to me the VT365 isnt that bad as long as you ward off any issues before they occur..
one *HUGE* thing is dont overheat it.. there are PLASTICS in the the oil filter housing / stand pipe area which will melt st an oil temperature of 250-260 degrees.. on an older engine climbing a big long hill foot to the floor.. oil temp of 260 isnt unheard of.. you shouldnt get there but you can.. so you want to make sure your oil temp is generally staying within 10-15 degreees of the waterr temp.. if the oil temp starts spiking and does it fairly often it can indicate the oil cooler is faulty (a very common issue with these engines if coolant maint is poor)..
the EGR cooler is another issue.. if it goes bad you can send coolant into the cylinders either causing steam damage, hydrolocking and / or overheating.. iun-explained coolant loss or excessive exhaust steam is a telltale sign..
the VT365 can also suffer from head gasket issues however they generally are not turned up high enough HP or RPM to be concerned with it.. but a single or 2 even somewhat minor over-heat events can cause head gasket failures...
in my opinion my personal self wouldnt hesitate to buy one *IF* im allowed to plug into its computer and look at the event history.. Navistar computers store telltales oin overheat and oil pressure events through the life of the engine.. you can read out the last 3 or 4 of them... you need the nexiq device or a clone, (or a dealer) and the free servicemaxx J1708 software.. if I see there are several tattletale events in the ECM esp in the recent mileage / hours I would pass.. it means there may be an issue already or the events coiuld be causing engine issues to start..
you *CAN* make a VT365 as venerable as a 7.3 (T444E).. but it costs a couple grand in parts and some good mechanical skills... it is commonly called "bulletproofing".. named after a company that sells upgraded parts for the 365 called "bulletproof diesel". there are other brands, however ive only ever worked with the brand name just because a few hundred or extra grand over generic parts can easily be eaten up by a single tow / repair bill on the road..
1. EGR cooler.. it *IS* possible to EGR delete the VT365 with the "right" software.. if your state emission tests you will fail it,. an EGR cooler upgrade ot bulletproof works great!
2. Oil cooler. update the oil cooler to a bulletproof unit..
3. solve the head gasket issue befire it occurs.. esp if you plan to turn up the horsepower with a tuner or injectors.. install ARP head studs and new gaskets.. while the heads are off like magnakansas says, inspect / replace the roller lifters.. they arent that expensive and are easy to swap when the heads are off..
4. really want to be sure? have the heads worked by a shop while they are off .. checking and working any valvetrain issues.. have the injectors tested as well...
out back together and drive for a couple hundred thousand miles (assuming the bottom end isnt work out)...
do you need to do steps 3 and 4? if the engine hasnt shown any signs of head gasket issues and you are leaving it at its stock low horsepower then not likely.. I have seen this failure much more on the fords esp thiose tuned than i have on the VT365..