A single-row timing chain has a short life; it simply stretches. A faulty or weak chain tensioner is often the primary culprit. It either gets stuck or its spring loses tension, especially when the engine is cold and oil pressure is low. This allows the chain to become loose, skip teeth, and ultimately stretch. In extreme cases, a stretched chain can be an entire link longer than it should be. Stretching eventually causes the camshaft timing to become retarded in relation to the crankshaft, leading to a host of performance problems.
High operating temperatures degrade rubber seals rapidly. Furthermore, the engine is prone to stuck piston rings and PCV valve failures, which force oil into the combustion process. The Symptoms:
There's no sugarcoating it: the EP6DT engine, particularly in its early form, . Its numerous systemic issues place it among the more problematic modern engines.
The HPFP is sensitive to fuel quality and contamination. Internal wear of its precision components (plunger, valve) leads to a drop in fuel pressure. It also has an external seal that can fail , leading to fuel leaks contaminating the engine oil with petrol, which is very damaging to bearings.