More than one million 6.0L Ford Power Stroke vehicles are on the road today. Despite an exceptional torque curve, an impressive power-to-weight ratio, and a surprisingly compact package size, the 365ci Navistar International-built V-8 suffered from a series of reliability and warranty issues during its short lifespan. In response, Navistar redesigned, tooled up and built the improved 6.4L version of the Power Stroke for '08-'10 Ford Super Duty trucks. As a result, pre-owned 6.0L Ford pickups are in abundant supply, and are often a few thousand dollars less than a similarly equipped diesel pickup of the same vintage from Dodge or GM. For those of us diesel enthusiasts with mechanical aptitude, the 6.0L Power Stroke is possibly the best late-model pre-owned truck value going today.

Upgrades and troubleshooting strategies for this truck are numerous. One company that specializes in all things Power Stroke is Bulletproof Diesel of Mesa, Arizona. The company's owners, brothers Ken and Gene Neal, have invested a ton of time and money into resolving problems associated with the 6.0L. As the name implies, Bulletproof Diesel products circumvent expensive repairs and costly downtime while providing the reliability that Super Duty owners expect from their trucks. We put their upgrades to the test recently on an '04 F-350 dualie. Check out what we discovered.

Diagnosing the Patient
In almost every case, 6.0L engine failures can be attributed to shortcomings in the oil cooling system. In this section, we will cover the how and why of these failures and showcase a proven solution.

1. The 6.0L Power Stroke engine has a unique oil temperature regulation system that relies on engine coolant to raise or lower oil temperature within a given operational range. The system utilizes a compact aluminum heat exchanger that is located in the front of the engine, just under the oil filter assembly. The 6.0L engine block features a void that allows the cooler to mount inside the "V" of the engine. The self-contained stacked-plate heat exchanger is highly effective when the engine is new. However, over time the narrow interior passageways can become restricted by corrosion, debris in the coolant, and casting sand left over from the manufacturing process. This picture shows a cooler that Bulletproof Diesel cut in half with a bandsaw. Despite having roughly 45,000 miles on it, this unit was compromised. Notice the discolored areas in the passageways between the fins; this is the material that creates the restriction. When this happens, coolant flow is significantly impacted. If left unchecked, this lack of coolant flow creates a domino effect that eventually leads to catastrophic engine failure.

2. To solve the coolant restriction issue, many companies offer aftermarket coolant filtration devices that mount between the engine and radiator. While these units do in fact remove contaminants from the cooling system, they do not address the corrosion issues common to aluminum heat exchangers and coolant. However, the approach Bulletproof Diesel took is different. Rather than simply filtering contaminants from the coolant, they redesigned the system so that engine coolant and oil circuits are completely separate from one another. The Bulletproof kit utilizes airflow to regulate oil temperature. Shown here, the system features an aluminum air-to-liquid cooler that mounts just behind the grille, in the front of the vehicle. The secondary benefit of this system is that it eliminates the often-troublesome OE oil filter and cooler assembly and replaces it with a patented oil transfer block, with a remotely mounted spin-on-style oil filter that offers several benefits over the factory setup. We will discuss these a little later.

3. At the heart of Bulletproof Diesel's 6.0L oil system upgrade is a trick billet aluminum transfer block. The unit completely replaces the factory cast-aluminum oil filter housing. In doing so, engine oil is redirected to the front of the vehicle where a large aluminum cooler and filter assembly further improve upon the factory design. This block is manufactured on a CNC mill to specific design tolerances established by the engineers at Bulletproof Diesel. To the best of our knowledge, nobody else offers a unit of this kind. We like the fact that the transfer block utilizes the OE gaskets and hardware to retain the assembly to the engine. Once the cab of the vehicle is free from the chassis, the installation of the transfer block is a simple bolt-on affair.

4. Here, you can see Bulletproof Diesel's ASE certified technician, Justin Aguirre, removing the turbocharger from the top of the engine. This is the first step in the process of disassembly. If the cab of the truck were still attached to the chassis, this procedure alone might take half a day to complete. Instead, Aguirre had our donor truck's engine completely stripped down to a bare block in the same time frame.