12.7 Detroit 60 Series Should i or shouldnt i ? What would you do?

1.4 million on mine. It had a set of pistons, injectors and a head put on at 550,000 due to a scorched cylinder by the previous owner and I bought it at 600k when he got custody of his kids. I had the head off this summer for a head gasket and resealing the rear portion of the front cover. The bull gear was perfect (no teeth issues and the bearing was fine), so I didn't replace it. Everything looked good, so I just had it put back together to run for a couple more years. I did put in cam bearings, but that was it.
A rebuild will cost me 1800 in labor from a small shop here in Central Florida, and I supply all the parts. They do one to two engines a week on average. My friend did his replacing everything, including starter, injectors, turbo, sensors, harness, and came in at right about $10k with labor, and he bought all genuine Detroit parts. These are great engines, and I wouldn't do anything preemptive internally except rebuild it.

 

What the hell is a "bull gear"?

 

The biggest gear in the set, or in the series of gears.

 

Hands down the smartest move I ever made in 38 years of being an owner operator was when I had Penn Detroit diesel put a reman 12.7 in the truck in the avatar at 1 million miles. Now have 1.6 million on it, do almost all other maintenance myself. Never been on the hook for an unscheduled breakdown.
Preemptively do all other maintenance things if you like, but do the entire engine/clutch at once.

 

get the extra sensors that will shut your engine down. keep in the truck or replace all & keep old ones as spares. oil press, oil temp, coolant level, coolant temp. I think are the only sensors that will leave you on the side of the road on your type engine.

 

I agree replace bull gear that's my plan haven't done it yet my 01 set s60 rebuilt @ 825k now has more than that on rebuild bull gear never been done I worry goin down the road would like to change rad and clutch fan it's locked in now the plan was to do all at once but have recently done ac condenser and air to air cooler would like to do bull gear $$$2000 w labor I'm told instead of $$$4000 after failure plus tow bill etc however running an old truck always have other priorities I'm very happy though with the truck so far plan on keeping forever cost per mile very low I don't suggest throwing money at it because you never know what you may need it for however I should have changed my turbo or at least had one on board luckily I was able to backtrack 5 miles and purchase and install in 5 hrs back on road there's ways of checking things like compressor for excess oil coming out into air drier tanks etc ie drain tanks check for oil disconnect air supply from comp pour alcohol or air line cleaner conditioner reconnect run repeat 3 or 4 times then drain air tanks again should be clean check a few weeks later for oil when draining tanks I'm not a certified mechanic I learn as I go and keep my truck out of the shop as much as possible or else might as well have another truck note with the cost of labor a few things I think are well worth it air drier every 3 yrs max always have a air govenor on board replace all hoses within 4 yrs Extra belts on board check and add to antifreeze as needed ie power cool or equivalent keeping dca levels correct very inexpensive I keep an xtra belt tensioner clamps hoses air lines quick repair ends in process now of clutch fan and radiator just did 1 injector last week $180 turbo 4 was ago $868 that's how it will go till I can overhaul just drive it easy till its wound up good then hammer on it a little bit the right way without tearing it up never let the tears spin I stop and lock them in if in a parking lot hole then unlock as soon as I'm through it knock on wood reare haven't been touched w 1.8 million only been changed once after I bought it at about 1.2 about due I'd say anyway my opinion is things last a long time if you treat them right notice how many drivers grind it into gear leaving the fuel island but hey it's not their truck they won't have to pay to fix it good luck you'll see me I'm the one their cussin at cause I'm taking too long going through the parking lot then pass me up while merging on till I wind her up and blow their doors off down the road and they cuss me again !!!