Cruisin’ Down the Street in a 6.4

The 6.4L Power Stroke--A runner or something to run from?

December 2018 Tech Corner, Feature

By Jeff Dahlin from Bullet Proof Diesel

Photos By Sherm Singleton

It was big news when Ford rolled out the 6.4L Power Stroke diesel engine for 2008 model year pickups. After all, they had just been through a nightmare of problems related to the previous engine, the 6.0L Power Stoke. The 6.4L replacement was to answer those problems and eclipse the older engine in performance as well.

Well, long story short: problems remained. Follow along as we discuss some of those issues and how they can be corrected for a reliable, durable 6.4L Power Stoke.

Cooling Concerns

One problem that had plagued the previous engine was the factory oil cooler. It tended to get clogged with debris found in coolant.

Ford released an ‘improved’ version of the oil cooler and used it in the 6.4L. More stacked plates were added to help efficiency and combat plugging, but in many cases the plugging still occurred, it just took a bit longer to show up.

The aftermarket took a couple of different routes to combat this. The stock oil cooler can either be relocated to a easy-to-replace location, or it can be supplemented with an external cooler to assist with heat transfer. Bullet Proof Diesel, a company that specializes in 6.4L (and 6.0L) fixes, offers both options.

EGR Cooler/Cylinder Heads

International, who built both the 6.0L and 6.4L for Ford, aimed to solve problems related to the EGR cooler in the later engine. A separate coolant path was routed to the 6.4L’s EGR cooler instead of having it ‘downstream’ from the oil cooler, as it was in the 6.0L. This was done to prevent a clogged oil cooler from keeping coolant from the EGR cooler.

However, there are a number of situations in which coolant flow can be prevented from fully filling an EGR cooler (air bubbles, coolant leak, etc.). When this happens, it doesn’t take long for the EGR cooler to rupture.

When an EGR cooler rupture occurs, coolant can be sucked into the portion of the exhaust gas being routed back to the combustion chamber. At this point, a hydro-lock situation or blown head gaskets can result, leading to damaged engine components and expensive repairs.

One way 6.4L owners have battled this phenomenon is to use head studs, such as those produced by ARP, and upgraded, tubed EGR coolers.

Head studs, which are threaded at both ends and utilize a nut for tightening, provide more clamping force than bolts.

This helps keep the head gasket seal intact. The 6.4L uses two EGR coolers, and upgraded versions are also available from Bullet Proof Diesel and others.

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