1995 6.5 chevy diesel

motor runs rough and blows oil out dip stick.motor was rebulit for hole in piston,could this have happened again?

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KINGPIN2 wrote:

It does not sound good. Is it ruff all the time, idle and under power? Also when it was rebuilt was the injector system, that would have cause the problem to begin with, gone through and completly rebuilt or replaced?
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NOT REAL SURE ABOUT REBUILD,THE TRUCK WAS BOUGHT AFTER REBUILD.MISSES WORST AFTER ENGINE HEATS UP
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KINGPIN2 wrote:

First thing you need to do is to check the injectors and then the pump and make sure all is well there before going any further.
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The oil blowing out of the dipstick tube indicates excessive blow-by and/or the CDR valve (maintenance item, ~$50-$65) is inoperative/malfunctioning.
Franko

REBUILD.MISSES WORST

the pump

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WE PULLED ONE OF THE HEADS OFF THIS WEEKEND NO HOLES IN PISTON BUT LOOKING DOWN AT PISTON YOU CAN SEE THE RINGS AT TOP OF HOLE BUT NOT @ BOTTOM IS THIS NORMAL
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Hello KingPin2,
I'm trying to understand what you are describing -- is the "hole" you are referring to the cylinder in the engine block? Are the rings you are referring to the piston rings on the pistons? Please be more descriptive. If all the pistons/cylinders look alike, just describe one piston/cylinder...Franko
BOTTOM IS

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I'M SORRY I WAS NOT CLEAR I'LL START AGAIN.THE ENGINE HAD A MISS AND A LOT OF BLOWBY WE WAS TOLD IT COULD HAVE A HOLE IN THE PISTON SO WE TOOK A HEAD OFF,THE RINGS I WAS TALKING ABOUT WAS ON A PISTON.WHEN YOU LOOK DOWN IN THE CYLINDER IT LOOKS LIKE YOU COULD SEE A LOT OF RING AT TOP AND NUN ON BOTTOM SIDE OF PISTON.THANKS
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There should be five piston rings -- each ring is installed in a groove on the piston. Each piston ring pushes outward to contact the cylinder wall. With the piston near/at the top of the cylinder, you should be able to clearly see the top ring and MAYBE a tiny bit of the second ring (through top ring's gap). I do not understand "...see a lot of ring at top and none on bottom side of piston.." Did you drop the oil pan to see the bottom of the piston? Franko

AND A LOT

TOOK A HEAD

DOWN IN THE

NUN ON BOTTOM

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Franko wrote:

I disagree, there should only be 3 to 5 thousandths of clearance or so between piston and cylinder bore in a tight engine. If you can clearly see the upper rings, you may have too much clearance due to improperly sized pistons in the bore which could case a LOT of blowby.
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Hey!! For once I agree with you. How 'bout that, huh?
Dave
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THANKS FOR THE REPLYS.LOOKING DOWN AT THE CYLINDER YOU SEE MORE RING AT THE TOP SIDE OF THE CYLINDER THAN YOU DO AT THE BOTTOM.THE DISTANCE AROUND THE PISTON TO THE CYLINDER IS NOT THE SAME.SOME ADVICE IS IT'S THE CDR VALVE CAUSING THE BLOW BY.SINCE I'M THIS FAR INTO IT I'M GOING TO PULL THE OTHER HEAD OFF.THANKS MICKEY D.
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KINGPIN2 wrote:

Gravity will make piston rest on the lower side of cylinder so that it not a issue. The issue is if there is too much clearance. I am wondering if someone bored or honed the cylinders and installed pistons of the incorrect size. If you can you might pull one piston and mike its OD and then mike the ID of the bore
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WELL FOR WHAT IT'S WORTH MY 6.5 DIESEL DID HAVE A CRACKED PISTON IN THE BACK HOLE ON PASS. SIDE.THANKS FOR THE INFO. MICKEY D.
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