Problem with RV power steering and brakes.

Discussion in 'Domestics' started by nickb2, Jul 15, 2017 at 10:40 AM.

  1. nickb2

    nickb2 Wrench. I help when I can

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    MAKE:pace arrow
    MODEL: Class "A" 37j
    YEAR:1994
    MILES:???
    ENGINE: Methinks a 454.
    DESCRIBE ISSUE....

    Loss of power steering and brakes when put into gear.

    We have at the shop at this time this RV and it has been there for the past two weeks or more. Client is irrate, the Tech working on it is irate, my boss is irate and they have now asked me to look into it as I am bi-lingual and often flaunt that I am a proud member of Bat auto.

    So, here is what the other tech has done..

    He replaced the hydro boost, the power steering pump. New (rebuilt) hydro boost leaked, so another one was installed, same problem, but no leak.

    PS pump whines like a bitch once put into gear. Also whines like a bitch once brakes applied in gear.

    After being stumped, my co-worker came to me to ask to help him bleed the system. I noticed it bleed better in neutral and whine went away. In park, bleed was not as good. Once the engine is turned off, the fluid spills out the reservoir like no tomorrow.

    Thursday, we had almost got it perfect, I mean almost. Boss goes to drive it around town, came back saying steering went stiff again and loss of brake boosting. Mind you, kind of alarming with a class A RV to say the least.

    So I did some research and found that this unit has a HR-1 relay valve. I also found two bleeding procedures. One is in fact to bleed the unit engine running in NEUTRAL. Which is also what I found worked better.

    Here is a copy paste of a link I found describing EXACT same issue. Plz take time to read it and give me your thoughts if you are so inclined. What are we missing here? My next step is to tell my boss to get a new HR-1 relay valve. That is the only thing I can see at this point.

    https://www.justanswer.com/rv-motorhome/5lv9i-1993-pace-arrow-chevy-chassis-454-engine-power.html
     
    Last edited: Jul 15, 2017 at 10:47 AM
  2. nickb2

    nickb2 Wrench. I help when I can

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    I didn't know if this went into the heavy equipment forum, but thought it more suitable for the domestic forum as it is a chevy chassis. Maybe an admin can decide which is better, but for now I am going for the domestic forum.

    Again, thx to any one for any ideas.
     
  3. billr

    billr wrench Staff Member

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    Hydro-boost with a 454 gasoline engine? What an annoying way to make two simple systems (PS and PB) complicated. I'll have to study that quasi-schematic in the link; any chance there is a better one? Obviously, I know near-nothing about this vehicle or system, but will try to help with "general purpose" ideas.
     
  4. nickb2

    nickb2 Wrench. I help when I can

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    Thx bill, here are a few more schematics I was able to find without paying for the whole service manual. In the following link, we see better the relay valve that seems to be the issue.

    https://www.justanswer.com/rv-motorhome/2c6qw-1991-pace-arrow-33-motorhome-454-engine.html

    My understanding is that this HR-1 relay valve unit is probably faulty seeming as it interacts directly with the parking brake hydraulic system. Hence maybe why it is overflowing once engine is turned of. A stuck valve maybe letting the reserve fluid pass back through the fluid reservoir. I read somewhere that this vavle actualy permits to have residual pressure for a few seconds once the engine is turned of, so my thought is that is what is causing our root issues. And the first link I linked seems to confirm that as the guy did say, that if we are sure the system is bled properly and system is still not functioning, most likely a relay valve.

    There are two reservoirs. One for the power steering pump which can be check as any normal vehicle with a depth gauge, and another for the power brake assist assembly underneath the truck which has the actual bleeder that is used to bleed the system in neutral engine on.
     
  5. billr

    billr wrench Staff Member

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    I have grandchild duty today, will try to study later.
     
  6. nickb2

    nickb2 Wrench. I help when I can

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    Yeah, no nude chics things. LOL. On the other thread, yeah, I was 10 over, so your right, no fear for that, but still, a concern. Have fun with the kid. Granfathers are the best.

    Although I do not wish to be one soon, my son will 14 soon, so that may be in the next decade or so.
     
  7. jd

    jd Hero Member

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    Wondering if somebody on the Class A or Tech Issues forums could help you. gOOgle "rv.net auto park." Or there are "Chassis Clubs" on the IRV2 Forum. I got a few hits on gOOgle "irv2 auto park" and one of those might help. I was only part way through your text when I thought "Oh No Auto Park!" Somebody may be able to help, will likely want the Model of this Chassis, like P30 (Chevy), W32 (Chevy sold as Workhorse).
     
  8. dabunk

    dabunk wrench

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    This is the exact same system used on school busses made by Chevy of that vintage. Have not run into that same problem that I recall but will check with some friends and see what they say.
     
  9. dabunk

    dabunk wrench

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    As I recall there were 3 or 4 different units for that vintage all looked alike but were different had to order by vin
     
    Last edited: Jul 15, 2017 at 7:30 PM
  10. dabunk

    dabunk wrench

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    Also one of my buddies asked if when you were purging the air did you have the front wheels off the ground? We always did that with our buses as well. Is the PS fluid aerated at all?
     
  11. nickb2

    nickb2 Wrench. I help when I can

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    Yes, I purged off ground and 40 ton jacks off rv.

    Like I said before, I inherited this from irate boss and co worker. I like the ideas back and forth, it keeps me grounded.
    Yes, the fluid is like foam from the sea.
     
  12. jd

    jd Hero Member

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    What we need to know, is: "What's Making the Fluid Foamy?" I know we are not supposed to take Brake Fluid that has been "Bled" through the bleeder valves, through the piece of hose, and caught in the Coke Bottle. That process is claimed to add air bubbles that make the fluid compressible. What I don't know, is: "Does same apply to hydraulic oil like transmission and power steering fluid?"
     
  13. billr

    billr wrench Staff Member

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    I'm kind of thinking like jd... how is it getting foamy, why is the reservoir puking when you shut it off? I don't think bleeding is the problem. Hydraulic systems with a pump usually self-bleed fairly quickly. I think that pump is sucking air somehow.

    A wild thought: did the 454 ever have reverse-rotation accessories from changing from V-belts to serp belts?
     
  14. nickb2

    nickb2 Wrench. I help when I can

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    No this engine has only v-belts and nothing was changed. The system has a bleed screw much like a brake system. It sit atop the fluid reservoir of the park brake actuator as seen in following snapshot. Read paragraph that starts with "with the shift selector in park" Screenshot (87).png
     
    Last edited: Jul 16, 2017 at 5:28 PM
  15. billr

    billr wrench Staff Member

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    No help to offer, but is there no accumulator in this system to provide a stop or two if the engine /belt/pump fail?
     

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