Pulling behind other trucks

[Rig Wrench]

(01-12-2017 )Running rough Wrote:  the earlier isx engines Had a compression ratio of around 17.1, and as far as I know, did not have major premature liner block fretting issues, this became a commen problem with the first commen rail def engines the cm2250 which I am told had higher compression Pistons a smaller turbo and more back presure, there was a story going around that cummins wanted to meet the epa2010 emmisins with egr only the way navistar tryed but failed, and so without egr cummins bored the block of many isx blocks for 16 litre displacement with a thinner wall liner, however cummins had a change of heart when they seen the negitive effects of an egr only emmisins strategy, and decided that they would go with a mix of scr dpf and egr like most other engine manufacturers, however at this time they had already cast a number of overbore size blocks, (hence the different size liner outside bore diameter liner overhaul kits built in those years, I enemy think late model 871 engines had those bores and took those liners, however it proved it just was not these oversize bores that had liner fretting issues, my opinion is cummi ns simply shipped a lot of engines with not enough liner protrusion, and that the liner simply was not held tight enough and eventually got loose enough to fret and vibrate on the liner seat

I'll add to this that earlier 570 and 870 blocks seem to be of much harder material. A 871 and 2250 will tend to cut pretty easy. The older blocks do a good job of eating cutter bits much faster