Steering Creep Whilst Standing

Nasher · 15 June 2009, 12:47

Is mine normal?
(The title and first sentence of this thread don’t start well do they?)

When I leave my RIB for a couple of weeks or so, sometimes, not always, the engine creeps round to Port very slowly by itself, just enough for it to be noticeable, but carries on going the longer its left.

The hydraulics are a miss-match of parts put together by myself consisting of a 28cc per rev helm pump, that I brought new a couple of years ago and can’t remember the maker of, plus an LS front mounted ram which I brought used but in very good condition @4 years ago now. I can’t remember if it happened with the old helm pump.

From memory it does only appear to happen when the weather is warmer, so I’m wondering if it has something to do with the viscosity of the fluid.

It all appears to work faultlessly otherwise, but if I need to start stripping it down to replace seals etc I’d like to do it before our annual boating week in Dartmouth which is only a few weeks time now.

Does anyone else experience this? Or has done in the past before a failure?

Thanks

Nasher.

Pete7 · 15 June 2009, 13:02

Old Spice did this too whilst you were under way. Noticeable on a long trip you would slowly be turning the wheel more one way, but it was such a small amount, never really worried me.

Pete

PeterM · 15 June 2009, 14:41

Mine does this - I find the engine position compared to wheel position moves slightly over time.

Guess it means something is less than perfect by way of seals etc ? I try not to think about it. I'll proabably find fluid & 'bits' all over the place when I go out to the boat later today now !

Poly · 15 June 2009, 15:56

On the positive side - if things are moving (even slowly) - presumably they aren't seizing!

codprawn · 15 June 2009, 15:59

Most hydraulics leak to a certain extent - that's why industrial equipment has big hydraulic tanks - they only get worried when the leaks get silly and they are wasting too much oil.

jyasaki · 15 June 2009, 16:18

There's usually a couple of check valves at the helm outputs; they often get a bit of corrosion or something blocks them open a bit; they can be cleaned up if the problem gets too bad, but if it's over a couple of weeks, I wouldn't even think about it (actually, I probably wouldn't notice.)

Could also be due to air in the lines.

jky

PeterM · 15 June 2009, 16:25

Its on my list of things to worry about end of the summer. I dont want to tempt fate by trying to fix it now & then not being able to use the boat for weeks waiting for a part.

I say fix it , I mean - pay someone else to sort it when the boats lifted serviced etc in November !

I did see someone resort to the old ' 2 ropes tied to the engine runing to the console' method of steering at the weekend , but not sure I will get away with that on a 200! Pull left hand to go left - pull right hand to go right . Not sure what was pushing the throttle - but I have seen a very good looking girl in the boat before ..........

Nasher · 15 June 2009, 16:57

Thanks guys, glad it's not just me.

I presumed it was fluid leaking past a seal somewhere in the system.

Its only leaking from one side of the system to the other, as there is no overall fluid loss. It is really a small movment over a couple of weeks or so.

It would make sense that I notice it more in hot weather as the fluid is warmer, less viscous, and probably leaks past quicker.

Nasher

Hightower · 15 June 2009, 18:38

Did you happen to notice if the steering ram was extending or retracting?

My guess would be that the sun is warming the Hyd oil in the cylinder and expanding the fluid which in turn pushes the engine over. To be fair I doubt that a check valve would compleatly seal at such a low pressure and would be made worse with wear. Thus the creep!

Bigmuz7 · 15 June 2009, 18:40

It could be a combination of things , could be that your pump is making the oil 'foam' during use, this can be caused by the incorrect grade or a contamination of your oil, and also air being present in the system. The air will be getting beaten into the oil like 'whisking an egg', and it will percolate to one particular place where over time the air bubbles get released back out from the oil, allowing compression variation in the circuit, as air is highly compressible, where as the oil is not. It would further be compounded by ambient temperature, where if it rose, it would make the air expand, which in a sealed circuit, would cause a shift of the only movable actuator in the circuit whilst at rest, which is the steering ram.

If your engine does this whilst tilted up, gravity might then take over if the seals in the ram are poor, on the other hand, if it does it whilst trimmed down, and keeps going .. that is a conundrum

Nasher · 15 June 2009, 23:00

Some interesting thoughts thanks.

being a front mounted ram it has a connection at either end, so is not exactly extending or retracting, but both.

Whilst being stored I drop the engine back down, so its happening then, not when lifted up.

Nasher.

Kernow Buoy · 15 June 2009, 23:08

Apparently in the southern hemisphere engines will rotate to Starboard.

Hightower · 15 June 2009, 23:36

Kind of like the direction water dissapears down the plug hole

kitten · 16 June 2009, 06:37

In the American embassy in Australia the have a device to make the water flow the "right way" down the toilet. ( It's true I saw it on the simpsons.) A bit like Codders big tanks on industrial hydraulic units which are to combat leaks, and nothing at all to do with cooling and having enough oil in the system to fill large unbalenced rams.
hydraulic steering will creep due to the way it handles impact loads (as I understand it.),
As long as it is full of oil and you can't move the ram too much by pushing the engine side to side don't worry about it. Get a symetrical steering wheel and you will hardly notice.

codprawn · 16 June 2009, 22:34

I didn't say it was the only reason................

kitten · 17 June 2009, 10:33

Quote:

Originally Posted by codprawn

Most hydraulics leak to a certain extent - that's why industrial equipment has big hydraulic tanks - they only get worried when the leaks get silly and they are wasting too much oil.

doggypaddle · 17 June 2009, 12:01

hydraulic steering always creeps. one of the reasons its not suitable(or legal) for road vehicles. Don't worry about it until it gets like our old JCB, had to rotate the steering wheel wheel a 2 rpm to keep the wheels straight

Bigmuz7 · 17 June 2009, 18:59

Quote:

Originally Posted by doggypaddle

hydraulic steering always creeps. one of the reasons its not suitable(or legal) for road vehicles.

So whats power assisted steering then ?

.. as fitted to cars, trucks , buses etc.... When it comes to JCB's you cant beat driving an old 2WD version with really worn front pinions through the Clyde tunnel dual carriageway with a 9'6" lane width restriction .. just to go straight .. you had to give the steering wheel a 2/3rds turn one way, then the other, to correct the opposite wander. Any miscalculation on your part would have your front bucket take the side off somones motor like a tin opener

Nasher · 17 June 2009, 20:14

Pure hydraulic steering as used on Competition Rock Crawling 4x4s etc is not legal for road use.

I might have the wrong idear, but it's something to do with there being no direct mechanical connection.

As I understand it, Power (assisted) steering is just that, in that the fluid is used to assist the direct mechanical connection.

If that makes sense.

Nasher.

doggypaddle · 17 June 2009, 20:30

Quote:

Originally Posted by Nasher

Pure hydraulic steering as used on Competition Rock Crawling 4x4s etc is not legal for road use.

I might have the wrong idear, but it's something to do with there being no direct mechanical connection.

As I understand it, Power (assisted) steering is just that, in that the fluid is used to assist the direct mechanical connection.

If that makes sense.

Nasher.

thats it exactly. if PAS fails then the steering gets a bit heavy.
if full power steering fails it can whizz onto full lock and the steering wheel can rotate with enough force to break fingers! the metering unit in the orbitrol steering valve can act as a motor