I would like to know if anyone has experienced worn wrist pins and/or pistons during a 4.0/4.6 rebuild?
And for the piston, I am referring to the wrist pin hole.
I ask because I chased the dreaded engine tapping through a process of elimination.
After disassembly it was apparent that the cam, cam bearings, and rod and main bearings were worn out.
They definately had to be making a racket.
(I had previously replaced and ruled out the other typical culprits, oil pump, lifters, timing chain, top end, etc)
My piston and piston skirt O.D. are in spec.
I never seperated the pistons from the rods either.
When handling one of the piston and rod assemblys today, I noticed that the rod slid on the wrist pin easier than on the other 7. No play can be felt, as if the wrist pin to piston hole clearance was worn.
However, when sliding the rod side to side, causing it to hit each side of the piston...it made an earily familiar clack.
Now, granted, the rod cannot contact the piston once they are in the bore and attached to the crank, but after heat expansion, the wrist pin may possibly rattle in the piston, I don't know, but That is my concern.
It will be the weekend before I can press the pistons off, then monday(or later)to measure the piston opening vs the wrist pin. I can measure on a machine and be confident of the results, good or bad.
My concern is, that as the engine heats and parts expand, the piston(s) is clackity clackin on the rod end, and giving the dreadful mystery tick.
My question is; has anyone experienced this before in a 4.0/4.6? That the wrist pins and piston hole they fit into has worn out of spec, on one or more pistons?
I dread another $500+ in parts for this engine, but I'm afraid if I don't...it's gonna clack, clack, clack as soon as it warms up.
Regardless what they measure, I'm already thinking replacement.
Thoughts?
Experiences?
Thanks

 

And, just to confirm, of course wrist pins and pistons wear, and are typically worn(even if still in spec) when an engine needs rebuilt.
What I'm asking is; is this a known 4.0/4.6 issue, even if not common? Considering that in most cases, these engines need head gaskets before 100k miles, and Alot of them need rebuilds shortly after(mine has 122k miles, and had head gaskets at some point prior to me owning it), and that in most cases rebuilding small blocks, a bottom end with new rings and bearings, in most cases can reuse the pistons and wrist pins...but this IS a Land Rover, so that argument doesn't really apply.
Somebody tell me they had a bad piston or wrist pin too, not that it's unheard of, and I might feel better, lol.

 

Mine were fine.

 

You also had no noise prior to rebuild, correct?

I want to say that these are ok, as holding the piston in one hand and connecting rod in the other(still assembled) there is zero play that can be felt.
As tight as the tolerance is, if they were out of spec, there would have to be some play/rocking movement, but there is none.
Of the one assembly that the top of the connecting rod slid left/right on the wrist pin easier than the rest, maybe it's just cleaner, less oil. That I need to hose them all off with brake cleaner and try moving them all(I'll re-oil them before they go in the engine).
I guess this bastard and all it's quirks is making me paranoid. I just want it running again so I can get on with fixing the rest ot it. But I don't want to have to pull the motor again.
Oh well, I'll measure and go from there.

 

I just broke my wrist few days ago & they’re looking to install pins.
lmk if you wind up parting yours out...

 

lol, that's funny...but not really, been there, done that, hope you heal fast.
And, no, not going to part it out, I'm too stubborn to quit and too far down the rabbit hole on this one.
Worst case, I buy a set of pistons.

 

@SundayFunday sorry to hear about the wrist I broke mine a long time ago,hope yours heals well

 

Thanks fellas. (Don’t mean to hijack thread)
found some humor here as well..
accident should have killed me. So if all I have to heal is a broken wrist- then Things will be just fine. The support is overwhelming, and the time I log learning from this site warrants a thank you. I‘m Incredibly grateful.

 

I had no play or noise in them. I did various rocking tests on the pistons, crank, etc at various stages of my rebuild and really I expected to have a sloppy engine and just live with it since it was an old $500 auction truck.

12,000 miles later this motor just feels better than ever (probably because I'm running in Sport Mode for 2020). It's tight!

You are honing your cylinder liner walls and blue-print gapping your piston rings, so you shouldn't have any wobble or clicking of your pistons against your cylinder walls or connecting rods sliding on your wrist pins because those piston rings are touching the entire circumference of your cylinders.

 

I would agree, but if I tap the top of the rod against either edge of the piston...the sound is awfully familiar.
I know it can't move there on it's own, unless followed by a loud bang and sudden death, but it just makes me wonder what happens once it's hot and spinning several thousand rpm. If the pin moves excessively inside the piston.
I think it's unlikely it's the piston(s), that the obviously bad bearings were making the noise, but this thing has me gun shy.
It sounded like a gremlin with a ball peen hammer hitting a metal work bench, but not typical piston slap(which has a kind of "hollow" sound, if that makes sense), nor did it sound like rod knock.
Kinda hard to put so much time and money in, only to pull the engine again, and wish I'de replaced the pistons.
It's no big deal for me to press the pins out, then measure everything, but at the same time think that a bad press fit should be blatently obvious.
Who knows, but I appreciate your input and encouragement.