How to replace hydraulic steering hoses and refill the system with fluid

In April I decided it was time to get the outboard engines serviced and a stopcock changed, on the advice of the surveyor, for which she’d need to come out of the water. I arranged to take her 500m to the Harbour, on a Friday evening. As the boat floated off the mud I started the various checks and noticed that the steering was very light.

Further examination revealed no movement of the engines when the wheel was turned.

Looking at the hoses it became apparent that there was a hole in one where someone had put a right angle bend and a cable tie. There was a further cable tie holding the hose in position. This resulted in excessive flexing of the hoses with cracking of the outer core exposing the wire reinforcement that rusted away. The loss of strength once this had occurred meant rupture of the hose was inevitable. Fortunately I was able to get a tow to the waiting berth.

There’s a right angle bend in the flexible hose near the cable tie – and that proved a weak spot under constant movement when the boat was being steered

After removal the hole is clearly seen along with the rusted ends of the wire reinforcement. The lower hose also shows rust staining indicating that its inner core was deteriorating as well

I asked several boatyards about replacing the hoses, but nobody was available at the time so it was down to me. With patience and lots of viewing of ‘how to’ videos it turned out to be fairly straightforward..

Replacement oil was also needed. MAnufacturer are very specific about the oil (ISO 22) you should use. The nearest shop could supply this, but only in five gallon drums – far too much for my needs. I tried all the nearby chandlers but, although they had oil for a steering system, it was the wrong specification. So it was online to a well known auction site where I found exactly the right oil in a 5lt container – still too much but some spare wouldn’t go amiss.

I carefully marked the connections and once I’d removed the hoses I took them to the shop. They suggested that instead of fabric covered, wire reinforced tubing I instead use nylon hoses that wouldn’t suffer the same problem. Stainless steel connectors were not in stock, but were ordered for the next day. In addition, I bought a screw-in spigot for the oil reservoir and a right angle connector to avoid a repeat of the problem.

How to inspect a hydraulic system

This failure made me realise that my steering system needs regular checking. The thought of it failing crossing the Bay, still fills me with horror.

  • Does the steering feel normal when you turn the wheel smartly from side to side? If it feels ‘notchy’ air may have got into the system.
  • Do twin engines move at the same time? Overly light or heavy steering may warrant further investigation before taking the boat out to sea.
  • Check the oil level in the reservoir. Oil doesn’t evaporate and if the level falls there’s a leak.
  • Carefully check all hoses, seals and connections both inside and outside the boat for wear or deterioration. Cracking and/or discolouration may indicate that failure is imminent.
  • Remove the cap from the reservoir and check the colour of the oil. It should be clear and almost the same colour (may be slightly darker) as when it was put in. If it’s black, the oil has deteriorated, so the cause should be found and rectified and then the oil changed. If it’s milky then water is getting in.
  • Check the steering ram to ensure none of the fittings are loose, that it moves without hindrance and that there are no leaks from any of the seals.

1. Before removing anything mark it up and photograph where it all goes. Here you can see the back of the steering pump and the old hose connections. I carefully pulled the hoses through from the stern, having first attached mousing lines to each so the new ones could later be pulled back along the same route.

2. The new hoses were marked up to match the old ones, and the ends were taped to stop any debris getting in. The hoses were then attached to the mousing line with a sliding hitch that was also given a protective layer of tape, and finally some cable ties provided extra security to ensure the line stayed attached to the hose.

3. Both hoses pulled through with only a little difficulty with the tape, knots and cable ties still in place having done their jobs. The hoses were connected up at both ends guided by the markings copied from the original hoses. Care should be taken not to overtighten the connections.

4. Filling up the oil reservoir with a funnel would be messy so I bought a threaded spigot to fit into the filler hole on the reservoir and bought some clear plastic tubing to fit it.

5. Old washing up liquid bottles fitted the tubing and I punched holes in their bases to allow air in and the oil to run down when filling and bleeding the system. To bleed the system turn the wheel from port to starboard and back again, jerking it occasionally, until air stops coming out of the bleed valves at the steering ram at the stern.

6. Bleeding the system from both the port and starboard bleed nipples at first produced black oil that was obviously way past its best.

7. The one-way valve in the tube system stopped working so in the end I used a plain piece of tube, and loosened the valve nipples a quarter turn to let air and oil out as I turned the wheel.

8. Once all the bleeding was completed I tightened up the nipples and carefully removed the tubing and bottle of oil. The reservoir was now overfull and needed some oil removed.

9. Like a mini dipstick, the spigot moulded into the oil reservoir cap shows what the correct level of oil needs to be.

10. Rather than just putting the cap back in, spilling oil every where, I used a medicine dropper to remove the excess.

11. All back together and working. Notice the effect the new right angle connector has on the run of hoses. The boat is now kept indoors so future deterioration should be minimal.

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