When internationally-renowned explorer Gary Wescott recommended buying a used Ford with the legendary 7.3L Power Stoke Turbo Diesel in a recent interview, truck camper aficionados sat up and took notice. This is the engine Gary and Monika Wescott chose when they built The Turtle V and the powerplant they still use today. As a matter of fact, the couple’s 1999 Ford F550 came with the one millionth 7.3L Power Stroke. The bulletproof reliability of the 7.3L is well-known. But what makes purchasing a Ford with this venerable diesel even more attractive is the cost. You can buy a good Ford F350 with the 7.3L Power Stroke for about $15,000. Depending on options, today’s trucks are selling for five to six times that to say nothing of the EPA headaches associated with buying a new diesel. In this article we make a case for why a Ford F350 with 7.3L Power Stroke turbo diesel is still a great platform for truck camper rigs.
The Navistar 7.3L Power Stroke
With 2.5 million produced from 1994 to 2003, the International Navistar 7.3L Power Stroke V8 is widely regarded as one of the best diesel engines ever built. Even die-hard Cummins and Duramax enthusiasts acknowledge the 7.3’s excellence. While it’s true that the 7.3L isn’t as capable as today’s diesel engines, the beauty of the 7.3L design is its simplicity, reliability, and durability. Odometer readings between 300,000 and 500,000 are commonplace and many 7.3s have joined the 1-million-mile club. Couple the ruggedness of the 7.3L V8 with a simple yet effective emission system in late-models, and you’ve got a truck that is highly sought after by diesel first-timers and aficionados alike, and why so many 7.3s can be seen on today’s roads hauling truck campers and pulling heavy loads.
For the 7.3L Power Stroke, it all starts with a burly cast-iron block and cylinder head for extra strength and durability. For greater clamping force, Navistar engineers secured each cylinder to the block with six 12mm head bolts rather than five or four head bolts as found in the 7.3L IDI and the 6.0L Power Stroke, respectively. While the 444 cubic-inch engine shares the same bore and stroke as its 7.3L IDI predecessor, it features a direct fuel-injection system using massive Caterpillar HEUI injectors and a Garrett TP38 (1994.5 to 1997) or GTP38 (1999 to 2003) fixed geometry turbocharger. Fed through a combination of high pressure oil and a low pressure fuel, the HEUI injectors offer improved performance and better fuel economy compared to previous injection systems. On the low end, the engine produces 210 horsepower and 425 pound-feet torque (1994.5) to 275 horsepower and 525 pound-feet torque (2001-2003) on the high end with a manual transmission. Late model 7.3s have even been equipped with an air-to-air intercooler for improved performance.
When it comes to emissions, however, the 7.3L Power Stroke diesel really shines. This is because the 7.3 was designed and built before stringent EPA standards were imposed on the automobile industry. The only requirement for the 7.3L was a catalytic converter, but apparently, only manual transmission Fords had them. All of that changed around 2007, when, according to author, Jeff Reynolds, the EPA and CARB began “tightening the pollution control noose on diesel engines in order to cancel soot.” In response to these mandates to reduce NOx emissions, Ford and other auto makers developed EGR, DPF, SCR, and DEF add-ons for their diesel engines. While these add-ons effectively reduce NOx emissions, they have also proven to have a low life expectancy, are expensive to maintain, and reduce fuel mileage significantly. Needless to say, most late-model diesel problems are emissions-related, including the dreaded DEF “limp mode.” Fortunately, the 7.3L Power Stroke isn’t encumbered by any of these government-mandated regulations.
Known 7.3L Issues
While the over-engineered 7.3L Power Stroke is known for being bulletproof, there are some issues, though they are relatively minor in scope and cost. The most common problem with the 7.3 is a faulty camshaft position sensor (CPS) that can either prevent the truck for starting or causing the truck to stall. Fortunately, replacing the sensor is easy and inexpensive. Leaking turbocharger up-pipes is another common problem with the 7.3L. A leak can cause the engine to lose boost and the exhaust gas temperatures (EGTs) to increase. Other common problems of the 7.3 include a faulty injector control pressure sensor (ICP) and harness, a faulty upper valve cover harness (UVCH), a leaking plastic fuel filter housing, a faulty Injector Pressure Regulator (IPR), and a faulty exhaust back-pressure valve (EBPV). Some 7.3 owners have even gone so far as to delete the entire EBP assembly.
Associated 7.3L Transmissions
Two excellent manual transmissions were offered during the 7.3L era. The ZF-5 was offered from 1994-1997; the updated ZF-6 from 1999-2003. These manual workhorses proved more than adequate for the 7.3L. Ford also offered two four-speed automatic transmissions during this era with mixed results. More about each below:
E4OD: Available from 1994 to 1997. The E4OD 4-speed automatic marked a major shift by Ford from the hydraulic controlled technology it had used for years to computer controlled technology to shift gears. Unfortunately, the E4OD had numerous issues. It had weak seals that allowed moisture inside the case, and sometimes the gears inexplicably shifted into neutral while the vehicle was in motion. The overdrive light also had a tendency to illuminate while accompanying hard shifting or slipping.
4R100: A vastly improved version of the E4OD offered from 1999 to 2003. The 4-speed automatic resolved the aforementioned issues of the E4OD, yet even the 4R100 had its problems. Owners often had trouble getting the transmission to shift into or operate in reverse and it often failed to keep up with the increased torque output of the 7.3L. Aftermarket 4R100 versions solved the torque problem by increasing the torque capacity to 1,000 foot-pounds. Some aftermarket improvements included a high-performance shift-kit and power valve, and heavy-duty clutch. The 4R100 was replaced mid-2003 with the more capable 5R100W, which was used with the Navistar 6.0L Power Stroke.
Navistar 7.3L Power Stroke Specifications
7.3L History and Ford Body Style Changes
1994-1997: Nicknamed OBS for “old body style,” the 1980-1997 Ford F-Series are well known for their simplicity, reliability, and of course their classic, square-body styling. In 1994, the 7.3L Powerstroke Diesel engine was introduced to Ford’s F-Series lineup. The engine could be paired with either an E40D 4-Speed automatic or a ZF-5 manual transmission. In 1994 7.3L Power Stroke-equipped trucks produced 210 horsepower and 425 pound-feet of torque. In 1996, the engine’s specs were increased to 215 horsepower and 450 pound-feet of torque. In 1997, California trucks received split-shot injectors for reduced emissions and the overall performance was upped to 225 horsepower and 450 pound-feet of torque. No new trucks were offered by Ford in 1998.
1999-2003: After a one-year hiatus, 1999 marked a massive change for Ford 7.3L trucks. This is also the first year Ford began referring to the F250/F350/F450/F550 trucks as the “Super Duty,” and is the first year for the “new body style” (NBS) that most Ford enthusiasts have grown to love. In 2001, upgrades resulted in an increase to 250 horsepower and 505 pound-feet of torque for automatics and 275 horsepower and 525 pound-feet of torque on manuals. Other changes included an air-to-air intercooler, a new 4R100 automatic transmission and ZF-6 manual transmission, larger split-shot injectors, new electric lift pump, a catalytic converter for all trucks with a ZF-6 manual transmission, and a Garrett GTP38 turbocharger. Unfortunately, 2001 to 2003 trucks came with a powered metal rod as opposed to the better forged metal rod (check the VIN number to verify). The powdered metal rod has proven problematic and should not be driven over 400 horsepower.
Ford Truck Camper Options
For 7.3L era Fords, we recommend buying a truck with Ford’s Camper Package (option code 532). This option offers the highest payload ratings for both the F250 and F350. The option comes with 2,000-pound rated front leaf springs, a rear sway bar, a rear overload leaf spring, and a slide-in camper certification form. We also recommend buying a truck with Fx4 package that comes with skid plates, Rancho shock absorbers, a steering damper, and FX4 decals. For those who want to tow, option code 86R provides a factory installed Class IV conventional hitch receiver rated for 6,000 pounds carrying and 15,000 pounds weight-distributing. Conventional maximum loaded trailer weights remain at 12,500 pounds with SRW pickup models, and increase up to 13,900 pounds with DRW pickup models with a GCWR of 20,000 pounds for both.
Ford F250 Payload Ratings
One look and you’ll quickly realize that the differences in the payload ratings between 2003 Ford F250s and 2022 Ford F250s are vast. Today’s payload ratings are much higher. This isn’t a reflection on Ford, per se, but more on where the light duty truck market was at the time. In 2003, the Ford F250 featured a GVWR of 8,800 pounds, regardless of bed and cab type. The payload ratings, however, differed greatly with the highest rating topping out at nearly 2,600 pounds and the low rating at 1,560 pounds. Most of the components including the frame, however, are the same across the board and should be considered when building your rig. The Ford F250 was equipped with a front Dana 60 axle with a GAWR of 6,500 pounds and a rear Sterling 10.5 axle GAWR of 9,750 pounds. Both axles still remain in use today, a testament to their excellence. The F250 came with non limited slip and limited slip rear axles in the following ratios: 3:73, 4:10, 4:30, and 4:56. The 2003 table below is a representative sample the payload ratings of this era. Some minor differences in ratings will be noted between 1995 and 2003 trucks.
2003 Payload Ratings for Ford 7.3L F250 SD Trucks
Ford F350 Payload Ratings
In 2003, most of the one-ton SRW 2WD crew cab short-bed trucks offered a 9,900-pound GVWR with a payload rating around 3,200 pounds. Similarly, for a DRW 2WD truck, a one-ton crew cab long-bed truck offered a 11,500-pound GVWR with a payload rating about 5,000 pounds. These were respectable numbers in 2003, but pale in comparison with 2022 Ford F350 numbers, which are a good 1,000 to 2,000 pounds higher. All F350 SRW trucks were equipped with a the aforementioned Dana 60 in the front and a Sterling 10.5 in the rear, while F350 duallys came with a Dana 60 in the front and a Dana 80 rear axle with a GAWR of 11,000 pounds. The Ford F350 came with non limited slip and limited slip rear axles in the following ratios: 3:73, 4:10, 4:30, and 4:56. The 2003 table below is a representative sample the payload ratings of this era. Some minor differences in ratings will be noted between 1995 and 2003 trucks.
2003 Payload Ratings for Ford 7.3L F350 SD Trucks
Ford F450/F550 Payload Ratings
While the venerable 7.3L has proven to be a dependable workhorse, the payload ratings found in the Ford F250 and Ford F350s during the 7.3 era are found wanting. Part of this is due to hauling a massive 930-pound, 444 cubic-inch diesel, of course, but today’s trucks have compensated for that extra weight by offering trucks with higher GVWRs. As a result, we recommend upgrading what you would normally purchase by one whole class if the extra payload is needed for your build. Thus, if an Ford F350 meets your requirements in 2022, and doesn’t in 2001, we recommend buying a 7.3L F450 with a GVWR of 15,000 pounds or a F550 with a GVWR of 16,000 or 17,000 pounds instead. A single rear wheel conversion to super singles for more aggressive off-roading might also be warranted.
Before Buying a 7.3
Inspect the truck carefully before purchasing. Most of these trucks are 20 years old or older, so there will likely be problems even for a bulletproof engine. The key is to buy a truck that has the lowest number of issues. First, check underneath the engine for oil leaks. These can be something as simple as a pedestal leak or a dipstick gasket at the pan, or in our case, a leaking oil pan drain plug. Second, look for contaminated coolant in the coolant overflow reservoir. Discolored coolant could be mean a dislodged injector cup or a leaking gasket or seal. Third, check the engine oil. This will determine how well the previous owner changed the oil. A low oil level is a tell-tale sign of internal use of oil and could indicate a bad injector o-ring.
7.3L Tips and Tricks
Common sense prevails when taking care of your 7.3. Faithfully change the oil every 5,000 miles with 15-40w Rotella and use a fuel additive like Diesel Kleen to keep the injectors lubed and clean. At designated intervals, regularly change the coolant, transmission fluid, differential fluid, fuel filter, and air filter. Also let your turbo idle down for at least five minutes after hauling your camper or after towing a heavy load. Cooling the turbo down will increase its life. For emergencies, always carry a good assortment of tools, a couple of quarts of oil, coolant, a fuel filter, and an extra camshaft position sensor or two. When possible, use genuine Motorcraft parts only. Without a doubt, one of the best ways to take care of your coveted 7.3L is to buy a monitor like the Edge CTS3. Don’t rely solely on the OEM dash displays when operating your 7.3.
7.3L Aftermarket Upgrades
A quick search online will reveal vast number aftermarket accessories for Ford trucks and the Navistar 7.3L. What this means, according to Gary Wescott, is that “there are thousands of companies making products just a little better and a little stronger than what Detroit could afford to use on an assembly line vehicle. Better bearings, better brakes, better water pumps, better air filters, better turbos, better U-joints—you name it. Some company is making something better to replace something that might break on the road of adventure when you are thousands of miles from home or the nearest dealership. Take the money you save from buying a new vehicle and use it for aftermarket parts to make it better and stronger.”
Some of the better aftermarket websites for the 7.3L include riffraffdiesel.com and xtremediesel.com. The most popular upgrades for the 7.3L Power Stroke include a PHP Hydra chip for better performance, an Edge CTS3 Monitor to keep an eye on the operating temperatures and pressures, a Banks 4-inch Monster Exhaust, and a Banks Air Intake System. Upgrading the E4OD and 4R100 transmissions is popular with 7.3 owners as well. Due to the relatively low torque 525-pound-feet rating of the 4R100, be careful to not to overdo it with performance mods unless the transmission has been upgraded.
So what upgrades did Gary Wescott make to his 1999 7.3L Power Stroke over the years? A number of things, the most notable being a new ATS Aurora 3000 turbo, a Dieselsite Adrenaline high pressure oil pump, new Bosch injectors, and an Amsoil dual remote oil filtration system. He also installed a Gates water pump, an MPA Xtreme HD starter, an Airtex HD fuel pump, a K&N Performance washable air filter, a BD Diesel crank case vent filter kit, and a secondary Racor fuel filter with a clear bowl, which can be inspected daily and drained. Gary also upgraded the primary belt to a Gates HD V Belt and changed the thermostat to a Gates, and added a Dieselsite coolant filter to keep contaminants out of his Gates water pump. All coolant hoses were upgraded to Gates Green Stripe. He also had Magnaflow Performance Exhaust re-engineer his exhaust system with a flow-through muffler and custom pipes to minimize problems with deep water crossings and to provide greater clearance on the fuel tank and mud flaps. All of these upgrades can be examined in greater detail on Gary’s website.
Final Thoughts on the 7.3
We think you’ll agree that the 7.3L Power Stroke turbo diesel is a terrific option for truck camper rigs. The simplicity and reliability of the engine is legendary and equaled only by the equally capable Cummins 5.9L. While some have called the 7.3 an “underpowered dinosaur,” that moniker is neither fair nor accurate. When it was released in 1994, 210 horsepower and 425 pound-feet of torque was a solid number and was actually more powerful than anything that GM or Dodge was offering at the time. But finding a good, low-mileage Ford with a 7.3L isn’t easy. They are getting harder to find, yet they are still out there if you are willing to take the time to look for one. High-mileage Fords with the 7.3 are more common, of course, but one should only be bought if it comes with detailed maintenance and repair records. Location where the truck has lived is also important. Due to the prevalence of road salts east of the Mississippi, we recommend looking for a Super Duty 7.3L in the arid Southwest where most trucks are virtually rust-free. This is where we found our rust-free 2003 Ford F250, and where you’ll likely find yours. Sure there’s some risk going used, but with a little knowledge and help from a mechanic or knowledgeable friend, you can buy an old Ford that will provide many years of reliable service.