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Jeep has been acting up recently now that I have been running it about 250 miles a week to work. Tested the fuel system and no issues in that area. Did a compression test and came up with: 138, 128, 132, 132, 145, 100. Added a little oil to no.6 and it came up to 150 also put some air to the cyl and it's blowing up thru the dipstick. Am I looking at a rebuild or maybe get lucky and re-ring no.6?
Update: put the bore scope in the hole and didn't see anything broken. Couldn't get to see the piston toward the front of the engine though. Cylinder walls have light scratching but nothing heavy. Top of the piston looked good but still has oil on it.
 

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From your above post, it sounds like worn or damaged rings.

With all the work necessary to re-ring only one cylinder, I think you will be best advised to re-ring all 6. You're going to have to pull the head and oil pan, so why not do a complete job?

Once you have the #6 piston out, you'll need to check the remaining cylinders for round and taper. You should be able to get a good idea about 1-5 cylinder condition with the pistons still in the bore. Simply turn the crankshaft until each pair of pistons is at BDC.If they're good and simply need a hone, then proceed with replacing all your piston rings.

If the bore is out of spec, you have a decision to make.
1)- replace #6 rings with cheap rings (cheap rings should seat easier) and continue to drive the Jeep, or;
2)- rebuild the entire engine with taking the bare block to a machine shop to be bored....and on and on.

See your Factory Service manual for procedures and specs.

Good Luck, L.M.
 
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Sounds like you're due for a bottom end rebuild. I would just do it right and at the very least bore all six out and replace the rings and pistons. You'd be best off doing a complete rebuild while it's all apart.

I was looking to build my motor and the price difference was $500 between just doing a bore and new pistons vs the top end rebuild along with new bearings, cam, crank, pistons, valves.
 

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Yep assuming the quantity of oil was small as a large volume of oil will always raise CR

Could still do leak down test as weak valve springs are not uncommon but is small amount of oil raised that one sig more than the same volume of oil raised others then cylinder wall or rings


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