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starting my 12v build after cylinder 6 ring failure
So long story short my ole' reliable 96 12v developed a significant tick/knock while pulling my not so heavy boat up a grade. coolant at 170 20psi boost 1100 egt and out of the blue a small noise became loud by the top of the hill . When I stopped, the engine stalled and felt as though it was trying to seize. hopped out checked the fluids, all looked well, and then she reluctantly started up again, when i hopped back out my 180k engine now had a lot of blowby that was not present before. ffrom this point on the motor had a consistant knock that fluctuated with rpm and did not change much with load. I limped her home about 30 miles, parked for about 6 months, drove her another 10 miles to my shop. dropped the NV hoping my clutch pack had busted somthing and was making the noise but no luck. Then I pulled the engine. Made a side mount out of some 3/8 plate, got it on the stand, pulled the head and my suspicion was verified. cylinder six was the issue, the piston skirt has scraped away my beautiful crosshatching from the sides perpendicular to the crank. dropped the pan and pulled the piston today. The lower compression ring is seized in its groove and seems to be the root of the problem. the piston took more damage than the cylinder luckily. So far I have only taken some quick measurements but its looking like I could get away with a new piston, rings and a good hone. all the bores are near 4.016 and the wear on cylinder 6 is less than .001 out of round. you can barely feel the scratches. I had already planned on pulling the engine to reseal and build her up for a hopefully reliable 500hp daily driver, So my current dilemma is how far I should go on the short block. I'm leaning towards just honing and replacing one piston and mains/rod bearings and oil pump, I considered replacing all the rings but i'm not sure it would be worth the risk of them not seating. Im definitely going to get the block and head checked at the machine shop for bore, out of round, taper, warpage etc, but assuming everything is within spec i'm leaning towards saving the money and not doing a full rebuild. I'd appreciate any advice or thoughts you guys have at this point, there is certainly more to come but I plan on getting the bottom end squared away first.
12-18-2017, 09:27 PM
starting my 12v build after cylinder 6 ring failure
. When I stopped, the engine stalled and felt as though it was trying to seize. hopped out checked the fluids, all looked well, and then she reluctantly started up again, when i hopped back out my 180k engine now had a lot of blowby that was not present before. ffrom this point on the motor had a consistant knock that fluctuated with rpm and did not change much with load. I limped her home about 30 miles, parked for about 6 months, drove her another 10 miles to my shop. dropped the NV hoping my clutch pack had busted somthing and was making the noise but no luck. Then I pulled the engine. Made a side mount out of some 3/8 plate, got it on the stand, pulled the head and my suspicion was verified. cylinder six was the issue, the piston skirt has scraped away my beautiful crosshatching from the sides perpendicular to the crank. dropped the pan and pulled the piston today. The lower compression ring is seized in its groove and seems to be the root of the problem. the piston took more damage than the cylinder luckily. So far I have only taken some quick measurements but its looking like I could get away with a new piston, rings and a good hone. all the bores are near 4.016 and the wear on cylinder 6 is less than .001 out of round. you can barely feel the scratches. I had already planned on pulling the engine to reseal and build her up for a hopefully reliable 500hp daily driver, So my current dilemma is how far I should go on the short block. I'm leaning towards just honing and replacing one piston and mains/rod bearings and oil pump, I considered replacing all the rings but i'm not sure it would be worth the risk of them not seating. Im definitely going to get the block and head checked at the machine shop for bore, out of round, taper, warpage etc, but assuming everything is within spec i'm leaning towards saving the money and not doing a full rebuild. I'd appreciate any advice or thoughts you guys have at this point, there is certainly more to come but I plan on getting the bottom end squared away first. 
