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Technical How to increase pressure on a PS pump???

Discussion in 'The Hokey Ass Message Board' started by CarQuestions, Sep 4, 2015.

  1. CarQuestions
    Joined: May 24, 2015
    Posts: 97

    CarQuestions

    I have installed power steering in a 1949 Packard and the PS system makes a loud buzzing noise at low speed (like parking).

    The actuator is an externally mounted Monroe hydraulic ram rod.

    The PS pump I used was out of 1953 Chrysler Imperial (it is mounted on the back of the 6V generator). The power steering pump had a reservoir that says "Purilator" on it so perhaps that was the vendor that was used by Chrysler however the pump has stamped Eaton so at some point the pump was replaced with a non-OEM replacement pump. The Chrysler manual states that it should put out 650 PSI max when the steering wheel is turned to the stops and I checked it with a pressure gauge and ball socket valve and it puts out EXACTLY 660 PSI and the pump makes the same noise (but less loud).

    The Packard manual states that two different PS systems were used and the Bendix system used a pump that was 650 PSI (just like the Chrysler) and the Monroe system needed 950 PSI or "loud steering actuator noises and erratic steering will result". The pumps identical however a different pump relief spring was used.

    So I think I can fix this problem by installing a new pressure relief spring.

    Does anyone have any knowledge on this subject they can type my way???

    Any help would be GREATLY appreciated!!!

    Bill
     
  2. You are exactly right, just change the pressure relief spring. Those early power steering pumps were nothing more then simple constant displacement hydraulic gear pumps. The only way to control the pressure was with the relief valve.
     
  3. CarQuestions
    Joined: May 24, 2015
    Posts: 97

    CarQuestions

    Does anyone have any experience with the Eaton 5H pump? I added three washers to the pressure relief spring and it bumped up the max pressure output of the pump to 1000 PSI and that was good however the low side pressure output is still only 150 PSI and the PS system still humms (growls) when turning the steering wheel at low RPM. It is quiet at idle and at low speeds however when it is really needed (like parking) it is really noisy.

    Does one need to change the valve and the spring to get it to produce good low need pressure (like 400 PSI) and then it can bump up to 1000 PSI when really needed?

    Any help would be greatly appreciated!!!
     
  4. with the car jacked up and the motor off. how does it steer? i recently went through a power steering problem on a ford with all new parts, the previous owner could not get the power to work despite changing all the parts. i found the "rebuilt" steering box was not adjusted correctly. the worm bearing adjustment was too tight. so the power steering, even tho it was working it felt hard.
    don't know if that is your problem, just thought i would throw it out there.
     

  5. CarQuestions
    Joined: May 24, 2015
    Posts: 97

    CarQuestions

    Thanks Tb33 for your suggestion Good thinking..

    I did check the adjustment of the steering box. It is smooth and when the front wheels are off of the ground the steering (engine off or on) is very smooth and you can spin the steering wheel and it spins freely (like nothing is attached to the steering shaft).

    I need to figure out how to increase the pressure out put of the PS pump.
     
  6. bonzo-1
    Joined: Oct 13, 2010
    Posts: 336

    bonzo-1
    Member

    You need more RPM at idle. Change the pulley size. Then take those washers back out of the relief valve so you done blow something out.
     
    tb33anda3rd likes this.
  7. CarQuestions
    Joined: May 24, 2015
    Posts: 97

    CarQuestions

    >You need more RPM at idle. Change the pulley size.

    Good thinking...I did raise the engine idle while turning the steering wheel and that did not make any difference.

    I installed a test gauge and valve in the supply side power steering hose and I could see that the pressure in the supply hose will increase to 650 PSI and stop at 650 PSI during turning and the hum would start so I can confirm the noise is the pressure relief valve unseating (almost same noise as when the steering wheel is cranked against the max turning limit) so it looks like I need to increase pressure.
     
  8. Not to change the subject but sometimes they growl ( buzz???) when there is air in the system.
     
  9. CarQuestions
    Joined: May 24, 2015
    Posts: 97

    CarQuestions

    >Not to change the subject but sometimes they growl ( buzz???) when there is air in the system.

    Good info. I bled the system and have also looked inside the reservoir with a flashlight and no bubbles...I was hoping that was the case....
     
  10. Well you are ahead of the game.

    Just to keep you on your toes.

    If you top it and use ATF like most people don't use Type F ATF. If it didn't buzz before hand it will afterward. Just file this under general education to the general public that will read your thread.
     
  11. Truckedup
    Joined: Jul 25, 2006
    Posts: 3,975

    Truckedup
    Member

    You may need a bigger ram diameter ....Is the steering feel like a 50's Mopar or does it have some resistance to turning?
     
  12. CarQuestions
    Joined: May 24, 2015
    Posts: 97

    CarQuestions

    >You may need a bigger ram diameter ....

    Hmmm...is that an insult or something?!?!?!

    : )

    >Is the steering feel like a 50's Mopar or does it have some resistance to turning?

    I do not have any experience with a 50s Mopar steering system however there is some resistance at very low speeds such as parking (when driving it is like "Pinky Finger Steering" and when parking it is more like "three finger Steering") so I believe the pressure is not sufficient to help with the steering assist.
     
  13. CarQuestions
    Joined: May 24, 2015
    Posts: 97

    CarQuestions

    Thanks...I used Dextron III ATF.
     
  14. Truckedup
    Joined: Jul 25, 2006
    Posts: 3,975

    Truckedup
    Member

    Your system might need more mechanical advantage so a larger diameter ram will give more "push" at the same PSI...But if the pump doesn't have enough volume you may run out of power assist when the steering wheel is turned rapidly...The only way to know is to try it..
    Early Mopar PS is like way too easy and no feel...Well, the rest weren't much better.
     
  15. I had an issue with a ram style power steering system making similar noises, Changed the fluid to dedicated old car power steering fluid from ATF, noise went away.
     
  16. CarQuestions
    Joined: May 24, 2015
    Posts: 97

    CarQuestions

    >Changed the fluid to dedicated old car power steering fluid from ATF, noise went away.

    First I tried regular Power Steering fluid and it had this same noise...then a lot of people on this forum and the PS pump rebuilder told me to go with Dextron and I switched to Dextron III and still have the same noise.
     
  17. Dan Timberlake
    Joined: Apr 28, 2010
    Posts: 1,303

    Dan Timberlake
    Member

    On some rack and pinion cars "bleeding" can require slowly turning the steering wheel full left to full right about 20 times with the front jacked off the ground.
     
  18. Two shabby
    Joined: Jun 29, 2015
    Posts: 29

    Two shabby
    Member

    is the fluid in the reservoir turbulent at idle? If it is, you may have a clogged screan or filter in the reservoir. it has a screen or filter that is. I guess you have had the lines off already when you installed it. I have seen weird stuff get into power steering lines and cause a partial clog.
     
  19. CarQuestions
    Joined: May 24, 2015
    Posts: 97

    CarQuestions

    >is the fluid in the reservoir turbulent at idle? If it is, you may have a clogged screan or filter in the reservoir.

    Good thinking. The filter and lines are new. There is no bubbles in the reservoir.

    I need to figure out how to increase the pressure output of the pump.
     
  20. Engine man
    Joined: Jan 30, 2011
    Posts: 3,476

    Engine man
    Member
    from Wisconsin

    It sounds like you have the relief valve pressure high enough but not enough flow at low rpm to get to that pressure. With the pump driving off the generator, it might be difficult to turn it faster at idle depending on your pulley setup. I assume the generator and water pump run on the same belt. Putting a smaller pulley on the generator might lead to belt slipping and you could turn the generator too fast at higher rpm. You probably can't change the pulley on the engine to a larger one and put a larger pulley on the water pump. You might have to use an independent power steering pump.
     
  21. Engine man
    Joined: Jan 30, 2011
    Posts: 3,476

    Engine man
    Member
    from Wisconsin

    Is there any pressure adjustment on the control valve that is connected to the pitman arm?
     
  22. All the talk of psi,what about the flow rate of your pump opposed to the flow rate of your power assisted steering cylinder.Does the Packard cylinder suit the flow rate of the Chrysler Pump?
    Are you hearing a relief noise or a cavitation noise=pump not keeping up with cylinder at low revs?
    What is your line pressure like at idle turning left to right?
    Just a thought.
     
  23. CarQuestions
    Joined: May 24, 2015
    Posts: 97

    CarQuestions

    WOW...VERY GOOD thinking on this!!!

    >Does the Packard cylinder suit the flow rate of the Chrysler Pump?

    I have literature that says the Chrysler pump puts out 1.9 gallons per minute however I do not have any literature on the Packard pump output (Service Manual does not say).

    In addition to the Pressure Relief Valve, there is also a Flow Control Valve in the Chrysler pump that has both an orifice and a spring. The operation on this is that when the flow of oil through the (orifice hole) reaches a preset level, the oil flowing through this fixed orifice will begin to back up and then this will create back pressure that will push against the oriface shoulder and this pushes against the spring. When the Flow Control Valve moves a small distance it will uncover a port that allows the fluid to return back to the input port of the pump thus limiting the flow of oil to the actuator.

    Hmmm...I did not add any shims to the flow control valve spring. This might be the ticket. I might add a couple of shims (washers) to the Flow Control Valve spring to stiffen it up and then it will not limit the oil flow until a higher amount of gallons per minute.

    Naturally I have no way to measure GPM...only pressure. I guess the way to do this is to watch the pressure gauge (while someone is inside the car turning the steering wheel) before I take it apart again and then add the shims and watch the pressure gauge again. If the gauge needle increases while the steering wheel is being turned and then fluctuates when I hear the buzz that could mean that the FCV is bypassing.

    >Are you hearing a relief noise or a cavitation noise=pump not keeping up with cylinder at low revs?
    What is your line pressure like at idle turning left to right?

    I will have to connect up the gauge again

    I imagine the cavitation noise would be a function of low oil level however the oil level stays near its max level line. It does drop and rise just a bit however I think that is a function of the actuator piston being moved and one side of the piston has the actuator shaft and the other is a full piston head...however that is just a SWAG.
     
  24. CarQuestions
    Joined: May 24, 2015
    Posts: 97

    CarQuestions

    I stalled out on this project for a couple of weeks however I need to tear into it again.

    Does anyone know if I can increase the flow rate of the Eaton PS pump by increasing the Flow Control Valve spring rate by inserting some washers in between the pressure line fitting and the spring?

    Any direct experience would be greatly appreciated!!!
     
  25. Hnstray
    Joined: Aug 23, 2009
    Posts: 11,897

    Hnstray
    ALLIANCE MEMBER
    from Quincy, IL

    In the second paragraph above, you mention the Flow Control Valve......the orifice and relief bypass.
    Adding spring pressure could delay the relief bypass, but if insufficient flow is the problem, maybe the orifice should be larger to flow more volume with the current relief spring pressure. Or, a combination of both, increased orifice size and moderately increased relief spring pressure. I realize changing the orifice size could be risky without a spare Flow Control Valve assembly, but perhaps the idea presented can be researched before you make a 'commitment' to changing it.

    Ray
     
  26. Grahamsc
    Joined: May 13, 2014
    Posts: 466

    Grahamsc
    Member
    from Colorado

    Generaly speaking constant volume pumps only change flow rates with increased shaft speed.
    If a pump is built to put out 1 gallon per min at 1000 rpm it will never increase to 1.5 gallons at 1000 rpm only decrease over time with internal wear.
    A smaller pulley would speed the pump up changing volume.
     
  27. Engine man
    Joined: Jan 30, 2011
    Posts: 3,476

    Engine man
    Member
    from Wisconsin

    The flow control valve is designed to keep the flow rate constant at higher rpm so the steering doesn't get jumpy. Find a hydraulic repair shop. They will have a flow meter and could check or set up the pump for you. A flow meter costs around $300. A larger orifice would allow more flow before it builds up enough pressure to open the bypass.
     
  28. CarQuestions
    Joined: May 24, 2015
    Posts: 97

    CarQuestions

    I think we are on the right track with the orifice (hole) diameter and the spring.

    When I get a chance I will connect up my pressure gauge and then:

    1. Add a couple of washers to the spring to stiffen it up just a bit and see if that helps (I will do this first because it is essentially free and can be easily reversible).

    2. Drill out the orifice one step higher on my drill bits. This one I am hesitant to do because I will need to use leather of some other thick material to jam the valve in the vice without scratching the valves finish.

    I will take pictures and notify you of my progress. First I will need to get the car back from my dad. The last time I got it from him I had it for 5 months for an engine + trans overhaul and PS fabrication and he missed his toy.

    THANKS AGAIN!!!

    Bill
     

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