7.3l knock

[scratchynum1]

I know i know your all thinking fuel.

i have a 89 7.3l idi in my truck with a 5 speed
but its actaully in a 79 bronco.
ive been servicing it and taking care of it as usuall and recently came up with a problem.
about 3 months ago when i started it it knocked bad like it had no oil pressure, so i drove it right into my shop and pulled the vavle covers off but the second time i started it the knock was gone. i installed and aftermarket oil pressure guage and oil never drops below 40 psi.
about a month ago i was driving it about 300 miles from my home and goind down the road at about 45 it started slowly knocking and then progressivly got louder and louder, i shut it off had a buddy tow me home and it sat for almost a month me thinking it was junk
when i got in it recently started it up and warmed it up no knock nothing quite and even came to a nice smooth idle. then progressivly over 2 days the knock came back and then became a constant and was there every time the truck started i never drove it more than 10 miles at a time.
two days ago i tore it down thinking it had to be a lifter, replacing all the gaskets new lifters, injectors and two weeks ago an injector pump, after i put it all back together the knock is still there.
im kinda out of ideas. it sounds like uper end noise but what could it be.
i cracked the lines one by one and the sound still stays constant. the heads and block and cylinders all looked in perfect condition and even the old lifters that came out showed little or no signs of wear.

also i did run some tranny fluid through the motor trying to get sludge build up out after the first time it started knocking and have changed the oil and filter 10+ times since it started looking for flakes of metal anything.

im really at a loss here
has anyone had such odd knock before.

any help?

thanks

oh and you guys are great ive been reading posts for almost two days on here before i decded to register and post.

[cdnsarguy]

Any hint as to location up, down, front or back of engine. How about the DMFW (flywheel) known to makes noises when springs are bad or broken.......

You need an item called a "Mechanics ear" electronic listening device probably Snapon or Mack since that is the only tools the guys use.

This thing is really sensitive.... how sensitive you ask!! Ya can pinpoint the flea on a dogs back that farts.........

[farnereinar]

is it a valve tap or is it a deep thud rod knocking noise, ive seen what you were talking about, slude build up on the oil pickup screen and after warmup starves the top end of oil, took awhile to figure it out cause it would come and go, always would be fine on startup then lost power and knock bad after runing it awhile

[scratchynum1]

thanks for the responses guys
im so frustraited with this thing at this point.
to me it sounds like again valve train noise or a bad lifter no thuding
if it was a thud rod i would shut it down and shoot it,
it runs fine and the noise just gets louder with rpm and back down with rpm.
no idea as to wear in the engine but it sounds like upper end (athough i am not the best at these sounds as i work more off of vibration or lack there of, because im partialy deaf and have been since i was born)
my snap on guy comes to my shop on monday so ill try to see what i can get then,

however there was about a 10th of a inch of sludge all over the top end so i cleaned the crapola out of it,

and i will check the flywheel tommarow i havn't done so yet and i do use this truck pretty hard sometimes, its possible

thanks for the responses guys ive been dead in the water for awhile.

[scratchynum1]

oh also there is no loss of power when it knocks or not its the exact same truck, witch is frustraiting,

thanks

[91diesel]

Dont mean to highjack but..


LOL Pete!!! Is that mechanics ear pretty much a super stethoscope?

[icanfixall]

Try to find the noise by loosening an injector hard line till the motor has a miss. It sounds to me like its an injecter thats hanging open and loading the cylinder creating a "fuel knock". They do sound like a rod or main bearing knock.

[cdnsarguy]

A sensative stethescope built tough for mechanic use..........

Steelman 97170 - Engine Ear Elite - Electronic Stehoscope and Vibration Detector

[dump_truck]

Originally Posted by scratchynum1

oh also there is no loss of power when it knocks or not its the exact same truck, witch is frustraiting,

thanks

I had a 93 7.3 that did the same thing, people would look to see when a rod would stick out the block, people at work would call it chitty, chitty, bang, bang. Drove it for almost 5 years, pulled my 5th wheeler with it, never got worse. That motor is now setting on the floor. The motor I have now is so quiet it's hard to belive.

[scratchynum1]

icanfixall : ive tried that and found no response, also injectors and injector pump are less than two weeks old.

dump_truck : you never foundout what was wrong with your motor? And it kept going strong like mine? serisouly i love my and the power she prodouces and some days it runs so good it makes me drool and others i feel like im driving "chitty chitty bang bang "

thanks for all the responses guys ill be working on it today at my shop, hopefully, and ill let you know what i come accross or more like the lack there of.

[truckdrivindave]

I seen a mechanix's sethoscope, at Harbor Freight. Are they any good?. Ive got a sloppy injector on my rig somewhere, dont have a clue where it is. I am hard of hearing myself but can hear pretty good.....I wonder if that will work for me....I want to find that sloppy injector this spring and get it fixed.....

[ClassicFordGuy]

I had a knock in my 94 7.3 turbo, it had been there since I bought the truck but got worse over the course of about 8k miles. Mine was a very loud knock that would come and go at idle and while driving but would always come right back. I looked everywhere and couldn't find it, all new injectors and everything. Finaly it started missing bad one one cylinder so I pulled the motor and it tuned out the driver side rear piston was very sloppy in the cylinder and all three rings were cracked, part of the oil ring was in the oil pan. Did a complete rebuild about 3 weeks ago. Mine was the loudest right by the flywheel laying under the truck. Cracking injectors told me nothing and the old screwdriver to the ear didn't help either.

Hope yours is an easy fix and not a nightmare.

-Rob

[scratchynum1]

today was the final straw, i started it up 8 am and it ran and started great, tons of power and everything drove it about 10 yards into my shop and let it idle for about a minute and here comes the knock starting slowy but coming,

so i looked around while it was running and i couldnt' tell you anything about where it was so i gave up and decided to pull the pan,

drained the oil and it was black and only has about 10 minutes of run time on it,
and thankfully i left my self enough room when i put the motor in that i could get the pan out wihtout lifting the motor,

when the pan came off i found a fair amout of sludge and some dirt and more sludge,

looked at the pickup and thought about pulling it off and almost decided not to untill i saw somthing hanging out,

i pulled the sump and well it was intresting,

1.silicone strip about the size of a rca audio cord and about 6 inches long
2.pine needels about 4 or 5
3. silicone in a flat strip about inch in diamater

so i was pretty amazed at what had just almost fallen off of the pickup and then something else caught my eye. the pickup was dented in and pushed all the way to the mesh about an inch away from the opening,
so i began to pop the dent out witch yelded more amazing stuff,

the back of the sump was about a 10th of an inch packed with dirt/sludge i thought it was metal till it broke apart in my hand, a few more bits of slicone
and then finally

now this one could possibly be the oddest thing i could think of to find in a pan,

but a part of my glow plug connector had made its way into the sump, not the whole thing but if any of you have spade style glow plugs youll know the lock part of the connector that you push to remove the plug. ya that whole lock broken off and found complete in my sump,

I have no idea how or why or the chances of that happening are but i know that iwas impressed.

so i gave it all a good cleaning and put it all back together minus my exhaust. i haven't fired it yet but i will in the morning after i put my exhaust on and i will let you guys know what happens,

i appriciate all the responses

[scratchynum1]

frustraiton has peaked,

i put the truck all the way back together today and had about 10 minutes of beautiful humming perfect run time of my truck smooth idle great throttle response everything perfect,

then here comes the knock,

its defintaly in the top end not louder below the truck or near the tranny and i think for a fact the top end is being starved of oil,
i even poped each injector line and didn't change anything,

so
1.could it be possible fore the oil pump to get clogged like it was and lose oil volume intermittenly like my truck did,
2.if so would high rpm or maybe a lack of maintance from previous owner of the motor have caused this,
3.should i be worried about churning high rpms if i replace the oil pump,
4.i do have 4:11s in my truck so i think that if thats the cause i will be doing it again soon,
5. any other sugjestions on what the heck is going on,the motor internaly lookes beautiful and the pistons look new or replaced definatly not stock,not blowing any oil out the exhaust not really using any oil.
6.also anyone know where i can get these things
cdr lower hose that goes into the intake gasket
a replacement dipstick as those universals don't come close to being long enough
and the dipstick hold down, not the hole bracket that bolts to the valve cover but just the actual hold downt that bolts to the bracket

it would be great if somone had an extra motor lying around for parts
anyways thanks for the sugjestions
ahead of time.

[lilduke]

OK. My idea. The oil has to go through the oil cooler then filter before going to the rest of engine. If you found that junk in the pan, imagine what those passageways look like.

However, the factory pressure switch is farthest away and still reads normal? Did you also tee in there with your mechanical gauge.

My guess is a combo of the oil cooler, and some return port('s) partially clogged. Restricted volume, then starvation. Can cause sporatic symptoms.