Roughly eight years ago, the industry took note of the rocket ship nature that was a tuned 6.4L Power Stroke. With a factory compound turbocharger arrangement, a Siemens common-rail fuel system that outfl ows comparable Bosch systems by 20 percent, and a stout TorqShift transmission that can easily handle 600-rwhp, there is a lot of bang for the buck to be had in the ’08-’10 Fords. However, over time this engine has proven nearly as problematic as the 6.0L it replaced in terms of durability—and its repair costs are twice as much.

Jake Bosie of Flynn’s Shop got started by removing the upper radiator mounting brackets and the horn assembly, and then unbolted the factory fuel cooler. Instead of removing the fuel cooler completely, Bosie allowed it to rest on the front frame rail throughout the course of the install.
Although the Mishimoto radiator had already been previously installed, this is really all you need to see. On the factory 6.4L radiator, leaks begin where the plastic end tanks are crimped onto the aluminum core. As is visible here, the Mishimoto unit is 100-percent aluminum and the end tanks are TIG-welded. Added benefits of forking over the $945 for a Mishimoto radiator are that it’s a direct, drop-in replacement, features a CNC-machined, OEM-style quickdisconnect inlet and outlet, and doubles the factory coolant capacity.
With the hot-side intercooler pipe, boot, and clamp removed, Bosie disconnected the factory cold-side pipe up top and the bolts that secure it to the upper radiator support. Then, the stock intercooler was lifted out of the engine bay.
Next, Bosie disconnected the hot-side intercooler pipe from underneath the truck. According to him, the factory clamp is known to rust out and eventually break. For this install, the clamp shown would be replaced with a new springloaded, T-bolt unit supplied by Mishimoto.
To reduce front end flex and accommodate a larger diameter cold-side intercooler pipe, the customer also elected to equip the truck with Mishimoto’s upper radiator support bar. After disconnecting the hood release cable and removing the hood latch mechanism from the factory upper radiator support, Bosie pried each corner loose and pulled it off the truck.
In this comparison, you can see that the Mishimoto upper radiator support bar (bottom) offers enough clearance for a larger cold-side intercooler pipe to be used. For truck owners that retain the factory upper radiator support but want a freer-flowing, larger diameter cold-side intercooler pipe, the curved area of the factory support (top) has to be cut out in order to achieve the proper clearance.
With the factory upper radiator support removed and the stock intercooler gone, the cold-side intercooler pipe was finagled out. It would be replaced by Mishimoto’s full 3-inch diameter pipe and boot kit.

Leaking radiators, blown up-pipes, plugged oil coolers and failed emissions components can all strike (and often do) within the first 100,000 miles. Add in the fact that the OEM water separator is notorious for allowing water to infiltrate the fuel system, and you have a recipe for eventual disaster. Once water reacts with the steel fuel lines, rust forms and inevitably contaminates the injection system. In a chain reaction of events, the rust contaminants usually wreck the injection pump, which in turn sends shrapnel through the injectors. Then if you’re lucky, only the common-rail system is destroyed (not a piston or damaged cylinder), the cost of which to replace typically starts around $6,000.

After the cold-side intercooler pipe was off the engine, it was directly compared to its Mishimoto replacement. Thanks to being oblong and dented in order to clear the upper radiator support, the factory piece is extremely restrictive. Mishimoto’s mandrel-bent, 3-inch diameter, polished-aluminum pipe provides a restriction-free path from the intercooler to the engine.
To make its installation easier, Bosie attached the engine end of the Mishimoto cold-side intercooler pipe to the intake elbow first, and then set the new upper radiator support bar in place. Made of steel (vs. the thin OEM cast-aluminum piece), the Mishimoto upper radiator support bar helps isolate the front end sheet metal from frame twist. Reduced flex means less flexing of the radiator end tanks, which leads us to believe that frame twist is one of several potential culprits behind so many factory radiators springing leaks in the end tank area
Once the upper radiator support bar was tight, Bosie installed the hood latch mechanism. It’s important to note that the new upper radiator support bar may require a slight adjustment in the way the hood latches. Bosie threaded in the hood bump stops (and nuts) Mishimoto supplies with its support bar and set the correct height by opening and closing the hood several times, making height
So what makes the Mishimoto intercooler better than the factory one? For starters, it flows 20-percent more air volume than stock, lowers air intake temperature by as much as 21-percent, and provides a 50-percent reduction in pressure drop. This means reduced lag and cooler intake temps for the engine. The end tanks are cast-aluminum and are TIG-welded to an aluminum bar and plate core. By comparison, the factory end tanks are plastic, crimped on, and the core is a tube and fin design
In this photo you can see the clearance provision Mishimoto engineers into its upper radiator support bar in order to clear a larger diameter cold side intercooler pipe. Between the combination of the Mishimoto intercooler and 3-inch pipe, a 125-to-150-degree reduction in EGT can be realized at wide open throttle. A 75-degree EGT reduction is typically observed during steady-state driving
Installation of a 150-gph Titanium series FASS fuel system (PN: T F16 150G) will serve two purposes for this particular customer. First, it will provide better water separation than what the factory water separator provides (more on that in a bit), but will also ensure the K16 high-pressure fuel pump sees a consistent 8-10 psi worth of fuel pressure. While the factory frame-mounted lift pump on the 6.4L can support the stock power level just fine, with 300+ hp tuning in the mix supply pressure can drop to as low as 1 or 2 psi. Over time, the lack of adequate supply pressure can lead to highpressure fuel pump failure.
When installing the Mishimoto intercooler, Bosie took care that the lower pegs were properly seated in the grommets on the frame rail. With the new unit measuring 18-percent thicker than the stocker, it’s important to make sure it clears the transmission cooler behind it. The intercooler was secured to the upper radiator support bar courtesy of the hardware supplied by Mishimoto.
After unbolting the rear driveshaft from the differential and securing it out of the way, Bosie could better access the factory pickup on top of the fuel tank. Once the supplied fitting and fuel hose were connected to the factory suction line, Bosie looped the hose around the pickup prior to stringing it over the frame. This was done to rule out the possibility of the fuel hose becoming kinked
On the FASS system, fuel returns to the tank via this T-fi tting. After cutting a small section out of the factory fi ller tube, Bosie installed it inline, and with the (small) junction tube pointing toward the front driver side tire. Once the pump and fi lter assembly was mounted, Bosie ran the return line from the pump to the junction tube
The 100-percent bolt-on fuel system anchors to the bottom of the bed rather than the frame rail on ’08-’10 Super Duty’s. To accomplish this, FASS supplies a series of mounting plates, the smallest one being installed inside the fi rst rib in the bed. From there, the supplied L-shaped bracket is attached courtesy of a 1/2-inch Grade 8 bolt. Then the T-shaped bracket connects to the L-shaped version via four 3/8-inch Grade 8 bolts.
Once the system had been test-fi tted, Bosie got to work securing the mounting brackets to the bed and the pump and fi lter base to the T-shaped mounting bracket. This rubber spacer helps isolate the vibrations produced by the pump from transferring to the bed.
With the system mounted, Bosie cut the tank-to-pump supply hose to length, pressed it onto the supplied barbed push-lock fi tting, and then threaded it onto the 90-degree inlet fitting present in the fi lter base. It’s worth noting that FASS sends 17-feet worth of 1/2-inch diameter fuel hose with its system, which proved more than adequate for this install.
When the time came to remove the factory lift pump and water separator assembly (which Ford refers to as its horizontal fuel conditioning module), Bosie fi rst allowed it to drain for several minutes. Due to fuel coagulation, debris, a poor design, and drain interval neglect, blockage inevitably occurs and reduces the water separator’s capacity to collect water. When this happens, water is eventually passed on to the fuel system. From there, rust formation takes place, which can ultimately lead to catastrophic failure of the high-pressure fuel pump and injectors.
This supplied union fitting allows the FASS 1/2-inch supply hose to be attached on one end, while allowing the factory lift pump’s quick-connect outlet fitting to be reused on the other. The hard line that connects to the factory pump’s inlet was capped off and secured along the frame rail. The nice part about the FASS system is that fuel hose doesn’t have to be run all the way to the high-pressure fuel pump. Thanks to the 6.4L Power Stroke being equipped with 1/2-inch fuel line from the factory, some of the hard line is retained (which eases the installation process)
While wiring up the system, Bosie opted to affix heat shrink ring terminals to the power and ground ends of the wiring harness that attach to the driver side battery. Heat shrink terminals make for a water-tight, weather-proof seal and they should always be used on the wiring that powers vital components like fuel pumps
Bosie secured the supplied relay to the firewall, and in an upright fashion (to keep moisture from entering). Then the pre-wrapped wire harness was plugged in and routed out of the engine bay, along the frame rail.
During the routing of the wire harness, Bosie took care to anchor it to existing wiring and fuel lines via zip-ties. After plugging the wire harness in at the lift pump, Bosie bundled the excess present in the wire harness together and zip-tied it to the frame rail
The finished product looks like this, with the filter canisters barely being visible. Although some prefer a low-slung fuel system, Bosie and the guys at Flynn’s Shop lean toward a more concealed, clean look. In addition, the added ground clearance provided by mounting the FASS system as high as possible keeps it safer from rocks or other debris encountered on or off the pavement

In an attempt to rule out several of the latter scenarios from occurring, the owner of this 80,000-mile ’10 F-250 decided to be proactive. After dropping the truck off at Flynn’s Shop in Alexander, Illinois, it was fitted with several upgrades aimed at increasing the truck’s longevity as it ventures toward the 100,000-mile mark and beyond. For better water separation and fuel filtration, a FASS system was installed. Scrapping the leaking factory radiator, a Mishimoto replacement was bolted in its place. And finally, with the owner dead-set on running a 300hp tune, a freer-flowing Mishimoto intercooler replaced the stock unit in an effort to tame EGT. If you’re keeping your 6.4L Power Stroke for the long haul, we highly recommend you tackle these items before it’s too late.DW




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