Hey guys,
I just bought a 2006 F350 supercab long bed 4x4 with a 6spd manual and 4:30 gears with only 102,000 miles on it.
I got a great deal on the truck but it has some "knocking" noises. The dealer said he took it to a mechanic and he thought it was piston slap not rod/main knocking. I've built a lot of motors/hotrods but am not familiar with this engine or any of the modulars at all.

The engine hour meter says it has 3900 hours and it was a construction truck and had a fifth wheel hitch at one point so i'm guessing it was used fairly hard.

The knocking is not real loud but quite noticeable. It does seem to be somewhat load and rpm sensitive.
I'm just wondering where to look with fairly low miles like this.
I just can't imagine the cylinder walls would be worn enough to cause significant piston slap.

Would excessive crankshaft play cause knocking?
What does the timing chain tensioner knocking sound like?

Any other ideas and/or what should i check first?
thanks and sorry for all the questions,

 

Read here and see if you have the same symptoms:
https://www.ford-trucks.com/forums/7...r-tapping.html
JL

 

Yeah i checked out that thread last week. I bought a stethoscope and best i can tell the sound is pretty audible at the second to last cylinder on the passenger side. Not that high up in the cylinder head. Obviously the sound was louder when listening through the freezeplug but it seemed to be in that general area.

My main concern is figuring out how serious it is, either way its getting a newer 3v or a cummins swap but i really don't want to send a rod through the block running it into town. If there is an easier cheaper fix i obviously want to go that route to put off replacing the engine right now.

 

Well, my repair would have been only $15 if I had went with my gut instinct and pulled the cam cover to check it out.
It could be one of the chain tensioners allowing the chain to "rattle", or it could possibly be crank end play from a worn thrust bearing. Hard to say unless you've torn into it to see.
JL

 

Thats what i was figuring, i don't think the noise is coming from the top end but i'll do some more poking around to see and maybe pull the covers and check.

For checking the crankshaft endplay can it be done roughly without pulling the pan? And would this cause a "knock" higher up in the motor / piston slap on those back cylinders?

 

You can check endplay with a dial indicator and a prybar using the damper as a reference. not the easiest way, but it CAN be done that way.
I dunno how much resonance that could cause-or how the noise would sound.
JL

 

Since you have a manual tranny, you can easily check if the crank endplay is causing it.

When it's at it's loudest, press on the clutch pedal until you feel resistance. This pressure from the throwout bearing SHOULD quiet the noise noticeably if it is indeed the crank endplay. The more you step on the clutch, the more it should quiet down. If it doesn't have any effect, it's probably (most likely, 99% sure) not crank endplay.

 

Well pushing in the clutch didn't seem to quiet it down, i was really hoping that was it.

Any other ideas to check out to pinpoint it, do the rods/mains normally have issues with these trucks. Would anything else be causing a piston slap sounding knock.

 

No, not normally. If the previous owner ran it low on oil, or over revved it, they might have spun a rod bearing. Being a manual-it's possible that they managed to downshift far lower than they intended to causing damage. The aluminum bearings used on modulars last virtually forever if the engine is maintained properly, but they are not forgiving if you over rev the engine, or if you fail to keep the oil changed. If you don't find anything on the top end loose, I'd check there next.
JL

 

And do check the REAL oil pressure with a real gauge. If it falls off to almost nothing when it gets warm, that's usually an indication of bad bearings, although one or two might not provide that much of a drop-off to be really noticeable.

 

Zombie thread, but I have to try...

Was this ever resolved?

I have a similar problem.