How many hours did the big cat motors last before a rebuild?

Got around 14,000 hrs when overhauled, D339. I have seen in old cat brochures, tractors or power units getting 30,000 hrs. All depends how they are warmed up, ran and cooled down before shutting off. And use a quality oil, check air filters, clean radiator fins, coolant changes and additives.

I’m guessing you overhauled it because oil consumption was way up and power was dropping off?
I seems like the power units would always go twice as long as a tractor. Unless they were constantly ran in a very hot location.

I managed a fleet that had, 11 1967-68 yr mod 12s. I ran them to 14,000 hrs using oil samples to make the decision. Then ran them 14,000 hrs more before selling them. Every internal bearing and gear was on the verge of failure at 28,000 hrs. Lots of chrome in every box. They are probably still getting occasional use out on some ranch now.

A neighbor ran a D333A in a D6C 74A farm tractor. At 18,000 hrs, 1 piston, valve job, rings and bearings and away they went. The mechanic that was hired was known to be overly persnickety, so they probably could have gotten by without the piston change.

When the AG tractors switched over to the dry air cleaners, the expected engine life went up dramatically. I have heard or D7E, 47A's and D8 36A's regularly getting over 25,000 hrs.

I managed a fleet that had, 11 1967-68 yr mod 12s. I ran them to 14,000 hrs using oil samples to make the decision. Then ran them 14,000 hrs more before selling them. Every internal bearing and gear was on the verge of failure at 28,000 hrs. Lots of chrome in every box. They are probably still getting occasional use out on some ranch now.

Hi DrewAbt, your posts are interesting. I don't know the level of your experience so please forgive me if I post info that you already know. I have seen too many examples of old Caterpillars being abused, Rome K/G's post about starting engine abuse is one. These pages are also from the D7E Operation and Maintenance Instruction book:
[attachment=52066]IMG_0002.jpg[/attachment] [attachment=52067]IMG_0006.jpg[/attachment]
I included them because following those instructions increases the longevity of both engines. Changing the oil in the starting engine is very important and should be done often, oil is cheap compared to overhauling or replacing the pony. Shutting the pony down by turning the gas off is very important.
The most critical factor in determining when to overhaul the engine is oil pressure. The D339 is happy using some oil as long as oil pressure isn't falling off too much during the day. I saw a D7E cooled down and shut off at high idle (the turbo just loves that). When I asked the operator why he did that he said that if he idled it down any lower the oil pressure went into the red so far that he couldn't speed the engine back up! :doh:
Craig

Thanks for sharing that Craig. Gary

14K hours seem to be a common goal, that's what we figured for the D342 if nothing happened to cut it short. A couple hidden gremlins were the oil pump drive coupling could wear dangerously thin and the center main ( thrust Main) could turn with age and shut oil off to the #3 rod.

14K hours seem to be a common goal, that's what we figured for the D342 if nothing happened to cut it short. A couple hidden gremlins were the oil pump drive coupling could wear dangerously thin and the center main ( thrust Main) could turn with age and shut oil off to the #3 rod.