I worked for a trucking company back in 1990. We regularly re torqued the heads and ran the overhead at 80k. A year later I moved on to a shop that dealt with series 60s. Havent worked 855s in a long time and im trying to remember or figure out where they got that information. I was young back then and just did not questioning the source of the reason. I do know in the time i was there i never saw a leaking head gasket or block deck wear at time of inframe so there has to be something to it! Do any of you know of any cummins publications or service bulletins on the subject? Trying to figure out if that was a cummins recomendation or a home brew procedure. My memory that long ago is fuzzy at best!
Not necessary, a bunch of work for nothing except running the overheads.
Everyone had their own tricks and theory’s about trying to keep head gaskets from leaking on those engines. I don’t recall any Cummins documentation on that practice.
There were several problems designed into the NTA/NT/NTC 855 Cummins engine. One big problem was bore spacing. Had Cummins added 3/4" of an inch to the deck/ length and added 1/4" between the counter bores 1 & 2 , 3 & 4, 5 & 6 it would have added much more strength to the deck. The other problem was Cummins never started using lower press fit liners till 1988 when the NT88 engines came out, after that liner/counter bore problems dropped way off. The other was water port erosion, had Cummins installed a stainless press in water port it would have stopped the erosion. And had Cummins gone to the 7 1/4" long head bolts instead of the early 6 1/4" long bolts sooner less head gasket issues would have been the result. But it was still a relatively good engine.
Dependable even as weepy, overhauled a number of them and only set head torque ONCE, never retorqued. Head leakage could end up with coolant around head bolts, hastened their corrosion and eventual breakage, replaced a number of broken head bolts prior to loosing a head gasket. Almost Always the head ear position bolts at head ends seldom from any under rocker assemblies.