T&T: Hydraulic Steering Problem

[Steve Anderson]

<Steering has become very sluggish and slow.  What is the procedure for adding
and/or purging this system.>

Don-

Your system probably has three hydraulic lines - one each for port/starboard
and a third which returns the fluid to the helm stations.  Look around near
your steering ram.  Probably there is a small (5" X 6" X 1") metal block
mounted within a couple feet of the ram with two lines connected to the ram
and three lines on the other side. This is the Uniflow valve.  It should have
label on it that says Capilano Uniflow Valve Model 50.  It has check valves
and little pistons inside that respond to pressure differences and thus
controls and directs the flow of the hydraulic fluid.  They are very sensitive
to even minute amounts of dirt or grit.  (Capilano eliminated this valve and
the return line in the early 90s and its functions were incorporated into the
helm pumps themselves.  New helm pumps are model 1250 or 1275.  Older ones are
either 250 or 275.  Treat the Uniflow valve nice - they are no longer made and
it is almost impossible to get parts for them.)  On the edge of the valve is a
slotted screw that sits proud of the surface about 1/8".  This is a bypass for
either the port or starboard steering.  There is a second one on the opposite
edge that is probably hidden from view and is for the opposite steering
function of the first.  Open both screws about 1 1/2 turns.  Now, when you
turn either wheel the ram and rudder will not move because the fluid is
flowing directly from one helm line, through the Uniflow valve to the return
line, bypassing the ram.

Now, grab plenty of paper towels and go to the top helm pump and find the fill
port.  Put a tight fitting funnel in it and pour in ATM type II or III fluid
(assuming that's what's in there now) as you turn the wheel continuously to
starboard.  (As you do this, the fluid is moving in a continuous flow from the
upper helm pump, through the starboard line to the Uniflow valve, through the
bypass into the return line and back to the upper helm reservoir, carrying any
air along with it.)  Air bubbles will rise into the funnel.  Keep pouring and
turning until you see no more bubbles and can not add any more fluid.  This
will probably take 50+ turns.  Now turn to port as you add more fluid.  Now go
to the lower station and turn to starboard as someone else pours in fluid at
the upper helm.  Now do the same as you turn to port.  Now exercise your
autopilot in the same way.  You may have to repeat the cycle again.  Do it as
many times as necessary until no more bubbles appear and no more fluid can be
added.  Now go back to your Uniflow valve and close both bypass screws.  Check
the action of the ram/rudder.  It is possible that there is a small amount of
air in the ram and/or the lines between the ram and the Uniflow valve.  This
should not be a problem and any air will eventually work its way to the top of
the upper reservoir.  Use a pipe wrench or emergency tiller on your rudder
post to try and turn the rudder.  You should not be able to because the check
valves in the Uniflow valve should lock the rudder in position.  If you can
turn the rudder then you probably have grit in the check valve(s) and the
valve will have to be removed and cleaned.  If you need to do this then get
back to me.

When I was having steer problems on my 87 Krogen I drained out all the fluid (
it was regular hydraulic fluid, not ATM) and found  it to be black with
residue.  As I said, the Uniflow valve is very sensitive to dirt and your boat
is 3 years older than mine so you may want to drain the fluid and flush the
entire system several times with diesel until the diesel comes out the same
color it went in.  Then refill with ATM and bleed the air out as above.

Good Luck-



Steve Anderson
"Intrepid"