From hill-to-dale or mud-to-boulder, our lifted Jeeps see more stress than the factory ever intended. We twist driveshafts, bend differential covers, mangle sheetmetal, and inflict damage on things that we often don’t even see. One of those things we don’t see or think about until it’s too late is the power steering system. It isn’t until we hear that whine coming from under the hood or can’t steer in some rock garden that we worry about it.
Once it goes bad, many Jeepers overcompensate with upgrades. The truth is that if you are running 35-inch tires you don’t need a hydraulic assist ram, and for most guys running 37-inch tires a ram isn’t needed. Yet we keep running across Jeeps with dual-ended rams and the thing doesn’t have one rock scar on it.
Once you hear that moaning from under the hood, you need to inspect your fluid for metal particles. There is no filter in the system, and driving the Jeep with either the box or the pump in bad shape will kill the other component in no time. On older, V-belt-equipped Jeeps you can just pull the power steering belt. That’s a little harder on a serpentine-equipped Jeep, so replacing the pump and box at the same time is often a good idea.
Our plastic pulley was already...
Our plastic pulley was already cracked, so we picked up an aluminum replacement pulley from Gen Right Off Road. It is machined to help cool the pump by promoting air flow over the reservoir. Speaking of reservoirs, PSC offers its pumps with brand-new reservoirs already attached. Often the 20-year-old plastic reservoirs are either leaking or break upon removal and thanks to the spring-clip hold-downs it is difficult to keep even a successfully swapped reservoir from leaking.
There are many variables when it comes to selecting a power steering system for a modified Jeep. When the time came to replace the power steering on our ’91 Comanche we contacted the experts at PSC Motorsports for a high-quality replacement pump and box. The company offers many replacement options, so when you call be up-front about what you are putting your Jeep through. The company might suggest a stock-sized box for one guy but a bigger box for another guy, even if they have identical Jeeps. The company suggests its regular replacement box for up to 35-inch tires with light use, the bigger-bore replacement box for 35-inch-and-larger tires with heavy use, and hydraulic ram-assist for 37-inch tires or bigger with heavy use.
So, we ordered the large-piston steering box and direct-replacement pump for our MJ. As we were working our way to one-finger, leak-free steering, we shot some pictures of tips and tricks we’ve learned over the years so that you can do your next power steering system swap like a pro.
Bleed It Out
Properly bleeding the system is very important. The air pockets that are in the system when you first fire up the vehicle can kill the pump. It is a time consuming process, but worth it. Step 2 sometimes only has to be done 10 times, but we’ve had to do it 40 or more times too. Patience is key.
Step 1 - Put the front end up on jack stands with the tires off the ground.
Step 2 - With the engine off, spin the steering wheel from lock-to-lock (the full 3¼ turns) about three times. Five times is okay too, but ten times back and forth is a little excessive.
Step 3 - Using a flashlight, look into the reservoir for air bubbles. If there are no air bubbles increase the number of lock-to-lock turns.
Step 4 - Once the air bubbles disperse, repeat. At the beginning of the process it usually takes around 10 minutes for the bubbles to go away.
Step 5 - When no more bubbles surface but with the front tires still off the ground, fire the Jeep up and look for bubbles.
Step 6 - If there are no bubbles, and with the Jeep running, turn lock-to-lock three times.
Step 7a - If there are bubbles, shut the Jeep off and wait for them to disperse. Go back to Step 2.
Step 7b - If there are no bubbles, put the Jeep on the ground and spin the wheel lock-to-lock a few times while listening for any noises and look for bubbles. If you still have a lot of bubbles or hear noises, start again, you probably didn’t repeat the wait-for-bubbles steps enough times. If there are only a few bubbles, it steers easily, and you hear no bad noises, enjoy your new steering system.
Before you start on the swap,...
Before you start on the swap, pick up a pitman arm puller and a power steering pulley puller. You can often rent or borrow them from your local parts store but they aren’t that expensive and will get more use than you might think. Also make sure the Jeep is parked with the tires and steering wheel pointing straight.
Many of the Unitbody Jeeps...
Many of the Unitbody Jeeps used three-bolt Saginaw-style steering boxes rather than the four-bolt mounting that most Saginaw boxes used. The three-bolt box was then fastened to the Unitbody with a thin aluminum mount. Toss in some big tires and some wheeling and broken boxes, mounts, and a bent Unitbody is the result. This heavy-duty mount from TnT Customs solves all those problems. We ordered the steering box from PSC in the normal four-bolt mounting pattern. However, because we went with the larger piston box, we had to remove the middle through-frame bolt because the head interfered with the body of the box.
All good steering boxes come...
All good steering boxes come with new O-rings for the fittings if they are required. Pull the old O-rings off the hard line and replace them. Even if your box doesn’t come with O-rings, pick some up. Inspect both the high-pressure and return hoses for any cracks or wear. If the high-pressure hose is damaged, you’ll have to replace it with a vehicle-specific replacement. The return hose is simple oil-resistant 3⁄8-inch line, secured at either end by a hose clamp.
In addition to the steering...
In addition to the steering stops on the axle, the steering box has its own internal stops. Once the steering box is bolted in, but before you hook up the linkage or fill the system with fluid, double-check that it is still centered. The box should arrive centered, but a simple turn-and-a-half either way at this point can save a lot of work later. The box actually has 3¼ turns lock-to-lock but that extra little bit can be adjusted out with the drag link.
Reuse the old pitman arm nut...
Reuse the old pitman arm nut to push the pitman arm onto the box. We use the 15⁄16-inch socket with the impact gun one setting down from highest. Once the pitman arm is on, grab the new lock washer and nut and torque to 170-210 ft/lbs. Even with the lock washer we still use thread locker on the nut. Have a friend hold the pitman arm steady to avoid strain on the steering wheel lock in the steering column.
With the kind of abuse we...
With the kind of abuse we dish out on our steering systems a lot of heat is generated. A power steering cooler just makes for more complexity, so we opt for fluid that can get hotter before breaking down. Royal Purple Max EZ steering fluid can handle more heat than regular power steering fluid. Our system took just under three 12-ounce bottles to fill.