The Best Diesel Engine? By far the DT 466 by International. For the Medium Duty fleet operator this engine is the most reliable of all. Pictured is the DT 466 E [electronic version]. Each injector is controlled electronically by the engine ECM and injection is actuated by high pressure oil. These injectors are HEUI [hydraulic electronic unit injector] that are reliable but typically have to be resealed if there's a fuel in the oil problem...for example.
Here I'm setting valves which is .025 for both the exhaust and intake. One of the differences with the electronic engine and the older non-electronic models is the newer engines have the intake manifold built into the valve cover so it weighs much more, making it difficult to remove. There is the Engine Control Module as well fastened to the valve cover on the driver side.
Below is an electronic unit injector that can be tested while running with a laptop for proper injection cycles.
On the International School Bus the dog house inside the cab also has to be removed to gain access to the rear cylinders. This aside the reliability of the DT 466 E and older DT 466 in my opinion is the most reliable model for a medium duty fleet operation. One characteristic with the electronic version is a very rough start up in cold weather because of the engine oil pressure feeding the high pressure system. It takes a bit of high idling to get smooth fuel injection happening.
If you can find a mechanical DT466 then you have reached diesel heaven! With no HEUI and a Bosch fuel injection system you will have very dependable power unit. I can remember in-framing these engines for $1200.00 they are very basic and easy to work on. But technology has taken over and fuel emissions are here to stay.