A Simple and Economic Solution for Rising Oil Temps
Diesels are built to work hard. Typically, hard work raises operating temperatures. More fuel raises EGTs, and heavy towing not only gets the transmission hot, it can also raise both the coolant and oil temps. Most diesels are designed to handle these situations, but since adequate fluid cooling is one of the keys to longevity, increasing that cooling capacity is never a bad idea.
Most diesels run separate oil and transmission coolers—which are usually externally mounted—to keep temps within the normal range. Ford, on the other hand, uses a water-to-oil intercooler on both the 6.0 and 6.4L Power Strokes. This unit’s design flaw is legendary on the 6.0L, because it often leads to more expensive repairs (such as replacing both the oil cooler and EGR cooler) or worse, if coolant and oil become mixed.
In a nutshell, Ford’s oil cooler design is a square unit that rides in the valley of engine and has small passages for both the oil and coolant inside. The passages are small enough to become plugged with coolant deposits over time, and that’s when the trouble starts.
The standard diagnostic test for cooler operation is to compare the engine’s coolant temperature against the oil temperature. By factory specs, anything under 14 degrees difference, and the cooler is doing its job. Anything over 15 degrees difference, and you’ve got the start of issues with the factory oil cooler.
If you own a 6.4L Power Stroke, the fix is not simple or cheap. Due to the tight constraints of the engine compartment, you almost always have to pull the cab to get all the stuff off the top of the engine to even access the factory oil cooler. On a 6.0L, things are not quite so tight under the hood. You have a few options at this point: Replace the stock cooler and pray it won’t crap out again before you sell the truck, or swap out the factory cooler with a full external unit, complete with remote-mount oil filter.
But Bullet Proof Diesel, in Mesa, Arizona, has developed a new fix for the 6.4L that doesn’t require cab removal and retains the factory oil cooler to get the oil up to temp quicker in colder climates. Bullet Proof Diesel’s 6.4L Half Kit, as the company calls it, is a great compromise between Bullet Proof’s full oil cooler replacement system, which does away with the factory cooler entirely, and the stock fix.
The kit incorporates an external Fluidyne oil cooler that works in conjunction with the factory unit to drop temps when they start to get outside the normal range. It’s also a simple add-on insurance package for folks who tow with their trucks. The system plumbs into the stock oil cooler via the factory oil filter canister and relocates the oil filter to a much larger, fender-mounted unit with a simple screw-on, commercial-grade oil filter. According to Bullet Proof, a typical installation will add 3 to 4 more quarts of oil to the engine and drop oil temps on the average of 15 degrees, depending on the condition of the stock oil cooler.
Removing excess heat from the engine also reduces the strain on the cooling system in general. And even though the 6.4L Ford utilizes no less than seven radiator/coolers, there’s still room for one more without transferring too much heat behind it. According to Bullet Proof, the Half Kit also buys you more time before you eventually have to replace the factory oil cooler.
More importantly, Bullet Proof says the average driveway mechanic can install the kit in a few hours with hand tools. The install is made even easier with some of the most detailed instructions we’ve ever seen for an aftermarket product. Plus, Bullet Proof has tech support available if you get stuck.
Bullet Proof Diesel’s new Half Kit for the 6.4L is not only a good solution to the factory oil cooler issue, it also buys you some peace of mind with added cooling capacity when towing heavy.
Bullet Proof Diesel
4245 E. Palm Street
Mesa, AZ 85215
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By Kevin Wilson
Photography: Kevin Wilson