Hydraulic Steering Design and Leak

Discussion in 'Boat Design' started by papabravo, Sep 14, 2014.

  1. papabravo
    Joined: Sep 2012
    Posts: 22
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    Location: Northern Virginia

    papabravo Junior Member

    Boat was built in 1972, Finland. I have no manuals. No maintenance records.

    Situation:

    1. Low (no) fluid: Steering system is operable, but has a slow leak. Needs fluid. But which? All I can tell you is the old fluid was red. I didn't taste it like the old-timers do--so I offer no insights there. What fluid is best to follow a fluid that you didn't know what is was?

    2. Fixing the leak: From what I can tell, the leak is NOT at the ram cylinder. Check photos, the cylinder mount is clean and dry. On the other hand---the leak appears to be at the rudder post ?!? (see pics).

    Why does steering fluid run to the rudder post? You can see from the pics the leak is there. Tthat spirally white-thing in rudder-post-2.jpg is actually a tube with steering fluiid in it. ...and where the steering fluid goes once it's embedded into the fiberglass hull.... I'm stumped.

    Another forum suggested the rudder post may get a shot of steering fluid to cope with extreme cold...maybe.

    Plan A, is fixing the leak, and understanding how the design works.
    Plan B is to keep filling the fluid, and cleaning it up.
    Plan C is to decommission the fluid connections at the rudder post (bad idea)

    I like plan A -- but am not sure I can fix it.

    Ideas?

    Thanks.

    PB
     

    Attached Files:

  2. FAST FRED
    Joined: Oct 2002
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    Location: Conn in summers , Ortona FL in winter , with big d

    FAST FRED Senior Member

    In that era ATF (automatic transmission fluid)was a common fluid for many l hyd systems .

    The usual leak is caused bt a failed seal.

    Take the unit off , give it to a place that repairs hyd in trucks , earth movers etc , and they can easily fix it.

    So much ,,,strange,,, hyd items come thru most shops that their stock catalogs can locate what ever is shot ,simply from its measurements.

    Since its not a boat shop, repairs are usually fair priced ,,inexpensive.
     
  3. Poida
    Joined: Apr 2006
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    Location: Australia

    Poida Senior Member

    If it is red, it may be brake fluid and may have been filled by a past owner and not used the correct oil.

    Find a manufacturer of a comparable system and see what fluid they use, drain your system and replace it with the correct (if necessary) fluid.

    Leaks, you will have to completely clean the area and run it and search for the source of the leak. As Fast Fred says usually a seal, but depending on your capabilities, you may be able to replace them yourself, they are normally fairly cheap unless the manufacturers have had special seals made so you have to buy theirs, may be expensive.

    You can take it to a repairer but be prepared to be told the cylinder needs replacing or built up and re-machined.

    The cylinder looks like it has Banjo fittings, I hate those and I replace them with screwed fittings when they start to leak.

    Other than that, good luck.

    Poida
     
  4. AndySGray
    Joined: Jun 2014
    Posts: 296
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    Location: Cayman

    AndySGray Senior Member

    I'm with fast fred, ATF (automatic transmission fluid) is common as a steering fluid and seastar/teleflex still recommend it as a backup if you can't find their special 'own brand' stuff.

    I've done a quick diag of how the cylinder works which might make it clearer which seal has gone.

    Fluid enters the cylinder through the banjo bolts at A or B - can't get past the seals at D so it pushes the piston and the shaft along the bore and forces fluid out the other side at B or A respectively. If the seals in yellow C are worn then the fluid will also escape and run allong the shaft. Dismantling is easy IF the four long bolts move and ALL the seals can be replaced as per Fast Freds suggestion. You will have to remove the Banjo Bolts and drain the system but this is expected maintenance every 5-10 years and not as hard as first appears.

    I don't think your curly wotsit is actually anything like what you think. It is essential to electrically bond the rudder and post together or it will cause galvanic corrosion - this is likely just a plain wire (but your seals have been leaking for a while and the voids between the wire strands are full of ATF) and the other end will be clamped to the rudder tube at the bottom - someone has fibreglassed it in but the 'curl' is just there as the tube is stationary and the rudder stock moves.

    So there you have it - plan A ;)
     

    Attached Files:

    Last edited: Sep 14, 2014
  5. AndySGray
    Joined: Jun 2014
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    Location: Cayman

    AndySGray Senior Member

    The bolt/pivot between the ram and the rudder stock will likely have a cotter or split pin which if you don't know that, turns it into a pig of a job.

    You may get away with removing the two big screws at the other end rather than unbolting the whole end by undoing the 4 coach bolts. once the cylinder is free then you can do the banjo's but have something to catch the fluid, try not to move the piston - will force/pump fluid out and it always goes in your face (murphys 12th law). Re-use the old banjo bolts if you will, BUT ALWAYS new copper washers.

    Those banjo bolts's are not the common ones - they have a bleed nipple on them and while you should look at poidas suggestion of changing it may not be as practical as first look as you will have to make provision to bleed too.

    Should be out of the boat in less than an hour but have a change of clothes handy.

    :p
     
  6. papabravo
    Joined: Sep 2012
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    Location: Northern Virginia

    papabravo Junior Member

    Thanks Andy. Your comment that the leak is running along the shaft was an "a ha" moment for me. That explains why the cyclinder mount is mostly clean and dry, and the rudder post is covered in hydraulic fluid.

    Your diagram helped.

    Now to fix. Which will be hard because the space is very confined.
     
  7. AndySGray
    Joined: Jun 2014
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    Location: Cayman

    AndySGray Senior Member

    Cracking a cold one and wishing you the best of luck ;)

    Been there, done that, got the T-Shirt, got the red oil all over the T-Shirt, thrown T-shirt away and got in the shower with a tub of swarfega and a gallon of simple green... :D

    I estimated an hour for 5 bolts for a reason.

    Personally prefer to do the hydraulic fittings last or it ends up messier than the fairground contest to catch the greased pig...

    There's never a lanky young relative in need of some 'character building' (euphemism for unpleasant) boating experience when steering rams are to be changed.
    :confused:
     

  8. papabravo
    Joined: Sep 2012
    Posts: 22
    Likes: 1, Points: 0, Legacy Rep: 11
    Location: Northern Virginia

    papabravo Junior Member

    LOL.. you made me google "Swarfega."

    May be the equiv. of US "D&L Hand Cleaner." I'm not sure they make that any more..
     
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