Repairing power steering

I'd like to take the opportunity to dispel a couple myths and fables about repairing power steering control valves and to show how easy control valve repairs really are.

The parts cost $10-$15 for a reseal kit at local parts store or a more complete kit including dust cover, ball stud and return spring for about $40 are both available from most Cougar/Mustang Vendors or from Scott Drake Products. You can get a new slider and ball stud in addition to the seals, but for this repair the inexpensive kit is all that is needed in most cases.

Ten dollars or $40, you decide. Both will fix the problem, as the $40 kit has all of the parts in the $10 kit, plus a new ball stud, cups, spring and dust cover. Most of the time the $10 kit is all that is required to fix a control valve problem. area

First, understand that the power steering control valve is basically a hydraulic gate valve directing fluid pressure when turning the steering wheel. Turning the wheel allows fluid to pass at 1500 psi through the gate and to the appropriate side of the power ram depending on which way you are turning.
The control valve is not often the culprit of a power steering problem. If it is not leaking, it is probably okay. Loose steering is not a symptom of control valve trouble; however, a leak or hard steering may be. Very often loose steering is due to an idler arm or ball joint being worn, which brings me to the control valve's other half; the ball stud and slider. The ball stud within the slider housing is attached to the pitman arm and pushes or pulls on the spool actuating rod allowing fluid to fill or empty the cavities in the power steering ram.

Although the control valve, shown here on the right of a power ram cylinder, is easier to work on when removed from the car, the technique shown here shows how to rebuild the control valve without having to remove the entire control valve from the car. ent area

The ball stud and slider must slide freely and not bind. If the control valve assembly is removed with a pickle fork it will damage the slider and housing, which is why a pickle fork shouldn't be used except when removing parts being replaced. The great thing about this repair is there isn't any reason at all to remove the ball stud and slider to reseal a control valve. In fact we only need basic hand tools for this job, and it only takes a couple of hours to accomplish.

  Slot screwdriver


  5/8" Wrench

  Jack stand


  Magic marker

  1/2" Brake line wrench

  Masking tape

  Wire brush

  Cleaning fluid

  Catch pan


Doing the job:

Begin by getting Cat off one paw, front left, and turn wheels fully to the right to allow easier access to our Cat's leaky control valve seals. Up on three paws with the wheel turned full to right allows easy access to the control valve once tire is removed.

Degrease the control valve in place before any disassembly begins and keep it clean during the entire process. A little solvent or spray degreaser and a small brush will get off dirt/grime, and brake cleaner will flush any left over grease into a collection bucket placed under the control valve.
Keep the collection bucket handy, because we will also need it for the fluid which is about to spill out as the hoses are removed. Now that control valve is exposed and clean, start by marking the PS hoses with the masking tape. Mark the hoses to indicate which hole they go back into, and then remove them. It is critical that the two hoses feeding the power ram are marked absolutely correctly to prevent any mix-ups when reinstalling the hoses.

Using the line wrench, loosen the three 1/2" hoses and the one 5/8” hose, which is the return hose. Let the fluid spill out into bucket while removing the two screws holding the control valve end cap on with a regular screwdriver. When the cap is off it exposes a 1/2" nut, which has to come off next.

Take the 1/2" nut off, as well as the spring, washers, and adapter plate. Place these parts on the bench in the order they come off. Clean the parts one at a time and place them back in their proper location in the line.

Unthread the hoses the rest of the way, noting how the hoses are aligned to each other. Now undo the two 1/2" bolts holding the front half of the control valve to the slider housing, allowing removal of the control valve housing, which is the item that needs new seals. This will expose the actuating rod. Notice how it all fits together.

Clean up any missed dirt and plug the holes for the hoses if need be. If you keep the hose holes facing downward there should be no problem keeping them clean. Use a pair of pliers to pull the two caps out. Any grit can foul the system, but it is possible to do one seal at a time and not completely remove all the little springs and other parts in the gallery if you work carefully and keep things clean.

Carefully lubricate the new seals with power steering fluid or automatic transmission fluid, whichever you use in the power steering reservoir. Replace the O-rings on the lower smaller plugs first, then push them back into the control valve housing. Now the spool end seals can be popped out one at a time. These are the ones that will leak and are a bit tricky to install, so be careful to not tear the lips as you tuck the new seal into the housing. Begin with the spool remaining inside the housing and then install the other seal.

This is the valve spool, where most leaks occur. Take your time when installing the seals here because damaging a seal could result in a worse leak than what you started with.

Place the front half of the control valve with new gasket on the actuator rod and install the two 1/2" bolts. Now, place and position the return spring and all washers/spacers in the exact order back on rod. Tighten the 1/2" nut all the way until snug, then back it off no more than 1/4 turn. Yes, back it off 1/4 turn and place the cover back on, being careful with the square cut O-ring that protects the return spring under the end cap from moisture and dirt. Install the hoses next, being very careful to put them back in their original positions.

The grease zerk is on the underside of the control valve. If yours has a plug in it, it is a good idea to remove and replace the plug with a grease nipple to give the slider some lubrication and extend its life expectancy. Now is also a good time to squeeze some grease into the other grease fittings.

Pour in enough power steering fluid to replace most, but not all that was lost when the hoses were removed. With all hoses and gaskets and seals in place, start the car.

Do NOT put your arm through the steering wheel to start the car!
Stay clear of the steering wheel completely.

Start the engine and, if the steering wheel just sits there like normal, great! You've done it. Turn the wheels back and forth completely a couple of times in both directions to purge air from the system. Remove the car from the stand, and recheck the level. Now top off the system with fluid.

If by chance the steering wheel has taken on a possessed demeanor, serious injury can result from the steering wheel itself, so very quickly shut off the engine. If your steering wheel is bouncing around all on its own you have the ram hoses backwards. Remove the two hoses from the ram at the control valve only and reverse them to correct the problem.

Here the control valve has been reassembled back in place. We're almost ready for a test drive.

All control valves are the same for millions of cars produced over 25 years. Control valves to experiment on or to get parts from are abundant and a spare control valve and $10 worth of parts is a good place to start the learning process. The secret really is to do one seal at a time and to mark and lay out parts exactly so they go back in exactly.

If the ball stud and slider are damaged due to improper removal or lack of lubrication, the process is a little more involved. If the entire control valve has to be removed, use a ball joint splitter--not a pickle fork--to separate the ball stud from the Pitman arm. You may be able to push a long bar down through the engine compartment to the top of the stud with the pitman arm braced from below. First, remove the cotter pin and loosen the ball stud nut enough so that the top of nut is flush with top of ball stud threads before hitting the long bar with a hammer to free the ball stud from pitman arm.

Basically an overgrown tie rod end puller, the Pitman arm puller is available at most parts stores as part of their tool rental program. This is the proper tool to remove the control valve from the pitman arm, even if the plan is to replace the ball joint and slider.

After removing the retaining clamp and removing the ball stud out of the pitman arm, there is also a roll pin that has to be pulled out of the center link. Use a pair of pliers to pull the pin out. Spray a quick dab of paint on the center link, then rotate the control valve off of the center link. Make sure to turn the control valve counter-clockwise to remove the valve. Turning it in the wrong direction will remove the paint, which means taking the car to the alignment shop.

The valve is disassembled the same as noted above, but to remove the ball stud, wash the end free of grease to expose a set of holes drilled through the stop screw. Push the pin out of the stop screw, then unscrew the part out of the housing. The ball joint can then be removed from the housing and the slider will also come out. As with the other parts, keep them in the order they came out. It is critical that the correct amount of tension is placed back on ball stud and cups when returning the actuating rod to the slider. Thread the rod back as far as it will go and still allow the locating pin to be placed back inside. If it is too loose, the ball stud may fall through the slider and render your cat unsteerable.

If the procedure seems confusing, don't worry. This handy diagram comes in every seal kit and in every ball stud kit. If you lose track of the parts sequence, just refer to this diagram and you will be fine.

Time to take the car for a test drive. Check the valve when you get back for leaks, but the rebuild we just completed should solve the any leaky control valve issues. Catzyalater