Can ATF evaporate?

[Rivers & creeks]

Hydraulic steering issue - we have full hydraulic steering, with a simple wheel acting as pump in the wheelhouse. The boat sat unused for two years and I foolishly never checked the steering fluid level. Today after another 2 months non use and with her due to go back in, I checked the steering and there was no fluid in the steering pump. I checked the lines and can't find a leak, then I noticed that the nut on the wheel pump used for filling had a designed hole, about the width of a big sewing needle. Can ATF evaporate through that? I bought a bottle and put in about 200ml; assuming the level hadn't been topped up for about 4 years, is that feasible as a cause or do I have to look elsewhere for the problem? the wheel is the highest point in the system so I'm assuming the air bubbels will rise to that point? The wheel is now a bit 'juddery' and I'm guessing that's due to air in the system that has to come out???
Thanks for advice.

 

[RobinBirch]

Dunno if ATF evaporates or not. I suspect there will be small weep of fluid somewhere - check the ram. There does seem to be a tendency to lose a bit of fluid around this area. Having replaced one then found the new one has the similar weeping characteristics as the old!

I live with it, check the fluid levels periodically and carry a bottle of ATF on board.

 

[Hoolie]

I don't think so, at least not through a small hole. I think RobinBirch is right in thinking you have a leak somewhere. Though it might evaporate in open air from a minor leak.

 

[westernman]

Dunno if ATF evaporates or not. I suspect there will be small weep of fluid somewhere - check the ram. There does seem to be a tendency to lose a bit of fluid around this area. Having replaced one then found the new one has the similar weeping characteristics as the old!

I live with it, check the fluid levels periodically and carry a bottle of ATF on board.

+1

 

[Rivers & creeks]

Thanks for the replies. Do you think the long inactivity will have caused problems for the seals? And any idea what causes the juddering on the wheel - could it be air in the system?

 

[vyv_cox]

ATF is low viscosity oil with quite a loading of additives for boundary lubrication. It won't evaporate any more than engine oil will.

 

[Rivers & creeks]

Sounds like a leak then - which sounds like money

 

[PCUK]

Don't worry about a weep. Just top up as required. Juddering is caused by air which should self bleed with use. Hence the vented filler plug!

 

[sarabande]

If it is the same as mine, then you fill up, turn the wheel from full lock to full lock a couple of times, then top up again as necessary.

The juddering will stop when all the air is out of the pump (on the wheel spindle).

Bet you have a leak at the ram for the quadrant by the rudder stock though.

 

[Sandyman]

We have a Wagner A-W helmpump. Been out of production for over 30 years so spares are really hard to find. Seem to have a constant small leak/weep on the fluid.
Where it goes no body knows. Search as I may I have never been able to find it. Placed tissue paper at all the suspect places for an indication, but nothing.
Just live with it now. Lose approx 50 ml over a four month period.
Its not a problem because we have a header tank made from a clear plastic bottle and plastic pipe which leads to the front bleed screw on the pump via an adapter. The bottle is kept in a bracket above the height of the pump and is the highest point in the system. This keeps it topped up & allows it to self bleed. I have put graduation marks on the bottle such that I can monitor any losses.

When buying hydraulic fluid use ebay. I got 20Ltrs of tellus10 for 50 quid. In Ltr bottles its around £18 a Ltr from chandlers & the like's of Halfords.

If anyone ever comes across such a pump or parts I would be grateful to hear from you.
I carry spares for just about everything onboard but have non for the Helmpump. Thanks.