2000 Jeep 4.0 lifter help

I have replaced a single piston with a used one on a grand Cherokee that I transferred to my wife. It had like 250k on it. Worked fine. It's got a little bit of looseness in it, as expected having 1/4 million on it, so I just used the better of the two sets of rod bearings. The only things I had to buy was an oil change and head gasket, reused everything else and did it in frame. Wouldn't necessarily recommend that route but I think I have 3 used pistons left with rod bearings. I was going to rebuild a motor to put in it for her but not now.

Oh yeah, dropping the pan is pretty easy, let the suspension drop (if it's stock height, lifted you may not need to) remove starter & you can finesse it out without touching exhaust bolts. Then look in the pan for piston pieces. If you do drop one piston in it, make sure you check on top of the ledge by the distributor for pieces. I put the ones I found back together to make sure I got all the pieces. Piston on it was not far from turning sideways in the bore and ventilating the block. Ran it 3 weeks or so before I tore into it. Figured if it was loose rod it would've come apart in that time
 
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As predicted it was indeed a broken piston. To my amazement the cylinder looks ok. There is some scoring in the very top, just below the ring ridge. I think I’m going to hone the cylinder and do as much engine work as makes sense to it as far apart as it is.
I guess my question is, what do you guys thing makes sense?
 

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As far as the cylinder repair goes, I know it needs to be honed but what about reaming the ridge? I have never done engine work like this on anything bigger than a dirt bike and I don’t have any of the tools or experience. I can watch YouTube with the best of em, but does anyone have advice for this kind of thing?
 
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ltrpilot9 said:
As far as the cylinder repair goes, I know it needs to be honed but what about reaming the ridge? I have never done engine work like this on anything bigger than a dirt bike and I don’t have any of the tools or experience. I can watch YouTube with the best of em, but does anyone have advice for this kind of thing?
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I'd knock the ridge down while you're that deep.
Look on the pass side of the block. You'll see faint colored marks at each cylinder. That color equates to the exact diameter of that cylinder. Use that as a guide for what size piston to get.
Of course, double check with proper tooling to verify.
 
Take it to a machine shop, get it measured and bored for the new pistons. You will be glad you did.
 
ltrpilot9 said:
As predicted it was indeed a broken piston. To my amazement the cylinder looks ok. There is some scoring in the very top, just below the ring ridge. I think I’m going to hone the cylinder and do as much engine work as makes sense to it as far apart as it is.
I guess my question is, what do you guys thing makes sense?
Click to expand...
which piston was it?
 
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