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Old 07-07-2010, 11:42 PM   #1
Join Date: Jul 2010
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Rebuilt Motor - Spun Bearings

I just rebuilt my 4.0 1997 Wrangler, and I heard knocking so after I dropped the oil pan, I found I had a spun rod bearing, and the main bearings had significant wear. What could have caused this?

The rebuild included new the block bored .030 over, honed, line honed, new camshaft bearings, freeze plugs, crank ground, all new crank bearings, new pistons, lifters, reconditioned rods, valve job, etc. Is this something that machine shop could have done? I didn't plastiguage any of my bearings. But, they installed the crank. I did everything else.

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Old 07-08-2010, 12:36 AM   #2
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I would be very surprised if they line honed the block. It actually takes some special fixtures to be done right and there isn't a lot of demand for that for our Jeeps. Doing all that I would put in a new cam with a little more lift as it will make the engine breath a lot better & a new oil pump would be good. What did you pay to do all of that?

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Old 07-08-2010, 01:15 AM   #3
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I also installed a new oil pump, timing set, and a comp cams camshaft.

They line honed the block because, long story short, they broke my maincap, so it was replaced with a donor. It had to be linehoned because it wasn't the original.

About 2 grand parts and labor.

Still can't figure out what went wrong
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