ran with valve cover off today and pulled injector wires till #8 made knock go away. Sounded really good at that point with it unhooked. Quieter than I ever remember actually.
10) Pulled #4 and #8 injectors and changed locations- no change. Sound still goes away when #8 unplugged
11) new ICP since was oil covered
12) Probably need to do compression check next
13) pulled hair out reading and thinking.

I really don't want to think about what is probable at this point. I do have access to a 7.3 f450 that only has 150k or so on it and runs perfect. New trans also. I can get for relatively cheap but don't really want to do an engine swap, but may be in need of it soon I guess. I was trying to fix this issue so if I do swap and it was something else I would not have same issue with new engine. Oh, it seems to have quite a bit of blow by with valve covers off, but figured due to milage that could be normal with ring wear etc.

Any help or suggestions would be greatly appreciated and would try to return favor if needed. If not Ford related I know construction and real estate well and also drag racing and engine stuff for that. I also rewire race cars for people.

Thanks, Rob
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