what can cause a ring to break

[cpdtwo]

I have an 18hp desiel motor in which new rings and pistons were replaced in aug. now I find that the ring in one piston cracked, only the top ring nodamage to anything else. there is a small wear area on the sleeve but can that cause the damage,sleeve was reamed out prior to putting new pistons in. do I need new sleeves along with new rings or will reaming and rings do>

 

[Jimbrown]

The classic cause for broken rings in a rebuilt engine is failure to cut and remome the ridge that forms in the cylinder right at the top edge of the piston where the pistion stops its upward stroke.

 

[cpdtwo]

did remome the sleeve as best i could was wooried about doing too much. I though there was a rim nean the top all the time.
is a homer the same as reaming?

 

[cpdtwo]

how much can you ream before you nedd a new sleeve?

 

[oldmech]

The small wear is from the broken ring. Rings can brokes by missing(not enough) ring Gap cleareance. MINIMUM Gap top ring is .004 X dia.in ex Piston 3.in.Dia= .012 in. other rings dia x.003 . Check each ring in cylinder sleeve. You can hone the sleeve with a stones honer with oil for remove ALL the scrach. Good Luck! Oldmech

 

[oldmech]

The small wear is from the broken ring. Rings can brokes by missing(not enough) ring Gap cleareance. MINIMUM Gap top ring is .004 X dia.in ex Piston 3.in.Dia= .012 in. other rings dia x.003 . Check each ring in cylinder sleeve. You can hone the sleeve with a stones honer with oil for remove ALL the scrach. Good Luck! Oldmech

 

[DieselPower]

Yes, the ridge can break a piston ring. The cylinder's should have had the ridges removed with a ridge reamer and then been honed and cross hatched. Easier to just install new jug's (cylinder liners) if it's a wet sleeve engine.

As oldmech noted, improper ring gap is another cause.

Could also be the rings were installed upside down. I have seen it before, not often but it does happen.

 

[cpdtwo]

how do i know if i have to little or to much space in the ring. I'm lost at where to check. also the last time I rebuilt a motor and cut the cylinders was 30+ years and they had a cutter the would take the rim off , is that the same as using a homer now. thats all I saw in the parts store to cut the rim off

 

[DieselPower]

You install the rings in the cylinder before installing them on the piston. Slide the ring into the cylinder and measure the "gap" between the ends of the ring with a feeler gauge. If there's not enough gap they need to be filed down. If there is to much you either need the next size up in oversize rings or new liners.

 

[cpdtwo]

what would too much be?