Motor work. Bent rods, loose lifter,

Rdnck84_03

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From what I have seen happen with gas engines, I would guess that the lifter collapsed allowing the pushrod to drop out of the socket on the rocker. Then when it came back up on the next cycle the pushrod didn't line back up and was pushing on a high spot of the rocker which usually coil binds the valve spring.

If it were mine I definitely wouldn't even think about putting it back together until I knew what the pistons and valves looked like.

James
 

Oldstock14

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what’s the root cause you are suggesting that wouldn’t happen again with a new lifter and rod?
I didn’t know if a possible stuck lifter could’ve caused the rod to bend rather than a piston hitting the valve. That’s why I was asking if it was worth it, considering my current time constraints.

Valves hitting the pistons is the main cause of bent rods. Why the pistons and valves collide will be the reason to rebuild your engine. Hoping that something unlikely caused the bent rods is a waste of time and thought. Take it apart and LOOK!
Yes dude, but as I stated, if I had time, I wouldn’t even be here asking about removal of the heads. I would just do a full rebuild. Time IS an issue here and that’s why I’m ASKING if the gamble is worth it; if a possible stuck lifter or something other than piston to valve contact could’ve caused the bent rod. Thanks for your input.
 

Oldstock14

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This is why I suggested pulling the heads off and looking at the pistons. If you run with valve and piston contact long, it could bend a piston rod. Since you said that you had a loud knocking sound, there is a possibility of internal engine damage. The shaking while the engine was running was, most likely, because it was only running fully on 7 cylinders due to the bent push rod. Can a bad lifter cause the push rod to bend? Yes if it happened to lock in the fully decompressed (extended) position. I don't know why that would happen. Lifters usually fail to open the valve far enough, not hold it open. They can also have the bushings in the roller part (in early lifters) come apart which causes a failed lifter. If it did lock fully extended, the push rod bent from the valve and piston hitting.

This perfectly answers my question. Thank you.

From what I have seen happen with gas engines, I would guess that the lifter collapsed allowing the pushrod to drop out of the socket on the rocker. Then when it came back up on the next cycle the pushrod didn't line back up and was pushing on a high spot of the rocker which usually coil binds the valve spring.

If it were mine I definitely wouldn't even think about putting it back together until I knew what the pistons and valves looked like.

James

Okay great info. I’ll be pulling heads then. Thank you for your input.
 

Oldstock14

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Just for an update:

Managed to pull the passenger head with the motor in the truck. As I’m tearing down, I realized the motor was in fact a 6.9, not 7.3. 7/16ths head bolts. Not sad about it, slightly irritated with the previous owner as he told me it was a 7.3 though. Whatever, not the end of the world. Bought the truck years ago anyway.

Pulled the head and looked at the valve that had a worn rocker, bent rod and screwed up lifter. Valve looks fine, no play in the valve. Cool. What I did fine is much more disappointing.

The pistons are pretty banged up. The one with the bad push rod and lifter, actually has two different spots on it from where the valve made contact with the piston. I assume this means either the piston pin or the rod bearings are toast. I was actually able to rotate it just a little bit. I’m just going to be pulling the whole motor and doing a rebuild I guess. I mean that’s really my only option here correct? Hopefully the crank isn’t worn to **** but the piston looking like that kind of explains the horrific knocking noise I heard the last time the truck ran. What a bummer dude. Glad I pulled the head at all of yours recommendation. Would’ve sucked big time to slap in new pushrods, lifters and rockers and then fire it up just to hear that knocking again.
 

Oldstock14

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Nero

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It's a general rule of thumb to replace piston and connecting rod when there's contact, also to replace the valve, or have head rebuilt, as easier to replace a rod than check it for trueness. In other engines, unsure about the idi, usually a damaged valve will fail and you'll be right back at square one.
Sorry to see your engine in this state
 

Oldstock14

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It's a general rule of thumb to replace piston and connecting rod when there's contact, also to replace the valve, or have head rebuilt, as easier to replace a rod than check it for trueness. In other engines, unsure about the idi, usually a damaged valve will fail and you'll be right back at square one.
Sorry to see your engine in this state
Is what it is. This is my first tear down and I’ve done worse things in my life. Learning a lot and now I’ve got an excuse to put money into it I guess.

Is it possible to replace the rods and pistons while leaving the crank in the motor? Just so that it stays timed.
 

KansasIDI

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Is what it is. This is my first tear down and I’ve done worse things in my life. Learning a lot and now I’ve got an excuse to put money into it I guess.

Is it possible to replace the rods and pistons while leaving the crank in the motor? Just so that it stays timed.
Yes they come out without the crank and I really think new ones can go in with the crank. Someone correct me if I’m wrong
 

Oldstock14

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Now what about the cylinders? Just a re-hone? All four cylinders on the passenger side look okay.
 

IDIBRONCO

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Minuteman, here's some more bad news for you. Something in that cylinder is broken. The piston's not supposed to be sitting at that angle. You may have to find another engine at least for now. I'm guessing that a hone and rering is out of the question because there's probably serious damage to that cylinder wall. Can you R&R a piston and rod with the crank in? Yes. Can you do all 8 that way? Yes.
 

Rdnck84_03

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Something in that cylinder is broken. The piston's not supposed to be sitting at that angle.
I thought something looked odd when I scanned past those pictures , I definitely see it now that you called it out.

There is no option that would allow the piston to rotate in the cylinder that are going to be a cheap fix.

James
 

Oldstock14

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Minuteman, here's some more bad news for you. Something in that cylinder is broken. The piston's not supposed to be sitting at that angle. You may have to find another engine at least for now. I'm guessing that a hone and rering is out of the question because there's probably serious damage to that cylinder wall. Can you R&R a piston and rod with the crank in? Yes. Can you do all 8 that way? Yes.

I thought something looked odd when I scanned past those pictures , I definitely see it now that you called it out.

There is no option that would allow the piston to rotate in the cylinder that are going to be a cheap fix.

James


Yeah I figured that the piston had a bad pin or rod bearing and that’s why the piston was rotatable/at an angle. Are you guys thinking the cylinder wall is torn up or something to that effect?
 

Nero

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Oh dang I didn't even notice off the get go the piston is rotated significantly.

Get the rod out and inspect it. That's some major rod twist, worn rod bearings or wrist pin won't cause it to turn that far
 

IDIBRONCO

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Get the rod out and inspect it. That's some major rod twist, worn rod bearings or wrist pin won't cause it to turn that far
. Are you guys thinking the cylinder wall is torn up or something to that effect?
Yes. The cylinder wall is probably damaged pretty badly.
It's not a rod bearing that makes the piston sit at that angle. It would have to be a twisted rod (not real likely in my opinion), Broken rod cap, broken rod, a broken piston which is the #1 guess in my opinion. The wrist pin being bent probably wouldn't cause that. It's made of thick steel while the piston is made of relatively thin aluminum. The wrist pin could bend, but not in a rotational direction. The engine wouldn't run that long. The same goes for the rod. They usually bend, not twist. In order for the wrist pin to bend, it has to make contact with the cylinder wall which is also made of hardened steel. Once that happens, you'll have a hole in the cylinder wall or at least a major crack. That would drain the coolant into the oil pan.
 
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