Design and Operation of the DT466E Diesel Engine
The DT466 was introduced in 1984 as a mechanically injected powerplant for medium duty trucks, buses, generators, and agricultural equipment. In 1994 it was modified for electronic fuel injection using the HEUI (Hydraulically actuated Electronically controlled Unit Injection) system that International developed with Caterpillar. The DT466E model built from 1998 through 2003 is what I will focus on in this guide. It is a very simple and robust design and is comparatively easy to work on. Parts are readily available from both the dealer network and the aftermarket. The 2004 through 2006 EGR (Exhaust Gas Recirculation) models are similar and changes will be covered in separate sections. 1994 to 1997 models differ mostly in the location and configuration of the modules and wiring, so this guide can be used for those, too.
This manual is based on real world experience in rebuilding and repairing many of these engines. You will not find extended theory of operation but instead the focus is on that information needed to successfully build a long-running workhorse. Some of the common mechanical tasks like valve removal and replacement will not be covered and any needed information for such operations can be found online. Detailed descriptions of other things like checking liner protrusion will be covered here when they are unlikely to be easily found in other resources.
DT466E construction and design
In general specifications, the DT466E is an inline 6 cylinder turbocharged diesel with 2 valves per cylinder. A gear driven in-block camshaft operates the valves through pushtubes and roller-ended cam followers. The engine oil pump is a gerotor design located on the outside of the front cover. Its inner gear is splined to the crankshaft nose and a steel wear plate isolates the rotating gears from the aluminum front cover. The crankshaft runs in seven main bearings, and the upper rear main bearing shell incorporates a flange on each side to limit crankshaft end play. Pistons are oil-cooled by a pair of nozzles, one front and one rear, at the bottom of each cylinder.
The block is a wet liner design which is more common in large road diesels than in a medium duty truck engine. Wet cylinder liners are in direct contact with the engine coolant and are only in contact with the block at their top and bottom. This means the cylinders are cooled evenly and stay rounder at temperature, and the liners can be replaced in the field with no machine work. Liners are sealed at their bottom by an O-ring band and at the top by the head gasket. Inframe kits with new liners, matching pistons and rings, new bearing shells, and gaskets are readily available at relatively low cost.
Fuel system components
As mentioned before, HEUI injection drives the DT466E. The system uses high pressure (up to about 4000psi) engine oil to actuate the injectors. The high pressure oil pump is bolted to the back of the engine front cover and has its own reservoir fed by the engine oil pump.
A fuel/oil supply manifold bolted to the left side of the head feeds both fluids to the injectors via passages in the head. An Injector Drive Module (IDM) generates 110 volt power (48 volts in EGR motors) to open and close a spool valve atop each injector, letting pressurized oil inject the fuel. Injection timing and duration, as well as the injection control pressure made by the pump are controlled by the Engine Control Module (ECM). Both modules are enclosed in the same housing (except in the EGR model), although each has a separate connector to the engine harness.
Common DT466 problems and solutions
Common mechanical problems with these engines are leaking liner O-rings, injector failures, and occasionally broken cam follower guides. Leaking liner O-rings are sometimes seen on high mileage engines and allow coolant into the crankcase, causing high oil levels and/or steam from the crankcase breather. Extreme and sudden loss of coolant often makes the engine oil resemble grey pudding which while alarming, seldom causes engine damage as long as the vehicle is not driven extensively after discovery.
It is strongly recommend that a complete inframe be done whenever one liner has an O-ring failure; if the O-ring on one cylinder has failed it is probable that one or more others are in the same condition. Injector failure is possibly more common than in some other engines, but usually only causes a miss or a smoking issue. On pre-2004 engines injector changes are simple and do not require any valve train removal.
Broken cam follower guides are a very serious problem which is not uncommon on this engine. Since the cam followers have a roller in contact with the cam, each pair is connected by a guide to keep them from turning. If a guide breaks, the followers for that cylinder turn sideways and rapidly grind the cam lobes down. This always means a cam change no matter how quickly the problem is diagnosed. The dealer fix for preventing this issue is to install two guides on each pair of followers. It is strongly recommended to buy six extra guides and stack one on top of each existing guide whenever the head is off. This adds about $250 to the cost of each repair, but that is cheap insurance to prevent a catastrophic and costly repair down the road.
Long life and durability after a rebuild depends on several things
There are several things that are essential in rebuilding an engine if it is to have a long and reliable life. First, torque specs and tightening patterns must be rigidly adhered to, and a good quality and regularly calibrated torque wrench used. Engine assembly is no place to use an old split beam torque wrench. The pre and post 2004 engines use different head bolt torques and tightening patterns, and torque specs for engine fasteners are occasionally updated with changes.
Second, cylinder liner protrusions must be checked and must be to spec. This is possibly the single most important assembly aspect contributing to longevity. If a liner does not have enough protrusion there will not be enough crush on the head gasket fire ring and combustion pressure will not be contained. Too much protrusion although rare, could cause a coolant leak when the liner holds the head gasket off the deck. Luckily the DT466 rarely has issues here, but some factory remans with cut liner counterbores will need shims. Protrusion measurement will be covered in depth in later chapters.
Last, an original engine will nearly always have standard size bearing shells, but it still pays to look at the back of each one and make sure, then check that the bearing you are putting in is the same standard or undersize. Reman engines can easily have a reground crank and putting standard size bearing shells on a .010 undersize crank will be big trouble. Attention to detail pays off when doing this work and rushing a task, especially an unfamiliar or critical one, can have dire consequences.
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