There comes a time in every diesel engine’s life cycle when O-rings fail, fittings loosen, and internal parts wear to the point where the powerplant drops a trail of oil puddles wherever you park the truck. In addition to this—and, more importantly—performance as a whole is noticeably down when these problems arise. That’s just how things are when oil, under extremely high pressures, is the engine’s driving force.
That’s also the time when we find ourselves standing—understandably a bit dumbfounded—at the service counter of our favorite diesel-repair shop, faced with the reality that fixing typical oil leaks and getting a top-end “tune-up” comprised of remanufactured injectors, new glow plugs, and a turbocharger rebuild costs as much as the down payment you made on the truck when it was new. But it’s maintenance that can’t be avoided, at any cost.
| Ruben Villalobos of Mobile Diesel Service prepares to dive into this ’02 Ford F-250’s 7.3L Power Stroke engine, to reseal its high-pressure-oil-system, and perform the 223,000-mile powerplant’s first tune-up. The engine was becoming hard to start, leaked oil everywhere when the truck was parked, and was down on power.
Most owners of OBS and Super Duty Ford rigs powered by aged but still very relevant 7.3L Power Stroke engines bite the bullet and pay the piper to the tune of $3,500 to $4,500 for such repairs. Digging through the big V-8’s mass of hoses, pipes, and wiring harnesses to reach the origin of the oil leaks and lost performance issues is a day-long job.
Labor is a big chunk of the cost for this repair. Owners who are handy with a wrench and a good shop manual might consider tackling the repairs themselves to shave a grand off. If you are so inclined, read on to learn great tips and advice from Ruben Villalobos, one of the technicians at Mobile Diesel Service, as he points out important tasks in the do-it-yourself 7.3L top-end tune-up process.
| A puddle like this is a sure sign that a 7.3L-powered Ford Super Duty’s high-pressure oil system needs some maintenance.
| When removing the MAP sensor, unplug the wire, but DO NOT disconnect its hose, as it will usually break (from age). Just unbolt the bracket and set it aside with the harness.
| Removing the intercooler tubes is easy. However, any aftermarket cold-air-intake plumbing must be taken out to facilitate access to the turbo-related tubes on the driver side.
| The tab on top of the harness connector is pushed down to release the harness from the bracket. Then the bracket is unbolted to provide access to the passenger-side valve cover.
| Pro Tip: Keep track of where all mounting studs (for the wiring-harness bracket) are located as they are removed. Mark them so they go back in the same holes, or everything will not fit together like it should.
| When removing the valve cover, if the breather isn’t leaking, don’t remove it because its O-rings aren’t always included in the cover gasket kit.
| Special spring clips secure the wires to the injectors.
| Once the covers are off, Ruben advises paying close attention to the main glow plug, as sometimes the internal connector works loose on one end. It’s a common cause for injectors misfiring or glow plugs not heating.
| We suggest using Ford’s replacement valve-cover harnesses (bottom), along with the updated “lock” that keeps the two-piece plug secure. While NAPA has a one-piece internal connector, it doesn’t have the special retainers to keep wires from accidentally being pinched when replacing the valve covers.
| Another first-timer’s tip is to remove the oil deflectors before removing the injectors. They are very easy to break and costly to replace. The deflectors are secured with Allen-head bolts.
| Ruben uses a small, adjustable, crow’s-foot prybar to gently lift each injector while keeping the retainer pushed up toward the engine valley (upper part slides over another 8mm bolt at the top of the keeper). Note: When injectors are pulled out, oil from the high-pressure rail will drain into the cylinders. That oil must be removed before replacing the injectors or the engine will hydrolock when it is cranked.
| A bad injector O-ring (top) can cause hard-start problems, because it bleeds off pressure in the high-pressure system so none of the injectors on that bank fire as quickly as they should. Send injectors out to be checked. We replaced these high-mileage versions with new squirters from Industrial Injection.
| A slick way to quickly remove glow plugs is to use a magnet. They slide right out.
Note: This is a good time to test the plugs: while they are still in the cylinder heads and easy to access. Connect a test light to the Positive post on the battery, and then touch the probe to the top of the glow plug. The light should come on if a plug is good.
| It may not seem like a big deal, but we found that using small magnetic trays works great for keeping the hardware from each side separated.
| To remove the turbo, the glow-plug relay is disconnected and set aside. Then, the intake manifold, heater, wires, and hose clamps from the intake boots and turbo are removed. The biggest time killer is getting the up-pipe clamp removed. It’s a major pain to get to and release. Spray liberal amounts of lubricant for at least an hour before trying to get them loose (we used anti-seize on them during reinstallation).
| The heater-arm lever for the wastegate is released by pushing it toward the turbo. If this is not done, the ’charger can’t be removed. Ruben says this is one item many people forget the first time they dig into a 7.3L.
| Note the dimpled hole on the turbo where the up-pipe connects. When the up-pipe is reinstalled, its dowel pin must fit inside this indent. Failure to properly align these pieces typically results in an exhaust leak and loss of power.
| We discovered the engine’s turbo stand is also a contributor to the oil leaks, thanks to an O-ring failure. All related seals are replaced in this effort.
| We found one of the oil leaks is coming from the passenger-side high-pressure feed line, at the point where it screws into the block. All of the O-rings in this system are replaced, and all plugs—common oil-seepage points—on both sides of the engine are tested.
| 7 3l Top Reseal Oil Fee Line
| As part of the tune-up, we’re replacing the high-pressure oil sensor (PN F6TZ9F838A) and regulator (PN F81Z9C968AB) because they are now easily accessible, and they will take care of any high-pressure issues that may have been occurring.
| When replacing the regulator’s outer cover, use a dab of silicone to keep the tin retainer nut from backing off.
| The 7.3L Power Stroke is also susceptible to leaking oil from around the intake manifolds. Take the time to replace the gaskets. It’s not a fun task. But we think it’s a necessity at this stage of the game.
| It’s critical that all residual oil be removed from the cylinders before reinstalling the injectors or glow plugs. Ruben uses a special suction pump to extract most of the oil, running its ¼-inch plastic hose into the cylinders through the injector openings. In lieu of using the tool, a shop vac with a ¼-inch tube taped to its hose also works for this first stage of oil removal.
| Stage two involves putting the new injectors in and valve covers on, and then cranking the engine. Doing this forces the oil out of the glow-plug holes and against the back of the valve covers, where it then drains back into the pan. When this is complete, the valve covers are removed, glow plugs installed, and the other parts are bolted back on.
| We’re using Industrial Injection’s stock-replacement, remanufactured injectors on this engine. Ruben always uses white lithium grease to lubricate the O-rings, then he pushes down hard on the injector until it “clicks” as the O-ring seats. The bottom injector retainer bolts are torqued to 120 in-lb.
| After removing the Garrett GTP-38 turbo, we rebuilt it using a $60 kit (and a $175 billet compressor wheel) from RiffRaff Diesel. Investing the hour of time saves you about $500 (the approximate cost of buying a rebuilt aftermarket unit).
| Before bolting on the rebuilt turbo, Ruben puts anti-seize on the up-pipe’s V-band clamp to prevent it from rusting.
| A very important element of the reinstallation effort is making sure the clips are snug on the new injectors, and the plugs on the tips of the glow plugs are secure.
| We got fancy and had the intake and intercooler pipes powdercoated by Double R Powder Coating in Sutherlin, Oregon. When those pieces are in place, Ruben double-checks the torque on all of the plugs and bolts that were removed and/or replaced, wiring connectors, and all the fittings.
| There is a marked difference in performance and appearance after the job is complete. The project takes about 10 to 12 hours. But we think that’s time well spent—even for a first-timer.