TOW RIG REVIVAL

HOW TO READY A 7.3L WORK HORSE FOR ANOTHER 250,000 MILES

So you’ve got a quarter-million miles on your 7.3L Power Stroke and it’s time to address a few things. Do you sell the farm and trade her in on a brand-new truck, or ready the trusty workhorse for another 250,000 miles? For the owner of this ’00 F-350 dually it was an easy choice:  x the truck that’s been reliable for the last 17 years of service and keep it on the road. And not only that, tackle some preventative maintenance items and add some power while you’re at it.

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1 While it’s not necessary to pull a 7.3L engine for an injector, turbo, and clutch upgrade, it is a requirement when the factory oil pan needs to be replaced. Once the silicone had dried on the new pan, the folks at Flynn’s turned their attention to the parts that would effectively double the F-350’s power output.

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2 According to the folks at Flynn’s, this was the first time the valve covers had ever been off of the engine, and both under valve cover harnesses (UVCH) looked to be in good shape (no burnt connection points). Once the UVCHs were removed, the spades that connect to the glow plugs were pulled via needle nose pliers.

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3 Using a 5mm Allen wrench, the injector oil return spouts were broken loose and then removed. After that, the oil rail plugs were removed using a 1/8-inch Allen, along with the injector hold down bolts, which called for an 8mm socket.

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4 From there, the injectors were worked loose using a small pry bar on the hold-down plates and all eight injectors were pulled. The fact that the stock units were fitted with black O-rings confirmed they were the original units (along with a blue lead on the number 8 injector).

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5 Replacing the 253,000-mile factory injectors was a set of Unlimited Diesel Performance’s Stage 1.5 units. These injectors come with brand new, 30% larger nozzles, new Tungsten-coated plunger and barrel assemblies, fresh O-rings, are bench tested and matched as a complete set, and flow a maximum of 160cc. They are a great budget-friendly injector option for ’99-03 Super Duty owner because their full performance potential can be reached without having to upgrade the stock high-pressure oil pump or lift pump.

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6 The larger 30% over nozzle of the Stage 1.5 injector is the key difference between it and the Stage 1 offered by Unlimited Diesel Performance. The bigger nozzle provides a quicker injection rate, which allows a lower injector pulse width to be commanded in the PCM tuning. This means you can make more power over a Stage 1 injector while experiencing the same manageable exhaust gas temperatures. This makes them one of the most tow-friendly injectors on the market. And, with a higher-flowing turbocharger added to the mix (later in this article), knocking on the door of 400 rwhp is possible in a performance tune.

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7 After all O-rings were hit with a fresh coat of engine oil, the Stage 1.5 injectors were installed. The injector hold down bolts were then torqued to 10 ft-lb, followed by the oil rail plugs being threaded back into the heads.

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8 Opting to replace all eight glow plugs and the glow plug relay at this time, each plug was broken loose next. Once they were free, they were pulled up and out of the heads via magnet (shown). Prior to installing the new glow plugs, the engine would be turned over by hand, where the oil that had made it in-cylinder during the injector removal process would be forced out of the glow plug bores. Once the cylinders were oil-free, the new glow plugs were threaded into place and torqued to 15 ft-lb, the UVCHs were reinstalled, and the valve covers were bolted back on.

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9 Tackling another preventative maintenance item, the guys at Flynn’s ditched the factory exhaust backpressure valve (EBV) equipped turbo pedestal in favor of a non-EBV unit from Garrett. Pulling the valley-mounted pedestal called for the removal of four 10mm bolts.

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10 With the turbo pedestal out of the way, a leaking passenger side fuel supply line was exposed. Constantly subjected to engine vibration, this hard line (which runs from the fuel fi lter reservoir to the rear of the cylinder head) is infamous for developing a hole where it bolts to its respective mounting bracket (arrow) and leaking fuel into the lifter valley. The new Ford line (PN F81Z- 9B273-BN) that replaced it came complete with Parker sleeves pre-installed.

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11 The non-EBV turbo pedestal shown eliminates the EBV actuator (rod and spring) that’s used to open and close a butterfly valve mounted in the turbo outlet flange in order to warm the 7.3L engine up quickly in cold weather. With age, the EBV is known to leak oil, and the butterfly can also stick in the closed position.

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12 Manufactured by Garrett, the non-EBV (or “blank”) turbo pedestal is available in three versions (’94-97, early ’99, and ’99.5-03) and carries an OE part number (PN 702670-002 for the unit we needed). As you can imagine, this part’s ability to rule out a weak link keeps it in high demand in the 7.3L segment. Ours came from our friends at DieselSite.com, along with the necessary upper and lower O-rings

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12 Manufactured by Garrett, the non-EBV (or “blank”) turbo pedestal is available in three versions (’94-97, early ’99, and ’99.5-03) and carries an OE part number (PN 702670-002 for the unit we needed). As you can imagine, this part’s ability to rule out a weak link keeps it in high demand in the 7.3L segment. Ours came from our friends at DieselSite.com, along with the necessary upper and lower O-rings

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13 Because keeping an eye on EGT is essential for any modified tow rig, a pyrometer and boost gauge would be added in the cab. For the pyrometer probe, a hole was drilled and tapped at the driver side rear of the exhaust manifold. With the truck hooked to a loaded gooseneck on a daily basis, watching EGT will be vital and this is the most accurate spot to get a glimpse of the kind of heat the 7.3L will see.

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14 For clearance reasons, the engine had to be reinstalled in the truck before the turbo could be bolted into place. The next item of business was dropping the 7.3L back down in between the frame rails. Once positioned onto the motor mount studs (two per side), the motor mount nuts were tightened with an impact, securing the engine in place. It’s worth noting that the ZF-6 manual transmission was removed at this time (more on that later).

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15 A tried and true turbo option, the Garrett GTP38R was selected for the truck’s airflow needs (PN 739619-5004S). It was chosen for its direct, bolt-in nature, its ability to cool EGT considerably better than the factory turbo, and the fact that its ball bearing center cartridge provides quick spool up. The responsiveness aspect of the 38R makes it an attractive charger for trucks used to tow, not to mention trucks with manual transmissions like this one.

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16 Thanks to a 66/88mm (inducer/exducer) compressor wheel, the GTP38R outflows the factory GTP38 by 33 percent, yet provides similar drivability characteristics thanks to its ball bearing center cartridge. The GTP38R also utilizes the 10-blade design turbine wheel that provides the signature off-idle whistle the PowerMax line of Garrett turbos is known for.

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17 Accompanying the non-EBV turbo pedestal is a non-EBV turbo outlet flange (PN 451274-0005), which is free of the valve portion (butterfly) found in the factory unit. The outlet flange installs between the exhaust housing of the turbo and the downpipe for the exhaust system. This too was sourced from our friends at DieselSite.com.

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18 To solve the leaking donuts on the factory up-pipes, a bellowed up-pipe kit from Dorman Products would get the call (PN 679-005). The complete kit comes with a cast turbo collector, stainless steel driver side and passenger side up-pipes, new mounting hardware, and up-pipe gaskets. The bellowed flanges not only eliminate the failure-prone donut gaskets, they allow expansion and contraction to occur without placing any added stress on the sealing gaskets.

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19 Being that the transmission was out of the way, installing the Dorman up-pipes as a complete assembly was a seamless process. In fact, because the original up-pipe fasteners tend to break off or strip out during removal, a lot of enthusiasts opt to remove the transmission for maximum working room when performing an up-pipe replacement.

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20 Once the new up-pipes were secure, the GTP38R was installed. First it was bolted to the pedestal, followed by being clamped to the exhaust collector and then connected to the downpipe. From there, all up-pipe bolts were fully tightened.

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21 With the potential to have 400 hp and 800 lb-ft on tap at the rear wheels, the ZF-6 was in need of a clutch upgrade. Leaving nothing to chance, a 3250 street series dual disc was ordered from South Bend. The dual-disc clutch features a diaphragmstyle pressure plate with a 3,250-pound load rating, six ceramic buttons per side of each clutch disc, a solid ductile iron flywheel, and a dampened center plate to eliminate rattle. Designed to handle 650 hp, 1,300 lb-ft of torque, and good for trucks that regularly tow in excess of 15,000 pounds, the South Bend 3250 should have zero problems in this application.

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22 Custom tuning of the truck’s PCM would be provided by a Hydra Chip (made by Power Hungry Performance) and with tuning files created by Gearhead Automotive Performance. Thanks to the Hydra’s ability to house up to 15 custom tunes at a time, everything from a 250rwhp heavy tow tune to a 400rwhp all-out file will be available at the driver’s fingertips.

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23 The final order of business for this tow rig’s revival was sending the radiator out for a thorough cleaning and pressure test. After that (and with brand new coolant in the mix), the guys at Flynn’s were confident the truck would be ready for another decade-plus of trouble-free service.

With a rusting oil pan, leaky up-pipes, and a couple of tired injectors onboard, the 253,000-mile dually was dropped off at Flynn’s Shop in Alexander, Illinois, for a refresh and repower. Over the course of several days, the 7.3L engine’s general service needs were met, along with a host of performance upgrades making their way onto the truck. With larger injectors, a GTP38R turbo, Hydra chip, and a dual-disc clutch all making it into the build, the  rst-generation Super Duty was effectively transformed into a tow rig worth keeping.DW