Mastering the 7.3L Power Stroke: Key Tech Tips for Longevity and Efficiency

Tech Tips

The 7.3L Power Stroke diesel engine used in the 1994.5-2003 Ford trucks has never been known as a real powerhouse, especially by today’s standards. But with 2-3 million of them sold, even twenty years after it last rolled off an assembly line, you’ll still find them by the dozens in everyday traffic. Whether it’s some old guy that just can’t seem to part with the one he bought new, the local landscaper that picked a couple up for his crews to load down with equipment and beat the tar out of, or its some young and upcoming diesel enthusiast that found one cheap to start learning how to mechanic on, it’s still a very solid, reliable, and somewhat capable platform to own.

The 7.3L Power Stroke has always been a solid engine platform, reliable and consistent. With that said, they aren’t without their problems. One of the more common issues with 7.3L diesel is oi leaks, like from the dipstick tube. The factory design over time will residually leak and be nearly impossible to seal, regardless of how much silicone you slather on there. But the aftermarket has the answer with a billet dipstick adapter. We’ll also be replacing the starter while we’re there.

Strictly Diesel prides itself in providing simple solutions for complicated problems and their unique billet dipstick adapter for the 7.3L Power Stroke is one of those products. Developed out of frustration of pesky oil leaks that just never went away, their dipstick adapter uses a dual O-ring seal on the outside of the pan to prevent oil leaks better than the Ford engineers ever could. The billet machined piece is easy to install and can be done in just 30-45 minutes during your regular maintenance oil change.

If you own one of these older Ford diesel trucks and just keep driving it, even though you know it doesn’t run quite like it used to or you’re tired of the leaky messes it’s leaving out in front of your house, these simple little tech tips and upgrades can go a long ways without breaking the bank or requiring a full weekends worth of cuss words and thrown wrenches to fix. The specific truck we’re working with here is a 1996 F250 with 145,000 miles that was just purchased from the original owner who had left it sitting next to the house basically forgotten about for a few years. While in overall decent condition, it’s showing its age, has the normal amount of rust where you’d expect it, but fired right up and drives decent all things considered. The original owner had it converted to a dually at the Ford dealer before he picked it up new (Ford never offered a 4×4 dually in the 1994-1997 trucks) but otherwise he never touched a thing. Still running the factory airbox, exhaust and what appears to be all original parts just about everywhere, right down to the shocks.

With the factory dipstick pulled out of the way you can start with removal of the factory adapter. Make note of the orientation of the dipstick, some are clocked straight up and down, some will tilt slightly forward. And do the best you can with some brake clean and a rag to get the debris removed so it’s not falling inside the pan upon removal.

To get access to swap this adapter out, the starter needs to be removed, making it the perfect time to replace/upgrade it while it’s off. This one is the original with 27 years of life on it, so we won’t be bolting it back on. Obviously, you’ll want to be sure the batteries are disconnected before you start working on the starter.

One of the biggest complaints you’ll hear from someone that owns a 7.3L Power Stroke, aside from how loud they are when you’re trying to order your favorite burger at a drive through, has got to be its incessant need to leak oil. When talking 7.3’s, that old saying comes to mind, “If ain’t got no oil under it, it ain’t got no oil in it.” The big Power Stroke relied on a HEUI injection system (hydraulic electronic unit injector), so high pressure oil feeds oi rails that pressurize the injectors to open/close as commanded by the trucks computer. That high pressure oil system means lots of oil fittings, oil lines, and pressures can reach as high as 3200-psi. While it’s common for some of those parts to fail and leak, one place just about every 7.3L always leaks from is the oil pan dipstick tube fitting. Ford’s design leaves a lot to be desired and over time will just allow a constant residual leak to plaque you until the truck or you reach their death.

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Using a large adjustable end wrench, pipe wrench or just about anything you can get over the large nut on the factory dipstick adapter you can start to loosen the nut for removal. In some cases you’ll find this is barely finger tight. Before the nut comes off completely, pay close attention as you’ll want to grab the internal piece with some locking pliers so it won’t drop right into the pan. You’ll need to use a small pick tool to remove the original O-ring from inside the pan so it doesn’t fall down into the engine pan where it would risk restricting the oil pickup tube.

With the original O-ring removed and the external nut removed, the internal adapter piece can then be dropped into the engine oil pan where it will reside forever now. Since the engine oil was drained before the process started, it’ll have an unrestricted fall and you should be able to hear it hit the bottom of the pan.

The most common style of repair you’ll find here is the old ‘slather on a bunch of silicone and hope it seals’ method. One of which we can assure you is destined for failure. Tired of dealing with constant repairs at their own repair shop, the team at Strictly Diesel in Phoenix, AZ developed an all-new billet dipstick adapter that can solve that oil leak once and for all. On the market now for more than a decade, Strictly has sold thousands of these adapters as it’s truly one of the only sure fire ways to eliminate the leaking dipstick tube on a 7.3L Power Stroke. Some guys try to fix their leak by just overtightening the factory adapter which can make things worse by distorting the cheesy factory adapter or even tweaking the side of the oil pan. Strictly’s design improves on Fords piece by using a dual external O-ring seal that is super simple to install while doing an oil change. The oil pan doesn’t have to come off of the engine, and swapping the adapter out can be done in less than thirty minutes once the oil is drained and the starter is removed.

The simple design and pre-threaded internal attachment can just be slipped through the original adapter hole and lined up for the second bolt to be inserted and torqued to the supplied specs. This design places even clamping force all the way around the pan and gives a great seal you’ll never have to worry about in the future.

Obviously, before installing the new adapter the outside of the oil pan was cleaned, and we removed any oil residue and silicone that had been used in a previous failed attempt to seal the factory fitting.

While on the subject of the starter, while fixing the oil leak it was determined our 27-year old truck was still running the original starter, and while it still worked, we had zero interest in bolting it back onto the engine and opted to upgrade here as well. The high output starter available from Powermaster offers a 200-amp output which is a substantial improvement over the factory unit and will ensure we have enough power to run any aftermarket components like an electric fuel system we plan to convert to later on. Their gear reduction starters for the 7.3L Power Stroke application and other diesel engines use a smaller motor that not only spins faster than a factory replacement would but is more efficient and draws less amperage while doing it. A gear reduction starter like this offers a much higher torque to spin over that big Power Stroke. It comes with a tough black wrinkle coat finish for good looks and better corrosion resistance and offers a one year warranty, with no core return required as they are built from brand new parts.

The Powermaster Gear Reduction starter we opted to install on this 7.3L offers many advantages over a stock style reman including being built from brand new pieces. So, there is no need return a core and the smaller, more efficient motor and gear reduction will spin harder and increases torque from the starter for easier cold starts.

As you can see here, it’s obvious we have some boost leaking at this turbo coupler that is going to need some attention. Which is a common failure point on any turbocharged diesel engine, but especially on those that run an internal crankcase ventilation system.

The final tech tip for this installment of the series will be related to the turbocharger system, actually the charge air system as whole, not specifically the turbocharger itself. This logic and insight can apply to any turbocharged diesel engine, and for the 7.3L platform the non-intercooled 1994-1997 trucks like used here, or the intercooled Super Duty Ford trucks too. Since these engines route the crankcase breather back into the intake tract, you’ll often see a lot of oily residues build up around the charge air boots on between the turbocharger discharge and the intake plenums found on the cylinder heads. On this non-intercooled truck, we have less points of failure, since there are no charge air tubes or air-to-air cooler to deal with. But the boots connecting our turbo outlet to the head inlet have a lot of that oil build up and without a doubt leading to boost leaks and poor engine efficiency.

To make sure we’re running in tip top condition we’ll be eliminating boost leaks with better quality boots for the plenums along with a set of billet machined plenum rings from Riffraff Diesel. The boots, clamps, and rings will allow us to seal better and clamp tighter for much better longevity and engine performance.

The factory tin plenums aren’t known for being very strong and while you wouldn’t think a worm gear clamp could be tightened enough to warp a metal plenum, it’s actually quite common to find these plenums crinkled and leaking. After years of neglect the leaking CCV pressure and boost pressure have dirtied everything up substantially. Since we’ll be upgrading to a better high torque t-clamp, we wanted to be sure the plenums would seal without issue, so the billet plenum insert is an easy remedy.

These trucks were never considered a powerhouse and that little turbocharger, while reliable doesn’t move a whole lot of air, so its vital we make sure as much of that air volume and boost gets to the heads as possible to ensure optimum performance potential. This truck only makes around 9-psi boost at wide open throttle, which is well below what it should produce. Using a simple boost leak tester, we’d purchased from KC Turbos for another project we were able to confirm our suspicions and found boost bleeding out in multiple places it shouldn’t be. Upon tear down and clean up of these charge air joints, we found a broken compressor outlet O-ring that was the biggest cause, but the leaking boots at the plenums weren’t helping matters either.

After removing the factory spider pipe to insert the new rings and install new boots, we also found this broken O-ring that was losing substantial boost between the turbo compressor outlet and the plenums. This was an easy fix with a new O-ring we also sourced from Riff Raff Diesel.

The billet machined sleeve can just be slid right down inside the plenum inlet and the machined groove around the upper edge can be bottomed out. Obviously, if your plenums are distorted at all, you’ll need to take care to get these inserted and get that plenum back into the original round shape. But once installed, we can torque those boots and clamp down much tighter for a leak free seal.

Riffraff Diesel of Eagle Point, OR specializes in just about everything Power Stroke and offers a bunch of replacement parts that will eventually find themselves on this truck, but we’ll start with their replacement charge air plenum Y boots, turbo inlet tube and plenum insert rings to eliminate our air leaks. The higher quality aramid/nomex reinforced boots from Riffraff are not only more durable than our oil soaked, cracked factory boots, but they’ll grip better for a more positive sealing surface. We also opted to upgrade to their T-bolt style clamps and toss our worm gear clamps in the trash, which allows us to put a little higher torque load and clamping force on those boots. The one other point to make here, is the factory tin style plenums won’t take much force to bend or tweak, so installing a set of Riffraff’s plenum insert rings will help ensure that inlet stays perfectly round and take that additional clamping force without creating a new failure point. While new boots aren’t always needed, for less than the $100 investment, it seemed logical to toss out the old boots while we have it apart, it also saved us a bunch of time from not having to clean the dirt, debris and oily build up from them. Cleaning up and resealing boost tubes and intercooler boots is a simple task just about anyone can accomplish and sealing up those leaks can mean better throttle response, improved fuel mileage, and of course better power potential since we’ll be using all the air our turbocharger is trying to feed us.

All back together and sealed up tight, we can count on all the airflow that little stock turbocharger provides finding it’s way right to the cylinder heads. This should help improve many aspects of the truck, from throttle response, turbo spool-up, mileage and of course power.

Speaking of power, before we went any farther with other upgrades, we were able to strap down on the Superflow Dyno at Edge Products for some baseline runs where this old 7.3 put down 185hp and 371tq. Not earth shattering numbers by any means, and definitely a number we’ll be able to approve upon with basic upgrades coming soon.

That rounds out the first few simple tech tips and easy fixes for getting an old Ford truck back into tip top shape but we’re far from done with this old gem. So, we hope you’ll continue to follow along and read through upcoming issues of Diesel World as we continue to help you breathe new life into your old ride, or just help enlighten you on some things to look out for under the hood of your truck, regardless of it’s make and engine platform.