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I finally found some time to take apart my spare power steering pump from the milano. My goal was to find aftermarket parts and sources to do a reasonable rebuild that the average owner could do on their own. I think I accomplished that and so far my pump is working great. The symptoms that I was trying to cure were leaking a little from the split line and turning the fluid to foam. Taking the pump apart is quite straight forward. I started with the pulley, it's on a keyed, tapered shaft so once the nut is off you should be able to pop off the pulled with your method of choice. I just supported the pulley in a vice and gave the shaft a good rap with a hammer and off it came. The key has to come out to and mine was a bit more stubborn. Woodruff keys should rotate out if tapped on one end with a hammer, no luck for me. I broke down a used some vise grips, just butted the nose up against the shaft over the key. Did them up real tight and tried wiggling front to back, this worked quite well. Now that the pulley and key are out of the way time to undo the two internal wrenching bolts at the back (allen heads or hex keys to most). These are on tight and may require a long ratchet or something, I used a careful hand on an impact gun. Once the bolts are out of the way open up the two halves over a rag or something, not only will a bunch of ATF come out but there is also a thrust washer that will likely drop too. Now you get to see the guts of your power steering pump, just like a little radial engine with pistons and a crank. There will be six small orings sealing around the high pressure passages and one larger oring around the pilot bore. We are going to change both of these as it would make sense to solve part of our problem of leaking around the split line. The bigger oring seals against suction so maybe part of our problem, I don't think so as it is surrounded by fluid and not air so may not be contributing to our foaming problem, I was on a roll anyway. At this point you should be able to slide the shaft out toward the back, there is a bronze bushing that goes with it, I always kept mine on the shaft wrapped in paper towel. I didn't want to drop it or something causing it to go out of round. Once the shaft is out it is a simple matter of removing the front seal. Once the seal was out I was curious to see how flat the mating surface was. I checked this by laping, all you need is a truly flat surface and some wet and dry sandpaper. Not many of us can afford a true surface plate with a granite one running into the thousands, an acceptable alternative is a section of plate glass. 3/16" or thicker is good enough and my chuck at work is a scrap that I got from the local glass shop that is close to a foot by a foot with finished edges. Just wrap a full sheet of what ever you have, I used 320 but coarser would be ok just be sure to finish it off with something 320 or finer. Give the paper a little spray of WD to keep the paper from plugging up and start laping. After a few figure eights you should have a fairly good idea on how flat your front housing is. Mine took 20-30 minutes of figure eights before the surface was uniform. Put the new seal in, I used an arbour press at work but a socket in a vise would work too, just make sure it is installed nice and square with no deformities. Next, clean everything up, I mainly used spray cleaners (non-chlorinated brake clean and electrical contact cleaner) and tried to not get very much in around the pistons so as not to wash away too much lubrication for the first start. Before you install the shaft back in the front housing fill the groove between the double lip seal and the edges on the taper of the shaft with wheel bearing grease or something so as not to cut the seal on install or have it burn out on the first start. I put a little anti-seize on the threads of my two long bolts, got my six small orings in place and the one large one over the raised boss. Make sure the thrust washer goes back in and assemble the two halves. I torqued the two bolts to 20 ft/lbs which was just a guess but seems to be working. Put the key back on the shaft then the pulley. To install back on your car you will need two 12mm and two 16mm copper washers for the two banjo bolts. 1/2" and 5/8" may work as well. Regarding the replacement parts the front seal is a CR 6412 which I got at a local bearing retailer. The six small orings are a 9682001003 from turbomeca and the one larger oring is a M83248/1-028 (or cross references to Parker 2-028 n0674-70, or mcmaster-carr 9452K115, from another member) which you should be able to get quite easily at a local aircraft parts house like Aviall. Or failing that try a local operator that does their own maintenance. Total cost for the parts was 2.20 for the seal and 1.00 to 1.50 for each oring. That's Canadian so half that for you yanks. If you are going to all this trouble anyway you should know that Alfa upgraded their power steering fluid reservoir from a brown one to a white one which has a changeable filter in it. At the time Alfa recommended changing the filter any time a component in this system failed. Refer to Alfa service bulletin 23-88-01 for this info. Having gone through all that, I would be tempted next time to just change the front seal to cure the foaming and call it done. Carson Damm The actual rebuild kits are available to Europeans as I was able to get one from a fellow on the 75 discussion forum. This was after the fact but they are out there and may be easier to find than the aircraft o-rings I listed. The pump part number for all 75's and Milano's should be a ZF 8601 955 117. |