Tips for rebuilding your AYC pump

Discussion in 'Maikoworks' started by eyeballprawn, Jul 14, 2016.

  1. eyeballprawn

    eyeballprawn Maikoworks Trader

    Joined:
    Feb 7, 2009
    Messages:
    4,318
    Likes Received:
    487
    Location:
    Vic
    First Name:
    Dylan
    Drive:
    2003 Caldina ST246
    2000 Legnum VR-4 RIP
    1994 Bluebird SSS
    ☠ Hyundai of Death ☠
    I seem to keep answering the same questions by private message, so I'm putting this info out there for reference when rebuilding your pump using my AYC pump overhaul kits.

    Smear some vaseline on the o-rings that go either side of the pump plate them to help hold them there. Actually, the pump gears should also be very generously covered with vaseline, pack heaps in. Vaseline is recommended by Mitsubishi for their transmissions as being compatible with their SP3 fluid, it will safely dissolve into it.

    The middle area should not be touched, it's important that it retains the factory machined finish. Unless of course yours was corroded there and you had no choice. I also would not use a wire brush on the o-ring grooves. Is there is dirt inside try to pick it out with something that won't scratch the metal or use a fine sandpaper like 1200 grit.

    middle.jpg

    I include some thick protective stickers you can use to protect the inner area while you work on cleaning up the area around it.

    protect.JPG

    Be sure to fit the pump plate the correct way out and with the VR4 pumps the text should be the right way up when the pump top is face up as it would sit in the car.

    alignment1.jpg

    The drain-back hole on the back half of the pump body needs to be oriented down towards the bottom of the pump, so that the oil that got behind the gears can drain back out. You will also notice that the semi-circular grooves behind the pump gears need to match orientation with the ones on the pump plate. I usually don't put the new motor shaft oil seal on until I've put the pump halves together just so I can do a final confirmation it's facing the right way.

    drainback.jpg

    Ensure the pump gears are fitted with the dot marking facing outwards towards the pump plate. Also check that the spindle pin is seated correct.

    gears.JPG

    Seal around the outer join of the pump body sections with grease, I don't recommend to use silicone sealant in case you need to pull it apart again and try again.

    alignment3.jpg

    With the stainless plates, it's important to not over-tighten the pump body bolts during re-assembly. Otherwise it will press the pump gears too hard against the plate and make them difficult to turn. There is a potential to seize the pump if oil isn't coming through and it's run for more than a few seconds at a time like that.

    bolts.jpg

    You can check by turning the spindle with a screwdriver, it should move freely. If it feels like it's binding at all, you need to loosen the bolts off. The Mitsubishi plates are aluminium which being softer avoids some of these things, but then as we know it has other problems.

    spindle1.jpg

    spindle2.jpg

    Check that the motor bearing has been correctly fitted to the motor shaft. From the bearing outer surface to the end of the motor shaft should be 12mm exactly.

    motor-bearing-depth1.JPG


    If the pump doesn't seem to be sucking in fluid and pressuring and you are certain you have assembled everything correctly, it's most likely you haven't purged the pump properly and there is air inside it. Hold the pump on end with the pipes facing up and using a funnel pour fluid down both pipes. Run the pump a second and do it again, then repeat a few more times. Anytime you suck air in you need to re-purge. After there is some fluid in the pump, hook up the AYC reservoir using both hoses, add plenty of fluid to that and be sure to keep it topped up while testing and held up so no air gets into the pump.

    If you find that it's not holding pressure you may have a dead accumulator bulb. Gently insert a thin long screwdriver or heavy gauge wire into the accumulator bulb neck (I use a piece of coat hanger wire), if it goes further than where the neck meets the bulb then the diaphragm is ruptured and you need to replace it. You may be able to get a suitable one from a local hydraulics shop, or find a good used one. They can't usually be shipped by air though due to being pressurised. These photos show a bulb with a good diaphragm.

    accumulator2.jpg

    accumulator1.jpg

    The diagram below shows an ABS accumulator bulb, but it's the same thing and gives you an idea of what's inside. Because the AYC bulbs are purpose build, there is no serviceable gas charge port.

    accinside1.jpg

    Usually if there is air inside the pump they won't suck fluid through when the pump is in the normal horizontal position. So you'll need to angle the pipes up until the air is out.

    angle.JPG

    The other thing to check is that you have the polarity on the pump motor correct. Once I was tired and couldn't figure out why it wasn't pumping, then realised I had the wires the wrong way and was running the pump backwards.

    If you previously did a test, it will take at least 30 mins to an hour for the pressure to subside to where the switch will reset unless you fire the solenoids. Also you need to block the outlet ports with blanking plugs to properly test as the solenoids are a pretty crappy seal and weep a lot of fluid through. In general, I go through a couple of litres of fluid when I test the pumps after purging all the air out and firing the solenoids a few times.

    If anyone has questions please ask here so others can benefit from the information.
     
    Last edited: Jul 14, 2016
    Smurph, Relmz, fubar and 2 others like this.
  2. Grid

    Grid Leaving Skid Marks

    Joined:
    Apr 12, 2015
    Messages:
    87
    Likes Received:
    35
    Location:
    Poland
    First Name:
    Tomasz
    Drive:
    Legnum 6A13TT, Galant 6A13
    I can just add that if you get this wrong, you apply voltage and pump just turns and constant rpms and not suck fluid in, try to reverse the polarity. If the pump starts working normally then you know you got it on backwards. Happened to me.

    Also - a question, do we know the standard parameters for the accumulator? I am trying to order a replacement, the oil thread is M16x1.5, pressure I am guessing its a diaphragm type, 20bar of N2. Is the capacity known? Looks like 0.3 or 0.5l
     
  3. Grid

    Grid Leaving Skid Marks

    Joined:
    Apr 12, 2015
    Messages:
    87
    Likes Received:
    35
    Location:
    Poland
    First Name:
    Tomasz
    Drive:
    Legnum 6A13TT, Galant 6A13
    To answer my own question - it's a 0.16l capacity. I've fitted a 0.3l one to my pump, although it required cutting a hole in the pump support tray since the new bulb was longer. This may hold true even for the properly sized one since most accumulators you can buy feature a second service thread for checking / replenishing the nitrogen on the other side of the diaphragm and since you virtually can't buy them with the proper thread so a converter is required (1/2in to M16 in my case).

    Also according to accumulator system design guidelines I found from one of the manufacturers - you are supposed to have the diaphragm pressurized to about 0.9 - 0.95 of the typical operating pressure (not maximum). Pressure switch closes at 16bar - this seems to be the desired operating pressure. Hence I've ordered my accumulator pressurized to 15bar.
     
    eyeballprawn likes this.
  4. Grid

    Grid Leaving Skid Marks

    Joined:
    Apr 12, 2015
    Messages:
    87
    Likes Received:
    35
    Location:
    Poland
    First Name:
    Tomasz
    Drive:
    Legnum 6A13TT, Galant 6A13
    DSC_0843.JPG
    This is what the pump looks like with the bigger bulb. Moments before I coated it all with underseal lol
     
    eyeballprawn likes this.
  5. Grid

    Grid Leaving Skid Marks

    Joined:
    Apr 12, 2015
    Messages:
    87
    Likes Received:
    35
    Location:
    Poland
    First Name:
    Tomasz
    Drive:
    Legnum 6A13TT, Galant 6A13
    Oh yeah and I keep forgetting to add this tip here.

    When opening a corroded pump for the first time. To pry the corroded plate off you don't need to cut the sides of the housing (which looks ugly afterwards). Just use a M6 tap and M6 bolt, tap one of the steel pin holes, screw the bolt in just a tiny bit, so that it only holds onto the plate and.. use a carpenters hammer to pull it out like a nail! It will come off with the plate. Use a metal flatbar resting on the pump casing for leverage.

    Of course this will only work if the plate is not corroded to smithereens. But if it is, you won't have a problem removing it anyway as it will just peel away.
     
    TME_Steve and eyeballprawn like this.

Share This Page