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.