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The Legend Lives On: Rebuilding The International DT466 Engine

One of the definitions of the word legend that I came across recently was: “A person or achievement worthy of inspiring such a story; Anyone or anything whose fame promises to be enduring...”

By Roy Berndt

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There are not many of anything that you can call a Legend but the Navistar/International DT466 diesel engine has to fall into that category.

If the 466 is not enduring I don’t know what is. The fact that you can bolt almost any part from a 466 built ’78-’93 or ’94-2004 on to one another is reality and not folk lore. Try that with any other engine manufactured in the last 25 plus years and  you have a better chance of lighting striking you down crossing the street.

The Navistar DT engine family is a line of mid-range inline-6 diesel engines (Figure 1). The Legend DT 466 is a four-cycle, six-cylinder engine with 466 cubic inches of displacement. The bore and stroke are 4.59 by 4.68 inches (116.5 by 118.9 mm). The compression ratio is 16.5:1. The maximum power output is 260 horsepower at 1,900 rpm while the maximum torque output is 800 ft-lbs. at 1,400 rpm. The engine uses direct fuel-injection combustion technology and the aspiration system is turbocharged with wastegate technology and an air-to-air intercooled design. The governed engine speed is approximately 2,500 rpm.

With horsepower ratings ranging from 170 hp (130 kW) to 350 hp (260 kW), the Navistar DT engines are used primarily in medium-duty truck and bus applications, although prior to 1986 Navistar International, then known as International, the DT engine was used in farm and construction equipment.

The DT engines are of a wet-sleeve design. This means that the cylinder wall (sleeve) is a separately machined part that fits into upper counter bores for sealing at the top with O-ring housing bores cast into the engine block in the bottom. The cylinder sleeve is in direct contact with the engine coolant, hence the “wet” sleeve. These sleeves are prefinished and do not require honing after installation. They also allow for easy in-frame overhauls during service.

This design is commonplace in larger displacement diesel engines and is considered one that enhances durability because the consistent wall thickness of the sleeve allows for even heat transfer, ensuring the cylinders stay round during thermal expansion. Additionally, it gives the ability to use a hardened cylinder sleeve that is more durable and wear resistant than a softer, cast-in wall. Also, the replaceable cylinder sleeves protect the block from damage (e.g. in case of foreign objects entering the cylinder) and can easily be replaced, which enables simpler restoration to original specifications.

The 466, however, being a high production mid-range diesel, is somewhat unique in its wet-sleeve design, because nearly all the other high production mid-range engines are in-place cylinder blocks. The down side to this scenario from the reman standpoint is that wet sleeve engines will readily have “in-chassis” overhauls – the upside is that over a million of these engines have been produced in the last 25 years, and that is not counting those used in farm and construction applications during the years prior.

Cylinder Block
The 466 engine is an inline six cylinder wet sleeve block that has six upper counter bores and six lower packing areas where the rubber seal is installed. This is a deep saddle casting where the crankshaft lies completely inside the block. Piston cooling jets bolt into the main oil gallery of the block and spray oil into the bottom side of the piston for cooling of the head of the piston.

Three different blocks were used in the various iterations of the 466. The first block going was used from 1978-1982 and carried casting numbers 675500C1/C2/C3/C4. This block had 1˝ lifter bores and they were a flat lifter-style.

The second block came on the scene in 1983 and was used through 1987. It carried casting numbers 1802330C1/C2, and had 1.125˝ lifters – these were a flat lifter-style as well.

The third block, used from 1988-1993, carried casting numbers 1810739C1/1814042C1. This version also had 1.125˝ lifter bore but used roller lifters and required retainers to keep them from rotating. If needed, this third “roller” block could be backward-compatible to the flat tappet lifter engine with the 1.125˝ lifter.

Cylinder sleeve protrusion is .0035˝± .0015˝ and can be controlled by shims available in thickness of .002˝, .004˝, .010˝, .020˝ and .032˝. Upper counterbore damage can and may occur with this engine. And when its beyond wear limits it can be sleeved and repaired. The lower O-ring seal area can also be repaired, especially if damaged by cavitation (see Figure 2).