92 E-350 7.3 non-turbo 325k miles.......
-wondering if anyone would know what causes a cylinder to "knock", as if there's no oil in it or something.
-problem is i'm stumped....i've changed all the fluids (nothing leaking or abnormal), i've changed all the injectors, o-rings, and return lines (no fuel/air leaks), all the filters (plus fuel conditioner from ford) and still......it knocks.
-i noticed when i changed the injector where the knock seems to come from (pass. side 3rd one from front) it had a residue like rusty carbon, all the others looked somewhat consistant.
-i've only owned the vehicle a few months and don't know the history unfortunately
-any thoughts or ideas??

 

has the truck always knocked??? if it has, then i would robably say that the knocking is from when someone tried to change the glowlugs and one broke off in the hole, and then they mashed it all the way in through the hole with the new glowplug and it is now lodged on top of the piston.. i know it doesn't sound good but could be true. i'm not sure about the rusty residue, that could be a bad head gasket that lets very little water in there and one time when someone let it sit, it filled up with water and when they cranked it over, it bent a connecting rod. not good either. or maybe it could be just a lifter knocking. that is not as bad as the other stuff i mentioned but still not really good. if you crack each injector line, does the motor have the same responce to each cylinder, try this, just crack each line one at a time while it is running and see if it helps any at all. good luck

 

thanks for the reply.....i'll try cracking the fuel line nuts at the injectors, is there any way to fish a magnet down the glow plug hole to see if there's something in there? if it was a small head gasket leak, wouldn't i be losing coolant or getting white smoke out the exhaust (none of these is happening)?
i'm not sure, but the noise sounds more like its coming from the cylinder, and not the head......also i'm getting a very small amount of fuel-smelling, bluish white smoke out the exhaust.....
could i have a stuck valve possibly? i don't know enough about the mechanics of the cylinder head to know what to look for.......

 

well, it could be a stuck valve. i have seen these motors actually drop a valve and when it shoves the valve back up in the hole after its bent a little and start knocking. if you find one injector line that has no effect on the motor, leave this line loose and see if the fuel-smell is gone out of the exhaust. if this hapens, pull that valve cover off and see if you see anything fishylooking up there.... valve spring or rocker laying on top of the head, a valve gone, if nothing seems wrong. turn the motor over and watch all the valves move or just start it up and let it idle. you may get an oil shower, it shouldn't be too bad just idling. dont revv it up. it could also be a lifter ticking. a lifter ticking will sound the same speed as when you crack an injector line loose on a good cylinder. a droped valve will be 2X that fast. but you should be able to tell if it is a lifter because one valve wil not go down as far as the rest of them. you may have to pull both valve covers off to check this. just a regular glow plug tip broke off will not make smoke.has the truck always been like that? or did it start it by itself, or did it start when you did something to it.

 

it could also be a rod bearing. this noise would be a fast knock. what do you mean by knocking noise, like a loud kerthunk or just a tick? if its not very loud, it could just be normal-so to speak- and be fine like it is.

 

thanks for your great feedback........i've only had the van for about 6000 miles and it's done since i've had it. seeing that i have to do the valve cover gaskets anyhow, i'll check out any suspicious activety that could be happening......although the sound dosen't seem to be coming from the valves/cylinder head area. it's definitely not a "tap", but rather sounds like a slightly loud piston stroke. i took the van to the mechanic i bought it from and he thought it was just "piston slap" (the rings are getting worn and it bounces around a little in the cylinder-nothing to really worry about), so i'll keep my eyes and ears peeled but not lose sleep over it.
i think the smoke might be a seperate issue......it seems to smoke a little after its been running a while and is hot, and the idle gets slightly rougher. the IP is a used one off another van. what do ya think?
again, thanks for your feedback.

 

i would look at the valve bridge and the rocker bolts to see if they worked loose

 

Try shorting out each cylinder to narrow down which one is making noise. Try moving the injector to a different hole and see if the noise follows - it will be that injector. Try a compression check - that will tell you if internal problems (broken piston or valve problem). At idle, remove oil filler cap check for excessive blow by. Hope this helps. Good luck.

 

great feedback.......
looks like i have some diagnostic work to do......it may take me a couple weeks, but i'll get back to you guys with any results......
thanks again for your response.........