What Makes Ford's 6.4L Power Stroke One Of The Least Reliable Diesel Engines?

There's no doubt that the 6.4L Power Stroke is one of the least reliable diesel engines ever put in a pickup truck. While in some ways it was an improvement over the 6.0L Power Stroke it replaced, if at all possible, it's best to avoid certain 6.4L Power Stroke years.

Problems that plague the 6.4L Power Stroke trucks include leaking radiators, poor fuel economy, cracked pistons, exhaust system failure, and clogged oil coolers. While these issues are mostly tied to the systems surrounding the 6.4 in one way or another, there are significant problems rooted deep within the engine's design that adversely affect its reliability.

A primary concern is diesel fuel diluting crankcase oil. Oil dilution is caused by raw diesel fuel slipping past the piston rings into the crankcase. Perhaps the most alarming part is that the raw fuel is injected into the cylinder during the exhaust stroke by design to raise exhaust temperatures during regeneration of the Diesel Particulate Filter, or DPF. Frequent oil changes are the most effective way to combat the oil dilution problem.

Cracked pistons are another common problem with the 6.4L Power Stroke. This weakness also stems from the engine's design, particularly with stock pistons. If you plan to tune your 6.4L, replacing the stock pistons with stronger forged aftermarket units before there's a problem could save you money in the long run.

International Truck and Engine Corporation, previously known as Navistar, was responsible for making the Power Stroke engines used in Ford's diesel-powered pickup trucks until 2009. The diesel-engine collaboration between the two companies began even before the 1994 introduction of the legendary 7.3L Power Stroke. While the 7.3L Power Stroke is one of the best diesel engines ever built, evolving emissions standards created a need for change.

Ford and Navistar responded to the EPA's 2007 Diesel Emission Standards with the 6.4L Power Stroke for use in Ford Super Duty F-250, F-350, F-450, and F-550 trucks from 2007 through 2010 model years. By the end of 6.4L Power Stroke production, Ford had dropped Navistar as its diesel engine supplier and brought its Power Stroke design and production in-house, releasing the 6.7L Power Stroke for 2011 Super Duty trucks.

The 6.7L Power Stroke is currently available in the Ford Super Duty lineup, over 15 years after its introduction. For comparison, the 6.4L Power Stroke only lasted for three model years before Ford pulled the plug and dropped a long-time diesel engine collaborator completely.