Any engine experts here? Bowed rod

[GASnBRASS]

So checking things inside my 4.0 while doing the rear main seal, it appears that the cylinder one connecting rod is bowed, perhaps 1/8" or more off center. No idea how that could have happened. Only 97K miles on the motor.

Looking at my options the easiest yet proper repair I can think of would be to remove the head, remove the pistons and rods, get a new matched rod set pressed on the pistons, have just the rod journals on the crank polished, and reassemble the engine with new rod bearings and plastigauge check the rod bearing clearances. Does this sound reasonable?

 

[Mike_H]

What makes you think the rod is bent?
If it is bent, you'll have to pull the oil pan off as well, to get the rod caps off. Then yes, the head has to come off to push the rod / piston assembly out from the top.
The wrist pin is a slip fit, no need to take it anywhere to have it pressed in. Should just be a couple spring clips that hold it in.
If your going through that much trouble I'd pull all of them, hone the cylinders, and put new rings on.

 

[cramil]

What makes you think the rod is bent?

Wondering the same? Was it running fine other than the rear main leak before? How did you determine it was bent 1/8"? Typically a bent rod is from interference with the head i.e. hit a valve or something got in the cylinder like a dropped nut into the intake etc. If there was enough impact to bend a rod you can bet that bearing and rod journal are likely damaged as well.

 

[oldb]

If you do have a bent rod, it could have been caused by a hydro lock. But you would know if you had that happen. So it would have happened to a previous owner. Does it look like the head gasket has been changed? I ran a John Deere 404 for years with a bent rod. When I went through the engine I asked the machinist to check the rods as I thought one might be bent. He said that was unlikely, I asked him to check anyway. I did have a bent rod. He asked how I knew, I told him I did not want to talk about it.

B

 

[GASnBRASS]

I've got the jeep torn apart to replace the rear main seal, think I might have removed more stuff than I needed to do the job, and I can see number 1 rod has a curve to it.
Not severe, but still not right.

 

[JeepNWilly]

wow yea I think you took removed a bit too much for rear main seal lol.
I replaced mine in my driveway just removing the oil pan and rear cap

 

[GASnBRASS]

Couple of local engine shops didn't seem to think it's an issue to just replace the one rod and bearing as long as the crank journal is still in spec and smooth. I've got the specs so I'll check the crank journal for diameter, out of round, and taper.

 

[GASnBRASS]

Had an engine shop replace the #1 rod/bearing/piston and mic the crank. Looks much worse out of the engine.

 

[StG58]

Nice picture! Wonder how the rod got bent?

 

[billiebob]

Just a bit more water would have snapped the rod and put a hole in the block.

 

[mtngoattj]

Thats what i was thinking water in the cylinder

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[bobthetj03]

Looks like the PO took er swimming.