Hi lild 62992
Me again,
I worked on the 71 then the 92 then the series 50 natural gas and finally the series 40 and series 60 diesels as well as Cummins, Cat and Navistar. Capped that off with a 7 year stint as an instructor for mechanics for a large municipal transit agency...with a cherry on top!
As an instructor, I ran into a couple of recurring themes time and time again. One was; "I've been doin' it this way for 30 years, boy!" To which I would sometimes point out; "Great! However you've been doin' it incorrectly, sir!"
The other popular one was, when I would ask someone why they were botching a particular procedure with such skill and grace, they would frequently respond with "well, that's how old Buck showed me". Of course, old Buck had been doin't it that way for 30 years.
My point being, make sure you are doing what's necessary for being successful, not what somebody else did a fore ya.
You most likely are adjusting the valves and timing the injectors properly but if you aren't checking and making sure the bridges are set correctly, you're boochin' the pooch. Relying on another guy or shop or factory to do that for you is not going to yield good results each and every time. No way those bridges should ever get out of adjustment but I found them that way all the time. I wonder how that happened?
You obviously care about what you're doing or you wouldn't be asking. I assume you have a service manual and do some self study. If not, get one and give it a once over. It's a far better teacher than old Buck...or me. They used to give us some good training but now days, I think they just throw you out there and expect you to swim.
20,000 hours on an engine, in my world, is a bunch. Not unheard of but that is the equivalent of over a million miles in a truck. The dirt stuff doesn't last nearly that long but on the water, maybe.
At 32 heads in a year, you guys definitely have a problem. A key phrase here would be "failure analysis".
Carbon build up from poor combustion...low operating temps?
Overloading?
Over fueling?
Weak valve springs?
Improper adjustment?
Poor exhaust routing/manifold leaks?
Inferior components?
I'm afraid I can only ask more questions. Your company would do well to get you some help, in person, figuring this out.
Good luck.