Clogged IPR with debris in and past screen
The role of engine oil has come along way with the modernization of engine technologies. Caring for your engine used to mean that you kept enough oil in the engine, topping off now and again for the small allowance that would get burned past the rings. You would change it once in a while to prevent it from getting too thick and you would use a good name brand oil to prevent paraffin additives from sludging up. Now, engine oil is no longer just a lubricant, it is a hydraulic medium. It is a signal messenger and mover for variable valve timing, cylinder deactivation, and direct injection. Engine oil is regularly running through spool valves and actuators to run these variable components. When most mechanics think of hydraulic oil, they think of a clear liquid that turns yellowish once it is ready for a change. A stark contrast to the black burnt molasses look of engine oil at its end of life as it is drained out at proper intervals. AND, we haven’t even started talking about diesel oil; the blackest of the black. You expect that black tar looking stuff to reliably serve a hydraulic function? Crazy talk! Yet, here we are, with ever growing complexities in our modern engines and new types of problems to chase down.
Today, we are wrestling with a Ford 6.oL diesel. Not so new, 2004. This particular system has a regular old engine oil pump, pushing away at your typical 40-80psi range but it also has another pump. This pump takes that pressure and then ramps it up to over 1000 psi so that it can work on pistons inside the injectors to force diesel fuel into the pressurized cylinders of the engine. Relying on black molasses to do a hydraulic job at high pressure is exactly where things get hairy. This particular system has an oil cooler in the engine valley. Beneath which lies a metal screen with a plastic frame that inevitable deteriorates. As it does, these fragments get sucked up and churned away as that black stuff is pumped up to over a grand. It slams up against another screen designed to regulate precise pressure out to the injectors. Eventually THAT screen gives way due to plugging and pushing of the pressurized oil and debris. The result is gunk everywhere! In the pump, in the tubes, manifolds, injectors, screens… Everywhere. Being that these small pieces of gunk weren’t just politely laid in place, no, they were delivered at high pressure and crammed into their final resting place. These parts can’t be cleaned out, they must be replaced. Many many thousands of dollars later. Your truck will start.
No this is not a lemon of a design you should avoid buying, just indicative of where technology is heading and how important keeping that oil clean and of high quality is.