Power Steering Hoses
INCOMPLETE -- TO BE FINISHED
HOWTO Replace Your Power Steering Hoses
or, how I spent my Memorial Day weekend
Alex Winbow, June 2006
Replacing the power steering hoses is a long, tedious, messy, unpleasant job. Customary advice is that when one hose leaks, all should be replaced. Three years ago I replaced one line, and now I've changed them all, and in neither case was it particularly well-documented. I hope this helps the next unlucky S.O.B. Much appreciation for a few posts on the SHOForum and the wonderful folks at TechSHO answering questions.
Parts and Tools
This is written based on a 1995 MTX, i.e. VAPS; the ATX should be easier, since the engine sits a little farther forward. The 89-92 MTXs may use different part numbers. The Powercraft brand is special-order at Autozone and PartsAmerica. The SHO has four power steering hoses:
- Reservoir->pump: this is a large (3/4"?) molded hose, no replacement seems available, re-use the original since it sees little pressure. No idea what to do if you cut it.
- Pump->rack: the pressure hose, Powercraft #71830. Metal fittings at both ends of a reinforced rubber line.
- Rack->cooler: Powercraft #91774. Metal fitting at one end.
- Cooler->reservoir: use bulk power steering hose, approximately 6-7ft. Where the catalogs say 78 inches appears correct.
Power steering hose is rated for oil and heat, normally only available 3/8" (ID), see spec SAE J189. In the words of the inestimable Sergio, "Whatever you do, don't use heater hose cause the oil will turn it to goo in a matter of months."
The three metal fittings seal with a Teflon o-ring; new seals will be included with the hoses, but the seal needs to be replaced each time the fitting is removed and reinstalled, and are easily damaged by over-torquing. Despite precautions, one of my hose ends did not install correctly the first time, and I had to go looking. For PartsAmerica and Autozone they are special order, my NAPA had them in stock. Teflon power steering o-ring, 16mm, part #7-2586, a bag of 25 and sold individually for $0.29. Buy spares. I presume these are the same o-rings at each of the three fittings.
You will want an 18mm open wrench for the fittings; many wrench sets only include even sizes. I also needed an 11/16" == 17.46mm, and it may be possible to get away with this instead of the 18mm. A crow's foot wrench would be helpful so that you can get a torque wrench on the fittings instead of guessing.
Spare hose clamps, in multiple sizes, to replace corroded or damaged factory clamps.
Also, lots and lots of sheet cardboard, paper towels, and disposable gloves. Power steering fluid will be *raining* from *everywhere*.
Try to drain as much fluid from the system as you can. Begin by sucking the fluid out of the reservoir with a turkey baster, destined never to baste (food) again. The lines at the cooler are the lowest point and easy to get to, but tend to spew onto the subframe, then down your jack stands, etc. There are alternative methods of draining I haven't explored, like removing the return line at the reservoir, diverting to a bucket, and then turning the engine over to try to pump fluid out of the system. See the SHOForum. Exercise creativity with funnels, assorted drain pans or cut-up plastic bottles, which you will want need to cram into tight working areas while on your back. After draining, have a drink -- there's lots more fluid mess to be made yet.
The p/s hoses run three-quarters around the engine bay. For anything other than the rack->cooler hose, a lot of the action takes place in the Darkest Corner, the subterranean area at the right-front engine corner (passenger side firewall). Replacing the pump means going in from the wheel well, see Scott Patterson's (sdpatt) post on the SHOForum. I went in from the top, so while I removed the wheel for visibility, I did not remove the roll dampener, wheel well dust cover, tie rod, etc.
Begin by removing the intake manifold, as usual. Unbolt the two bolts securing the fuel lines. Unplug the CID (camshaft) sensor. Move wiring and vacuum lines out of the way. Now you can see the pump, suction line, and the return line rising from the deep. I needed a lot better access than that, for swinging the wrench and for starting the replacement pressure hose. That means getting the engine wiring and that metal tray out of the way. There are four wiring harnesses that unplug in the tray. The plastic connectors ride on metal clips riveted to the tray; I found I could bend the clips back and slide the connectors off. Unbolt the harness to the PCM (main computer) on the firewall. All this seems like a waste of time, but huge empty space opened up is worth it's weight in gold ... or something, later on.
As you disassemble this corner, note carefully the positions of the many components. The metal wiring tray bolts to the funny upper bolt of the intake manifold support bracket (between the integral nut and the second outer nut), along with the grounding strap. The lower bolt holds a support-bracket for the return line. Observe it's orientation, and how the pressure and return hoses route down there (I didn't, and had to play guess-the-jigsaw-puzzle later.) The AC pressure line is right there, so extremes of hot and cold, vibration, the power steering pulley, and engine movement mean danger abounds for your fragile hoses.
For accessing the rack->cooler line alone, removing the intake makes it easier but you can probably get away without it. Remove the throttle body, upper radiator hose and thermostat pipe, and the coilpack, plus wiring. Remove the coilpack support bracket, held on by three identical bolts, one of which you can't see. You can now get to where the pair of cooler lines run through a hose bracket at the top of the transmission.
Under the engine, remove the heat shield protecting the steering lines from the exhaust manifold. Mine was soaked with fluid, and there's no obvious replacement. Observe the hose routing down from above in both directions.
Removing old hoses
The reservoir->pump line, although you probably won't replace it, needs to be removed for access. I find vise grips the best tool for the factory hose clamps. Annoying as they are, you may want to reuse the factory clamps -- they seem more rugged than the usual screw type.
The OEM pressure hose is an 18mm fitting. Mine was stuck very tight, and my shiny new 18mm wrench started to round off the head. So did channel-locks and visegrips. This is scary. If the head is too damaged, one option may be to work a dremel down there and cut through the rubber hose and the metal collar, then slip a box wrench over the line. I noticed that the fitting on my replacement pressure hose was 18mm, but also (just barely) fit an 11/16" (=17.46mm) wrench. The OEM fitting did not fit the imperial wrench, but could be pounded on, gently, with a mallet and block of wood. That was very secure, and with a lot of force the fitting, mercifully, came out. No, it's not a left-handed thread ;)
The preceding applies to the two fittings on the rack, for the pressure and cooler lines, but for me those were not nearly as tight. There's not much arc to swing the wrench, but visibility is much better.
The hoses at the the cooler may be very tough to pull off the metal nipple. Cut the hoses longitudinally as necessary.
Installing new hoses
As you route the replacement hoses around the engine bay, the three metal fittings ought to be protected. I cut fingers off disposable gloves and slipped them over the fitting, secured with a twist-tie. You may want to wrap the rack end of the pressure hose with paper towels and tape for protective padding. See next paragraph.
Getting the new pressure hose fitting started at the pump is a complete PITA. Although the fittings swivel, the end is fairly tight and not that easy to turn by hand. You have to get and keep the fitting properly square onto the pump outlet, then rotate the fitting enough to start the threads, all one-handed. The weight of the hose keeps tension on the curved metal part of the hose behind the fitting, trying to torque the fitting away from whatever angle you are holding it at. You can play all kinds of games positioning the far end of the hose so as to make your life least difficult at the pump. This is also why you want the thick PCM wiring harness out of the way, and far end of the hose with its own precious fitting protected for all the times the hose flops around like a tortured snake, before dropping it entirely. This part of the job might be made much easier by having an assistant hold the hose and take the weight/stress of the hose by grabbing it from the wheel well, while you line up the fitting on the pump and start the threads.
Patience and care are vital, since you dare not cross-thread the blasted thing, or nick the o-ring.
The o-rings can be replaced if damaged. The Teflon seal is too small to slip properly over the fitting threads, but can be stretched wider. The Ford book specifies a particular tool, or slip the seal over the end of a cone. I didn't have any children's toy blocks around, so I stretched the seal between two smooth screwdrivers shafts (like a belt across pulleys). Very gently stretch the o-ring, then rotate the belt a little and stretch again, so as to spread the stress over the entire ring. This is why a conical tool is better if you have one. After working the o-ring into the fitting mine took several hours to lose the excess stretch.
The same applies for the two fittings on the rack, although they are much easier. They are also easier to access and re-do if, after you refill the system, you find it leaking. It is important not to over-torque these fittings. The instructions included with my Powercraft hoses specified 10-20 ft-lbs, and the Ford book says 10-15 ft.-lbs. for "Pump Pressure Line Fitting", and 15-25 ft.-lbs. for the "Gear Hose Fittings". If you have a crow's foot extension you may be able to use a torque wrench, plus appropriate trigonometry to calculate the measured torque from the true torque. I did not, so used the muscle-memory method: put your torque wrench on a convenient bolt (I use the stut towers), pull to the proper torque, and try to memorize the feel, or if using one finger, the level of stress or pain. Your box wrench may be shorter than the torque wrench, so increase the force needed proportionally for the same torque (e.g., if the box wrench is 12" long, and the torque wrench is 18", then a true 15 ft. lbs. with the box wrench will require the same force from your hand as generates 18/12 * 15 = 23 ft.-lbs. on the torque wrench).
Here are confused notes from my draft concerning the Teflon o-rings. As above, I actually used NAPA #7-2586. Not sure if these could also be used: rack seals: 388897-S (.455" ID) 388898-S (.515" ID) Also Motormite makes them, part number 82540
Alex 15:51, 18 June 2007 (CDT)