Hi,

I know this has been covered many times, but decided to start a new thread since so many things can be a cause, and I have addressed many of them already. I have been trying to figure out a problem for a while now. Decided I better join and ask instead of more hours 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 other than 4" exhaust. I have done all work myself to truck. Oil changes every 3-4k or so. 531k on engine. I bought with 480k at a steal. It has a pretty good puff of smoke when started but goes away fairly fast. Also cranks a bit to start. 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. Soot on body near exhaust exit location. Noise is isolated to cylinder #8 after testing.



List of things tried or done:

1) New Alliant injectors about 40k ago .Old ones tested bad when cups went bad when I bought truck. Was told I could run all AD"s with FRX.

2) Cut open oil filter to check for metal-None which was a relief I thought. Been checked a few times out of habit with racing.

3) In tank fuel mods done with pre filter to pump- no change. Also fuel rail crossover

4) Fuel pressure-65 at idle both ports 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)- no change

6) Downloaded Torque 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 completely 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) new CPS, newest version

13) Probably need to do compression check next

14) 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.

Oh, I blew a high pressure oil line at 65 mph and if I remember right it was not too long after that the knocking started.

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



Thanks, Rob

 

Small update. The #8 intake push rod is .004 bent. Is that enough to cause a bad knock? Also, the knock coincides with the movement of the intake rocker on #8. It is just off time of the movement of the exhaust rocker so I could tell for sure it was the intake the timed perfect with knock. Lifter maybe or the push rod, or neither?

Thanks

 

Hope it ends up better than mine. I replaced a few parts chasing my knock. Finally took it for its last run when it blew out the cylinder wall on that cylinder. I found the issue with a bore scope.

 

Lots of info, thanks!

No experience with the lifters on these unfortunately, so I'm no help there. Bad lifters are not a common issue on this forum. That said it sure sounds like a valve isn't valving properly.

Given you swapped #4 and #8 with no change points to good injectors and wiring, but the cylinder is not.

Still I'd start with a buzz test and a CCT test. I'll recommend Forscan lite over Torque Pro. We are familiar with those tests, and having a number to define how badly #8 is contributing would help.

That it idled smoother with #8 disconnected is reminding me of something that I can't put my finger on atm.

 

Not really sure it was smoother idle, in fact it dropped off like the others, but the noise went away. I had a buzz and CC done a while back. I need to find the paperwork. Did it at buddies shop. I think it was 1or 3 and 8 with issues. Buzz sounded fine with no change actually. Also I thought he dropped cylinders but knock never went away. I read about the CPS with 3 and 8 so bought the newest version, dark grey with purple o-ring. back in December. Did not really see any difference though. I used the free version of Torque just because but keep having issues with it, but believe it is me and not the app.

Can .004 bend in pushrod really be that bad to cause issue.? I would think not, but don't know these engines. I build SBC's and BBC's quite often but diesels are a different breed to some extent as far as I know. I will get a new pushrod tomorrow anyway and put it in. Only the intake side was bent slightly.

 

I wouldn't think a pushrod would be the problem if it goes away when you unplug the injector. Knock staying in the same hole with different injectors make me think a little differently than injectors as much as their supplies.

You did the FRx and H&H...

Have you pulled that glow plug? Inspection camera the cylinder?
Pulled the fuel rail plug and run a gun cleaning brush thru it from #2 towards #8? Oil rail? Wondering if it had something clog up a rail in all that milage before the fuel mods.

 

Not thinking the pushrod is issue either. I will pull the GP tomorrow afternoon and see if has been hurt or anything. I don't have a camera to put in the cylinder but would be awesome if I did.
Is there a fuel plug in the front of head I could get a brush in or just the ones with the lines going in that are already being used. on the intake side I guess a flexible brush of some type? ? I will research that. It is only the one cylinder so it worries me more now that it could be a bad piston/pin etc or something. How big are the oil passages in the head?
The knock came on rather quickly. I was heading back home from the coast towing a 2000 pound max trailer and started noticing the engine getting louder. It was 4 hour trip home Figured I was losing a rod bearing so slowed down and just cruised it hoping to make it the last 2 hours home. Well, it has been several thousand miles now and still runs and not really any louder than it was that day. I figured by now it would have broken, but I do not drive it very much at all since I am still trying to figure it out. I do need to get to the race track towing the big trailer several times a year so it is still getting used. I may just buy this other truck that only has 150k on it and do an engine swap. I know I can rebuild for same or less than the other engine($3500), but easier just to do the swap. I really do want to figure this out though. Maybe get other engine and then pull this apart, fix and sell.

 

I have been chasing this for some time now and figured that would have been my fate a long time ago. Since I build engines I was hoping for a small break and then just tear down and fix. Now I have access to a low milage 7.3 I may just swap in. Fix and sell this one. Be nice to know the root cause first though.

 

Fuel rail banjo bolts install instructions below

Oil rail plugs are much larger.

This is all just a theory tho

 

A .004 bend relaxed on a table could go to .010 or .020 under load. Hopefully it's that easy but it didn't cure the knock for me. I like the bore brush idea too. I'll be giving that one a try as soon as convenient.

 

I believe @Tugly used a bore brush from a .22 rifle, but not sure.

I tagged him, so maybe he will be by shortly to share his experience with us.

 

It has been two months and my truck still sits where it was since I have been overloaded at work fixing other peoples home issues. I have not been able to get out and pull a glow plug or do compression check yet, but now need the truck for towing stuff on the job site. Any other suggestions as to where to look at items on the engine(cyl 8). Reference above, but pull injector wire and loud noise goes away and swapping injectors leaves noise in same cylinder. Going out now to pull glow plug and mess with it some. need to get compression adapter still. I am leaning towards wrist pin or piston, but who knows? I can say that a few times earlier this year when I started it cold it had zero noise till it warmed up.

 

Latest update and still need advise. I have had to do some towing for work over last week or so. Still knocking like crazy. Cold start a bit quieter then gets louder. I just ordered the compression gauge parts and should be here soon. Went out and looked at IPC and IPR numbers a few minutes ago. IPC is right at 500 but will drop to 460 at times. IPR is showing 4.6 at idle. No drive test with that though. Here is the strange part that has never happened. As I was doing the pressure check etc, the engine got quiet like it should be for about 30 seconds. No knock at all. Unfortunatly Torque was not up and running yet. It sounded great for that time. Engine was warm/hot from driving to day. It will stall on me at stops from time to time now also. HELP!!! If I had a mechanical issue why did it go away for 30 seconds. Seems to be wiring, pressure or sensor issue?

 

Have you checked your IPR, tin nut TIGHT? IIRC, Several had issues with random stalling, tin nut was loose and/or IPR was bad. You can use a can of compressed air turned upside down and spray the CO2 on the IPR. If the truck immediately starts the IPR is bad.

 

That IPR% is about half what it should be at hot idle. The ICP is normal for a stock engine w/ no tuning though. I agree on the likelihood of it being electrical issue of some kind. I've been chasing the or similar "knock" myself. I've named it the Knock Dragon, because it's a mythical beast. I've seen some minor improvements though with battery cable replacements especially going through the multiple grounds and cleaning and tightening all connections. Also recently replaced my hpo lines and fittings and have been resealing the plugged ports in both heads. I switched to copper washers instead of o-rings, but the jury is still out on it being a viable replacement. Not quite a month yet, but so far no leaks. Like everything it's a work in progress, but the answer has to be there somewhere. I intend on slaying this dragon.