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2003 Ford F-250: Project Outcast Part 3

Oil Cooler Rebuild

Mike McGlothlin
Nov 1, 2012
Photographers: Mike McGlothlin
The oil used in the ’03 to ’07 Ford 6.0L Power Stroke HEUI injection systems is the hardest working petroleum in the world. As you can imagine, engine oil that’s pressurized as much as 3,600 psi gets pretty hot, and not being able to adequately control the oil’s temperature can lead to a host of engine problems. Welcome to one of the most common failure points on the 6.0L Power Stroke: the oil cooler. Specifically, the minuscule coolant passages within the oil cooler’s fluid-to-fluid heat exchanger plug up over time. And as coolant is used to cool the oil, this blockage hampers heat transfer and eventually superheats the engine oil.
Photo 2/16   |   This 6.0L Power Stroke oil cooler rebuild kit came from MKM Customs, which in addition to offering aftermarket products, keeps a host of must-have OE items on its shelves. The most common failure on factory oil coolers is due to the coolant side of the oil-to-coolant aluminum heat exchanger’s internal passages plugging up with debris. On a more catastrophic (yet rare) note, the factory oil coolers can rupture and contaminate the cooling system with oil (and vice versa).
An easy way to tell you’ve got a failing oil cooler is by comparing engine coolant temperature (ECT) and engine oil temperature (EOT) with a scan tool. As a general rule of thumb, the two temps should stay within 15 degrees of each other when the engine is up to operating temp. Needless to say, with oil temperature spiking to 230 degrees and engine coolant remaining at or near 190 degrees, it was easy to diagnose the problem on our ’03 F-250. Just like last month’s head stud install, we’re once again opting to save money and rebuild the oil cooler ourselves, as well as add a coolant filtration system to make sure it never fails again. Read on to see our oil cooler fix for Project Outcast.
Photo 3/16   |   With the turbo, alternator, fuel and oil filter reservoirs, and intake manifold out of the way, the oil cooler can be unbolted and pulled from the lifter valley. With the underside of the oil cooler submerged in oil, it’s also ideal to allow it to drain a bit before disassembly (although no matter what you do, the heat exchanger will still be full of oil until separated from the cover).
Tip of the Month
According to Ford, 9 times out of 10, EGR coolers fail as a direct result of a failing oil cooler. So if you’re still sporting the factory EGR system (our F-250 is not), you will want to look into rebuilding the oil cooler in the event you experience a failed EGR cooler.
Parts List
Total $797.15
Part: Vendor: Details: Price:
Oil cooler rebuild kit MKM Customs Ford PN 3C3Z-6A642-CA $310
Coolant filtration kit River City Diesel Keep large debris out of oil cooler $159.99
*Oil cooler adapter kit Crossroads Ford Truck Sales ’04¼ to ’07 oil filter base/cover, solid turbo oil feed tube, Ford PN 3C3Z-6881-CA $195
*Turbo oil drain tube Crossroads Ford Truck Sales Freer drain backflow for turbo oil, Ford PN 6C3Z-9T515-A $24.38
Motorcraft Premium Gold Engine Coolant Crossroads Ford Truck Sales Flushed and replaced coolant; mixed 50/50 with distilled water, Ford PN VC-7-B $55.80 (4 gallons)
Intake manifold gaskets River City Diesel Ford PN 3C3Z-9439-AA $51.98 (2)
* = not mandatory
EGR’s Effect On Engine Coolant…
Did you know Ford recommends testing the 6.0L’s coolant every 15,000 to 20,000 miles? This is because it’s used to cool exhaust gas temperature passing through the EGR cooler from as much as 1,250 degrees to roughly 350 degrees. And it only has about 20 inches of travel time to pull off this tremendous heat reduction. It goes without saying that the 6.0L is hard on coolant.
Photo 16/16   |   project Outcast Part 3 flushed Coolant
In this photo (sent in by a reader who’d just purchased an ’04 F-250), you can see what happens to coolant if it’s neglected long enough. The left-most milk jug contains a sample from the first coolant flush. From left to right, the jugs contain samples gathered from each subsequent round of flushes. After flushing the system eight times, it was finally clean. The engine was completely stock, was presumably running the original coolant, and had 83,000 miles on the odometer.


River City Diesels
East Peoria, IL 61611
MKM Customs
Crossroads Ford Truck Sales



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