3406E keeps scoring pistons

did they mix up the jets when it was over hauled? they are directional. pluged oil supply for jets? or dumping to much fuel in it? ie bigger injectors than normal. thats all i can think of. one more thing didnt happen to code the injectors with a marine code-5232 or 6999.

 

Had a cummins doing the exact same thing the mechanic the used to work here just kept putting pistons in it it two broke a crank after 5 pistons I got stuck with it turned out to have little chunks of iron from the broken crank inside the oil galleys oil cooler and filter head pulled the block had it hot ranked put it back together and hasent been back since the old mechaninc never cleaned up anything pulled engine replaced crank slapped it back together just a thought

 

You may want to get a cylinder bore gauge and check the liners for roundness. A cylinder pack that has been mishandle will score, but usually takes some time for it to show up, but it will eventually, usually after a hard pull.

You may also want to make sure the water pump is moving the correct amount of coolant. CAT has had in the past a problem with the impeller slipping on the shaft.

If the injectors are defaulted to a supposed hot trim number in the ECM.......program the correct injector calibration codes from each injector into the ECM. CAT Reman injectors with defaulted injector calibration codes(trim numbers) can be as much as 20% difference in flow across the 6 cylinders. This creates a hot cylinder, but never shows up as high EGT's or coolant temperatures on the gauges, because the other 5 are hiding it by mixing the coolant and exhaust gases before the gauges sending unit. If it is a hot injector doing it on one cylinder each time...........are you paying attention to where you install them or do you throw them in nilly willy because they're defaulted to a single number? If you aren't putting the hot injector back in the same cylinder each time.......this could be why it moves to another cylinder each time it fails.

 

Seems like all that is left to check is connecting rods. Are they bent or warped?

 

Sounds like there is a Chunk of metal in the oil passage feeding the cooling jets for the Pistons. Had a JD 4WD that did the same thing to my First boss in the fall of 1994 he bought it CHEAP with a busted crank in it from the dealer and fixed it. We started Scoring Pistons the next spring and it would be a differant one every time. We solved that one by plugging all the oil cooling jet outlets but one and putting full Pressure Oil thru the system and out she popped. See not even a Hot tank will get all the crap out of a motor it might have missed something you need to blast all the passages clean be amazed WTF can get caught.

 

I agree with ironeagle2006 that you have debris stopping up the oil passage. Hot tanking want always get everything so you should go back afterwards and blow through with shop air. Best of luck finding the root cause.