What causes a PAS rack to blow its seals.
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  1. #1
    1000+ Posts jo proffi's Avatar
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    Default What causes a PAS rack to blow its seals.

    I'm getting really good at removing and replacing fuego steering racks.
    2-3 years is about as long as one lasts before needing a rebuild.
    They never seem to get leaks either. Its always monumental blow outs (sorry motor bike riders) with little warning.
    Last night doing a trailer run with lots of slow speed manoeuvring it gave way and dumped enough fluid that the rest turned to pink froth. Fuego is now dead.

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    What helps promote early seal failure??
    Is there anything I might be doing to promote the early failure of the rack seal ??


    Jo
    Last edited by jo proffi; 16th May 2013 at 12:53 AM.

  2. #2
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    Is there any rhyme or reason to the failure? Does it happen after a long and hard winding drive or just randomly?

  3. #3
    1000+ Posts jo proffi's Avatar
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    Seems random.
    I've been fairly easy on the car recently, no national parks and those types of drives that really heat the steering up.

    Just the occasional slow speed reversing with the trailer is as hard as it gets.

    Jo

  4. #4
    Fellow Frogger! Roland's Avatar
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    Could be a partially blocked low pressure return pipe.

  5. #5
    1000+ Posts jo proffi's Avatar
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    Quote Originally Posted by Roland View Post
    Could be a partially blocked low pressure return pipe.
    Hmm. That might be an issue.
    It is longer than OE and might have taken a hit or something that restricts its passage of fluid.
    I'll re make that line in a larger diameter pipe just to be sure.

    Jo

  6. #6
    1000+ Posts 504-504-504's Avatar
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    Not sure if its of any relevance but I avoid full lock on power steering equiped cars.
    Maybe hit full lock then back off a bit.
    Don't like the sound of the pump as it builds up pressure trying to move the immovable.
    Can't be doing anything good.

    Paul.

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    Hi
    Are the seals you fit correct seals for this application. 'Normal' seals are not rated for high pressure or sliding rod sealing. Perhaps look into the type of seal you are being supplied ??
    cheers Jaahn

  8. #8
    1000+ Posts HONG KONG PUGGY's Avatar
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    Jo. If you need to rebuild again, try Lucas power steering stop leak and run it as the fluid for the system.
    It is a little thicker than normal and truly does work at fixing leaks.
    Used it many years ago on both an R20 and 505 and it stopped leaks in both. Apparently it rejuvenates the seals and as it is thicker I found it quietens the pump as well. It's in the Scenic power steering as I did a fluid change a few years ago and did a half fill of normal fluid and Lucas fluid.
    The fact it is thicker could be of benefit for when you are doing some of that spirited driving
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  9. #9
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    Quote Originally Posted by 504-504-504 View Post
    Not sure if its of any relevance but I avoid full lock on power steering equiped cars.
    Maybe hit full lock then back off a bit.
    Don't like the sound of the pump as it builds up pressure trying to move the immovable.
    Can't be doing anything good.

    Paul.
    It's a bit counter intuitive but that hissing sound on full lock is actually the pump bypassing pressure at full lock.

    The pump is pretty much just free wheeling once it's on full lock.

  10. #10
    1000+ Posts jo proffi's Avatar
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    Quote Originally Posted by jaahn View Post
    Hi
    Are the seals you fit correct seals for this application. 'Normal' seals are not rated for high pressure or sliding rod sealing. Perhaps look into the type of seal you are being supplied ??
    cheers Jaahn
    I guess so. Have always left the rebuild in the hands of professionals.

    Apparently it has more robust nissan rack seals in it, but thats about all I know of it.

    Jo

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    Icon14 Hope you solve this one ....

    Damn, I was counting on your guy to solve the seal replacement inevitability problem of aging Fuego's before mine need eventual replacement. I have a power steering unit I acquired with a busted seal to practice on when yours had survived long enough in service.

    Back to square one !!

    Will have to keep my fingers crossed, mine doesn't fail, though I have a spare power steer Fuego ready to go if it causes me grief.

    Good luck in solving the longevity issue Nigel. So happy to see both you and Mistarenno doing and trying new things, breaking new ground - Fuego world is in good hands.

    Ken

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    Budding Architect ???? pugrambo's Avatar
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    is it a powered rack or just a cylinder assisting the rack ?
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  13. #13
    1000+ Posts jo proffi's Avatar
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    Powered rack

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    Budding Architect ???? pugrambo's Avatar
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    Quote Originally Posted by jo proffi View Post
    Powered rack
    ok

    if it's blowing the seals out then your pressure relief valve is set too high or the seals in the rack are aged

    is the pump and rack original or like many over the years have you used a different pump from some other vehicle ?
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    Quote Originally Posted by mistareno View Post
    It's a bit counter intuitive but that hissing sound on full lock is actually the rack bypassing pressure at full lock.

    The pump is pretty much just free wheeling once it's on full lock.
    Could be vehicle specific as the Rodeo I have will squeal its belt at full lock, so pump not free wheeling there.
    Paul.

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    Budding Architect ???? pugrambo's Avatar
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    Quote Originally Posted by 504-504-504 View Post
    Could be vehicle specific as the Rodeo I have will squeal its belt at full lock, so pump not free wheeling there.
    Paul.
    change your oil, or the relief valve is starting to play up

    this is of course being that your belt is the correct tension
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    Quote Originally Posted by mistareno View Post
    It's a bit counter intuitive but that hissing sound on full lock is actually the pump bypassing pressure at full lock.

    The pump is pretty much just free wheeling once it's on full lock.

    Hi ,
    I'm no expert here but I doubt this is true for older racks. The hissing sound is the relief valve blowing at max pressure.
    As has been suggested the relief valve setting could be high or perhaps you could just set it lower anyway. Shim the spring holder or "adjust" its pressure as necessary. You will not notice the extra effort till it's a bit harder to park Most times the pressure needed is very modest so it will be ok on the road and the parking effort will give more feedback. Practice backing with a trailer to get better
    jaahn

  18. #18
    1000+ Posts 504-504-504's Avatar
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    The oil in the Rodeo's power steering system is fairly fresh, it blew a hose a while back.
    The power assistance in this vehicle is way too much, steering too light.
    205 Si has heavier steering with nice feedback and feel.

    Paul.

  19. #19
    1000+ Posts jo proffi's Avatar
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    Quote Originally Posted by pugrambo View Post
    ok

    if it's blowing the seals out then your pressure relief valve is set too high or the seals in the rack are aged
    Ok, how do I check the pressure relief valve??
    I think the seals are (were) good.

    Jo

  20. #20
    Budding Architect ???? pugrambo's Avatar
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    you need to find out what pressure the relief valve is set to and then find out the same for the original one

    put a guage on the line to test the one in the car but you need to know what the original system pressure was to work out if the new one is running at a higher pressure
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  21. #21
    1000+ Posts jo proffi's Avatar
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    This last few month have been a mild saga to say the least.
    ATF everywhere, and soaked into the exhaust wrap. smelly and smokey.

    One failed rebuild.....
    I think that was my fault by not being fussy enough about filtering.

    Then a second rebuild and a complete re design of the return line in 1/2 inch pipe/tube, and an inline filter mounted along the way.

    I got the steering mob to test my pump and it came back testing OK, with normal pressure for a nissan pump and certainly far less than the test rig they used to test the fuego rack.

    I am starting to suspect there is one nasty little culprit that i hadn't given much thought to.....Heat.

    The OE fuego PAS system has no cooling and the R25 system has a token effort towards cooling, but I'm going to go nuts and fit a proper cooler.

    There is plenty of realestate in the front of a fuego, so next step is to find a smallish auto transmission/power steering cooler with 1/2 inch lines to try and cool things down a bit.

    Jo

  22. #22
    1000+ Posts Wildebeest's Avatar
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    Prior to re-assembly polish the rack rod with a nylon kitchen scouring pad. When assembling seals over the rack lay a strip of electrical tape lengthways over the teeth to prevent damage on assembly. Lube parts with ATF to aid assembly.

  23. #23
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    Icon14 Pas pump Factory manual pressure testing procedures

    Jo
    According to the American I.S. note 12E
    Power Steering diagnosis and Service updates the complete overview is.
    1.Diagnosis
    Pressure testing the system
    Connect pressure gauge Fre, 214-04 to the high pressure hose as follows;
    1. Disconnect the High pressure hose from the pump.
    2. Install adapter Dir 803 in the pump fitting and reattach the high pressure hose to the adapter.
    3. Connect pressure gauge 214-04 to the adapter.
    Pressure Test Procedure
    Note: Be sure power steering fluid level and pump belt tension are correct before pressure testing.
    Start and run engine until it warms up.
    With the engine running at idle speed, place steering wheel in strauight ahead position and note gauge reading. Pressure should be 5 bars (72 psi) bujt not over 7 bars (102 psi)
    Turn the wheel to full left-turn position against stop and note gauge reading. Pressure should be at least 50 bars (725 psi) but not over 65 bars (943 psi). Pressure should also not differ from side to side by more than 5 bars (72 psi) and the gauge needle should not fluctuate.
    CAUTION: Do not hold the steering wheel in a full-turn position for more than 5 seconds as pump damage could occur.

    Pressure test diagnosis

    Straight ahead
    Test results Pressure below 5 bars (72 psi) probable cause
    1. Worn pump housing, rotor or vanes
    2. Flow control valve malfunction

    Test results Pressure above 7 bars (102 psi) probable cause
    Pump flow control valve sticking

    Full left or right turn
    Test results Pressure below 50 bars (725 psi) in both positions probable cause
    1. Worn pump housing, rotor or vanes.

    Test result Pressure above 65 bars (725 psi) in both positions probable cause
    Pump flow control valve sticking
    Test result Pressure normal in one position but low in opposite direction
    Pump flow control valve malfunction.

    Straight ahead or full left/right turn position
    Test results Pressure below 5 bars (72 psi) and test gauge needle fluctuates rapidly
    Flow control valve sticking.

    Test result Pressure below 5 bars (72 psi) and the test gauge needle is steady
    1. Flow control valve malfunction
    2. Internal leak in steering gear

    Steering Gear oil leak diagnosis

    Start engine and turn steering wheel to full right and then full left turn
    If oil leaks from end of power steering at A (Fig. 1) Replace steering gear.
    If oil leaks from rotary valve end of gear at B (fig.1)
    Stope engine disconnect power cylinder lines from rotary valve housing and plug housing fitting 1 and 2
    Then start engine and turn wheel to full right turn then full left turn
    If oil leaks from rotary valve end of gear B (fig.1) then replace rotary valve bearing and seals or replace valve if valve rings are worn.

    Alternatively If oil does not leak from rotary valve end of gear. Replace steering gear.

    2.Steering Rack and Pinion Removal/Installation

    When removing the steering rack on models with air conditioning, it is necessary to remove the receiver drier attaching screws. This allows the AC hoses to be lifted high enough for the steering rack and pinion to pass underneath during removal. Add this information to the steering rack and pinion procedure on page G39 of the MR 220 manual and page G40 of the MR 238 manual.

    After steering rack installation , be sure to bleed the power steering system and check toe out. In addition , also check steering box height setting on Fuego models. Add this information to the steering rack and pinion installation procedure on Page G-40 of the MR 220 Manual and page G-41 of the MR 238 Manual.

    3.Plunger adjustment

    Tighten the Plunger adjustment adjusting nut to 10 N.m (8 ft lbs plus or minus 1 foot pound) torque
    NOTE Plunger adjustment must be performed with the steering rack mounted in the vehicle and with the engine stopped (no pump pressure during adjustment)
    Record the adjusting nut torque and plunger adjustment information on page G-41 of the MR 220 manual and Page G-42 of the MR 238 manual.

    4.Rotary valve seal and bearing replacement

    Disassembly

    1. Remove the rotary valve housing to steering gear bolts and remove the valve and housing.
    2. Remove snap rings 1 & 2 (Fig, 2)
    3. Tap rotary valve 7 out of the bottom of the housing with a brass or fibre faced mallet.
    CAUTION: Do not force thevalve out. The valve seal rings could be damaged.
    4. Remove seals 3 and 4.
    5. Remove bearing 5 and seal 6, use air tool T.Ar.65 to remove bearing and seal (Fig. 3)

    Cleaning and inspection

    Clean and dry the housing and valve with clean solvent and compressed air.
    Inspect the valve assembly. Replace the valve if the pinion teeth or bearing surfaces are damaged or if the valve seals are cut, cracked, or torn. Polish the housing bore with crocus cloth to remove any light corrosion or minor surface irregularities.

    Assembly

    1. Coat valve surfaces A and B with Molycote 33 medium grease (Fig.2)
    2. Install seal 6 and bearing 5.
    3. Lubricate thevalve seal rings and housing bore with power steering fluid and install the valve in the housing.
    4. Install seals 3 and 4 and snap rings 1 and 2.

    Record the rotary valve seal and bearing replacement procedure on pqage G-42 of the MR 220 and MR 238 manuals

    5.Power Steering Pump Pulley Replacement

    1. Remove pulley with tool Mot. 49 (fig 4)
    2. Press the replacement pulley onto the pump shaft as follows (Fig 5)
    a. Start the pulley on the shaft
    b. Thread an 8 inch length of 3/8th 16 threaded rod into the pump shaft.
    c. Place - inch drive socket over the threaded rod and onto the puley.
    d. Place a 7/16th , then a 3/8th flat washer over the rod and on top of the socket
    e. Thread 3/8TH -16 hex nut onto the rod Align the socket on the pulley and tighten the nut to keep the socket to keep the socket in position
    f. Install two more 3/8 16 hex nuts onto the rod. Run the nuts about half inch down from the upper end of the rod and tighten them against one another securely. These will serve as jamb nuts.
    g. Put a wrench on the two jamb nuts to keep the threaded rod from turning and tighten the nut on top of the socket to press the pulley onto the shaft

    NOTE Press the pulley onto the pump shaft until the end of the shaft is flush with or about 1/16th inch above the pulley boss.
    Record the pump pulley replacement procedure on page G-54 of the MR 220 manual and page
    G-50 of the MR 238 manual.

    I will try and post up images of the Figures 1 to 5 if needed I think Bob previously posted up PDF images/links for those manuals, but I might be wrong.

    I tried to post this as a PDF, but just exceeded the site limit, I hope the formatting is o.k. and the information helpful, if you need the five image figures I will copy and add.

    Ken

  24. #24
    bob
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    G'day Ken,

    I think that the system allows more file grunt if you add it as a ZIP, or it used to

    cheers,
    Bob

  25. #25
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    Icon12 Thanks bob, cut and paste was easy!!

    Quote Originally Posted by bob View Post
    G'day Ken,

    I think that the system allows more file grunt if you add it as a ZIP, or it used to

    cheers,
    Bob
    Yah mean I have to do a Rudd and ZIP!

    To old to change my ways, and the info may be old hat and not needed!! Haven't zipped for years other than after pointing percy!!

    Thanks mate!
    Ken

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