MaxxForce DT Diesel Engine Injector Miss in a School Bus

An injector miss isn't too hard to detect since the engine code that showed up on the dash indicated a missing injector. This involved replacing the injector and a couple of seals on pressure sensors. The oil manifold is heavy and takes some work to move it on and off the top end of the engine. Once the injector is replaced and the hold down is torqued (22 ft lbs) the manifold sits on top supplying the high pressure oil from the HPOP (high pressure oil pump).

This high pressure system can get up to 4500 psi so if there are any weak spots and a leak develops the injectors stop firing properly. One test that really works well is to remove the main oil feed hose from the high pressure manifold and apply shop air to the manifold seeing if there are any leaks. If so there may be a failed seal someh where in the system.

If there are no leaks then there's a possibility of a bad IPR (injection pressure regulator) that screws into the HPOP controlling the pump output or the pump it self is not putting out pressure. Is this common? unfortunately yes we have changed out a HPOP and they are not cheap! $1700.00 while an injector runs around $500.00 which is Canadian funds. Yes it can a big owwie on the pocket book with these diesels. So I wanted to suggest something to anyone who runs MaxxForce engines.

They are bad for premature engine wear so the easiest solution is to shorten engine oil changes. We are now changing engine oil at 6000 mile (10,000 km). It's a cheap alternative compared to a premature inframe. Our fleet has had to rebuild 4 of our 2010 - 2011 DT engines due to no compression / high blow by situations. This really drives up the costs replacing pistons, liners, rings bearings, cylinder rebuild etc.

The labor on top of all this adds to the cost and down time. Another thing that would be worth going for is engine oil samples so engine conditions can be analyzed well before obvious problems occur. The results from engine oil testing covers everything from metals, fuel or coolant contamination. Well worth the cost! That's all I have to say about this subject. Leave a comments or questions below.

The Best Diesel Engine-DT 466 International School bus

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.

Cat Diesel Engine-Model 3116 installing injectors

Cat Diesel Engine injector installation on a 3116.
Before installing MUI {mechanical unit injector}injectors on a 3116 diesel engine the first thing to check is the brass sleeve in the cylinder head. It has the job of providing a seating surface for the injector, so any visible wear will require you to get the sleeves machined or replaced.

1. clean out injector sleeve bore.
2. installing o-rings on the injector tip is no longer required since the seating tool creates a seal between the injector body and seat. With the injector main body o-ring installed apply a light film of engine oil.
3. seat the injector in the bore of the head and push down firmly on the return spring until a noticeable click is heard.
4. turn injector until it engages with fuel control rack.
5. torque hold down bolt to 9 ft lbs + or - 2 ft lbs.

Use injector seating tool to seat injector into it's bore.

1. the seating tool is supplied by Caterpillar and must be used or compression may leak past injector into the fuel system.
2. re-torque injector hold down bolt when seating procedure is completed.
3. picture shows seating tool set up outside of the engine to clearly see how it works. Torque the three seating tool mounting bolts down to 20 ft lbs then seating bolt{top} to 25 ft lbs wait a few seconds then retorque.

The next step is Synchronization which I will post soon. I hope you can use this information when installing an injector on your 3116 Cat Diesel Engine