Just as the 7.3L Power Stroke had it's problems with o-rings both at the injectors and the external fittings, the 6.0L Power Stroke is developing it's own problematic oil control issues. To understand the significance of this article you need to understand that the HEUI (Hydraulic/Electronic Unit Injector) fuel injectors are a type of unit injectors that are actuated by high pressure engine oil. Without control of this pressure, these engines will not run.
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A failure in the low pressure engine lube oil system will cause the ICP system to starve for oil. Verifying base engine oil pressure and repairing any concerns first is a must! The minimum engine oil pressure specifications are 82.7 kPa (12 psi) at 700 rpm, 165.5 kPa (24 psi) at 1,200 rpm and 310.3 kPa (45 psi) at 1,800 rpm with the engine at operating temperature. Low or no pressure could be caused by the oil pressure regulator valve, gerotor oil pump or an internal lube oil pressure leak. If oil supply is not the cause, the ICP sensor, IPR valve, wiring and the PCM should also be checked for loose connections, damaged wiring and components and any applicable pinpoint tests should be performed to identify a failure in the control system. This is not a easy one to diagnose. The technician must first determine that there is a concern with the ICP system and typically this will show up as a continuous memory DTC. Monitoring the ICP parameter during cranking using a scan tool will verify low or no injection control pressure. The engine will not start until the PCM reads 500 psi from the ICP sensor and a low reading at this time will confirm a failure in the High Pressure Oil System. The ICP Air Leak Test is performed by applying compressed air to the system using an adapter, closing the IPR valve and listening for an audible air leak. Isolating the leak can be difficult and time consuming because all of the related components are hidden inside the engine (6.0L). Photo #1 shows an F-Series truck with the ICP sensor removed and an air line connected directly to the right high pressure oil rail. Photo #2 shows the air connected at the high pressure oil pump because accessing the ICP sensor with the test fitting and an air hose is nearly impossible and very time consuming. Using an open tubed stethoscope to listen for air noise it will be necessary to remove the oil fill tube, the oil fill plug on the left head if equipped or the engine breather on the left valve cover. Minor air leaks at the pump shaft is considered normal. If the technician is lucky the leak will be found quickly otherwise access and removal of the high pressure pump and the oil rails will be necessary to inspect all of the seals for damage. This includes the HPOP discharge fittings, injector inlet o-rings, the crankcase to cylinder head feed tubes and plugs. |
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Looking at the two photos of 6.0L injector oil inlets above, they may look similar but they are very different in their effect. The injector in Photo #3 is considered to be a full blown seal failure with the retaining ring, the backer ring and the o-ring all broken and pieces missing. This failure caused the engine to abruptly stall and it never restarted. This failure was easily located using the ICP air leak test. The injector in Photo #4 is an example of a failure in the beginning stages. This failure caused the engine not to start when it was hot due to the lower viscosity of the hot engine oil. The ICP air leak test was ineffective in detecting this leak due to it's size and the relative low pressure of the shop air. Unfortunately, both valve covers and oil rails had to be removed to inspect all 8 injector seals.
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The second common failure is the high pressure oil pump discharge quick disconnect fitting. Why this fitting is even there makes no sense. When this fitting fails to hold under pressure it separates damaging the female part of the coupling. Photo #5 shows the assembly attached to the pump. The fitting is separated and stuck in a cocked position as shown. Once apart the damage to the fitting is quite clear as you can see the fitting is elongated and the internal o-ring has come apart. This failure also resulted in the engine abruptly shutting off. The owner also reported long crank times for several days before the truck failed to restart.
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