Query On Hydraulic Steering

shirehorse · 23 June 2008, 10:02

When driving my rib i find i am having to constantly change my hand position as the wheel appears to rotate during the course of normal steering, does this make sense to anyone if so is this normal or do i have a problem.

reinier · 23 June 2008, 11:31

Well, most of the hydraulic steering installations have this problem... Sometimes it helps to refill your system, but I won't try that, maybe you can contact your dealer and ask him?

jon_95 · 23 June 2008, 11:46

there may be air in the system, how old is the system? if a check valve in the unit doesnt close properly this could also be caused but it should not be this way...

BruceB · 23 June 2008, 12:29

Adjust your trim tab on the outboard. If it is out much the wheel will slowly rotate as you go along.
Adjust it so that at normal cruising speeds the wheel is stationary using the direction the wheel is rotating as a guide to adjustment.

martini · 23 June 2008, 21:19

It's perfectly normal for the steering to creep round. Unless its excessive I wouldnt worry about it.

Erin · 23 June 2008, 21:28

Very timely.

I have the very same problem and contacted the suppliers of my system (fitted 2 months ago). They reckon it can be caused by bad trim of the engine, or by debris or air in the oil. On my system they said that if I turn it to full lock it shouldn't be possible to continue to turn the wheel more than a quarter revolution every 15 secs. If it turns faster than this then there is a problem with the lock valve. I will re-bleed my lines to make sure there is not air in them as well.

Bigmuz7 · 23 June 2008, 22:54

With hydraulics (In general.. not just steering systems), it should be either on or off, or pressure dependant.

What you guys are describing, is a leaking valve or a faulty pump, which in this case is the steering wheel as the pump. Regardless of the load, the pressure should be holding,.. in your cases it isnt,.. and you want it investigating, your fault is in the ram on the outboard, leaking, and allowing oil to bypass from one side to the other, or your steering wheel pump, doing the same, you keep having to turn the wheel to replace the pressure lost by whatever component is leaking, and compensate for the load provided by the outboard.

This leak will not provide any external signs,.. it will be internal between components so you will see no visual indication from the outside. So assuming your hoses are dry and no oil is evident, and you have enough oil in the system, these are your prime suspects

shirehorse · 24 June 2008, 10:12

Thank you for a heap of very informative replys looks like i will have to remove the wheel and strip it down, not sure of its age but would put it near twenty.

BruceB · 24 June 2008, 12:11

I had this very problem moving from NFB cable steering to hydraulic. While NFB will not transmit loads back through to the wheel as it is a worm drive mech, hydraulics will in certain circumstances without there being any fault or leak within the system.
There is an overpressure valve to stop high loads building up enough pressure to burst things like hoses. If there is enough pressure caused by bad trim then this will let oil leak past it and cause the turny wheel effect.
Before stripping the whole thing down I would seriously try and adjust the trim tab, it is amazing just how much this can adjust out.

Mark Halliday · 24 June 2008, 12:54

Hi Shirehorse.

Don't start stripping your unit down. You will have springs and ball bearing all over the shop in seconds.

Strictly speaking the pump is not a pump and should be known as a helm unit. It is more like an automatic transmission torque converter, and consequently will leak like a sieve with any sort of back pressure.

If the steering ram is under any sort of pressure it will shove fluid back round the system and the engine will turn. That is why you keep turning (I bet it is to the right) to compensate.

Adjust the trim tab to get the boat tracking straight at cruising speed. It will take some time because it involves a bit of trail and error.
You will find the tab under the cavitation plate, just above and behind the prop.

Tip.
The tab is also an anode and so it will need replacing every so often. There should be a line on the tab. mark its position on the cavitation plate so you can put a new tab in the same position.

shirehorse · 24 June 2008, 16:03

Thanks Mark and Bruce i will do this should be easy as the bottom of the ventilation plate is marked in sections and the trip tab has a line on it. sounds like much more fun than getting covered in oil cheers Ian