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Project: Fixing a Leaky Power Steering Pump

Write up and pictures by: Harley C
Car model: 1991 Honda Prelude SR
Engine model: Honda B21A1 

Nothing ruins a Saturday like finding out that your power-steering pump has sprayed power-steering fluid all over your engine bay. I guess my car decided it was high time I did a little work on her; after all, it had been a full day since I had last been turning wrenches. Cars can be so needy.

At first, I was very puzzled by what had happened. There was a light-colored fluid all over my engine, the underside of the hood and throughout the engine bay. Since I almost always run synthetic oil in my engine (which is very light in color), my first guess was that one of my engine oil seals had "given up the ghost" and subsequently engine oil was leaking onto my belts. I figured that the belts were responsible for the fluid being nicely distributed throughout the entire engine bay.

Upon further inspection, I determined that the fluid in question was not engine oil, but rather power-steering fluid. I've always found synthetic engine oils to have a very distinctive aroma and feel about them; the fluid was certainly not engine oil. Power-steering fluid on the other hand doesn't have a very distinctive odor, but it'll numb your finger tips if you touch it. As soon as I noticed that I couldn't feel my fingers anymore I was quickly able to correctly identify the mystery fluid.

I was, however, still very puzzled. I was sure what the fluid was power-steering fluid, but I wasn't positive on how it had come to be distributed all over my engine bay in such an abominous fashion. I could find very little trace of the fluid on my accessory belts, leading me to temporarily believe that one of my power-steering high pressure lines had a hole in it. I checked all of them, no leaks.

It was at this point that I recalled an article I had read a long time ago about what happens to Honda power steering pumps when their shaft seals go bad. On 2nd generation Prelude PS pumps, it is quite common for the PS shaft seals to fail. When this happens, it most often results in the pump sucking in extra air and bubbling air into the lines and reservoir, ultimately resulting in the reservoir overflowing and spilling fluid all over itself. Was my problem similar?

I took a closer look at my PS pulley and discovered that it was coated with PS fluid, as was the shaft driving it. The PS shaft seal had to be the culprit of my troubles. So, in true Harley fashion, I took it apart to figure out what the malfunction was all about. The oil seal needed to be replaced.

The first step to getting the oil seal out of the PS pump is to loosen the tension of the PS belt. On a 3rd generation Prelude, this is not the easiest thing to do. Generally speaking, Honda cars are very easy to work on, but sometimes, things are just in awkward places. The PS belt tensioner bolt is an example of an 'awkward place'.

First of course, you have to loosen (not remove) the lock bolt at the top of the PS pump housing that connects it to the accessory bracket. Loosening the tensioner won't help a tiny bit if you don't loosen the lock bolt. Then, start loosening off the tensioner to get some slack in the PS belt. This is an arduous process, and it'll have you pulling your hair out faster than a puppy who uses your new leather couch as a chew toy.

To get at the tensioner bolt, I fashioned a unique setup on a 1/2 inch ratchet driver. I attached a extra long 1/2 inch extension, then a 1/2 universal joint, then a 1/2 inch to 3/8 reducer and then finally a 14mm socket. Believe it or not, this is actually the required setup to get at the tensioner bolt. I tried a variety of other approaches (one of which involved removing the under-car splash guard), but this one worked the best. Take a look at the picture and you'll understand how my ratchet was set up.

Getting the socket to reach the tensioner bolt is a bit of a hastle. My approach was to feed the long extension down in front of the alternator and then bend the universal joint so that the socket would go onto the tensioner bolt. It takes a couple tries, but once you get it, it's easy. If you look at one of the pictures you'll see in the background how I had fed the wrench down into the engine bay.

Once you loosen the tension in the belt, slip the belt off the pulley and lay it to the side. There's no need to take the belt right out of the engine bay it should just hang there out of the way. Next, take the pulley off the PS pump. The bolt for the pulley has left-hand threads, so you have to turn it CLOCKWISE to loosen it. To prevent the pulley from rotating as you remove the pulley just jam a screwdriver through one of the holes in the pulley and lodge it on the side of the PS pump housing. The pulley bolt shouldn't be too tight, but it will likely be a little bit seized.

With the pulley out of the way you will be ready to take the front piece of the housing off the PS pump. There are four bolts on the pulley end of the housing that you will need to remove. These bolts should not be too tight, and you won't need any special tools to get them off. Just remove the bolts then pop the loose piece of the housing off.

Once you have the housing apart you will see how the oil seal has been pressed into the piece of the housing you removed. This is the oil seal that needs to be replace. A new seal from Honda will cost you about $10. It's probably a good idea to go with an OEM seal; Honda parts are very good quality.

You should be able to press the old seal out with your hands and a screwdriver. They're not in super tight. Once you've got the old seal out, clean the area where the seal sits, then press in the new one. You'll be able to press the new seal in part way with your hands. To press it in the rest of the way, get a large socket that is approximately the same size as the seal, place the socket on top of the seal and gently tap it in with a hammer. (see diagram)

That's all there is to it, you're done. You just have to reassemble everything you've taken apart. The first thing you'll need to do is put the end of the housing back on the PS pump and tighten the four bolts (tighten to 9 ft-lbs). When you put the pulley back on, Honda suggests torquing the pulley bolt to 24 ft-lbs.

With the housing and pulley all back together, all that's left to do is put the belt back on and set the belt tension. Slip the belt onto the pulley, then use the belt tensioner to tighten up the slack in the belt. Honda suggests that the belt should deflect about 0.4 to 0.5 inches when the tension is properly set. Once you are satisfied with the tension in your belt, tighten the lock bolt, top up the PS fluid reservoir and go for a drive.