Mixing hydraulic steering fluid

[JulianGullsway]

Hi, I'am hoping some one can help, we have hydraulic steering on our yacht, when it was installed it was filled with a Vetus steering fluid however we are currently in the med and are having trouble finding it, we have just installed a new hydraulic auto helm and it needs a top up, can you mix differing hydraulic steering fluid...

Thanks in advance Julian

[leftbrainstuff]

As a rule dont mix hydraulic fluids. But in your case you have no choice.

The easiest option is to drain what you have and fill with one of the common automatic transmission fluids you would put in your car.

The biggest issue will be seal degradation. This is less of an issue with newer systems.

If you can determine what type of seal material is used in your system then its possible to provide specific advice.

You can also use engine oil if needed. The rule of thumb is don't use anything fancy. Just a straight plain 30 weight oil if possible. Unpowered hydraulics are fine with engine oil.

If you have the time and spare seals then you can test them in some of the new fluid to see if they swell or their durometer changes (they become more flexible or get harder). Sometimes you can sacrifice the filler seal as the test case. Note that a complete test will test both the new fluid and a mix of the two.

Measure them before, during and after with vernier calipers across the major dimensions. If there is a seal / oil incompatibility you'll notice it in a few days or even up to a week.

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[hellosailor]

Silly question but have you tried the Vetus contact list?
FIND VETUS NEAR YOU


And in the worst case, surely someone in whatever corner of the Med you are in, can send a couple of liters down to you?


I'd be afraid to use automotive transmission fluid. Used car dealers are infamous for putting that in brake systems, where the ATF swells the rubber seals and temporarily stops leaks--until the seals degrade and fail totally because of the reaction to the ATF. "ATF" can be a number of highly incompatible fluids.


I suspect the best answer is to either have some shipped out to you, or to drain and perhaps purge the system and then refill with something of the correct spec, even if it is another brand.

[JulianGullsway]

Thanks for your reply, the whole steering system is less than 5 years old the new hydralic pump is ray marine the fluid used on installation is Vetus HF15 and the fluid I can get is ATF Dexron 2 if that's any help, thanks so much for your speedy response

Julian

[cagney]

Have a look at this page Vetus-Shop.Com : Vetus Hydraulic Steering Oil LHM 1 litre (Vetus VHS1)

Vetus Hydraulic Steering Oil HF15 is a low viscosity oil for hydraulic steering systems with optimum results at all temperatures.

This oil has a very low coagulation point and a very high viscosity index. May be mixed with other hydraulic mineral oils.

Specification
Viscosity: 22 cSt at 20° C.

My highlighting.

So it's pretty much a standard hydraulic oil, but quite thin. Just search the net for "hydraulic oil iso vg 22" or ask around locally. No need to drain anything as long as you get a standard mineral based oil. No green Bio oil or ATF!

Warning do not use "ATF Dexron 2". It does not mix well with mineral oil.

Thomas

[Dave852]

+1 on the ISO 22, shell telus makes one you should be able to find most places. That's what I use in my Lecombe & Schmitt steering.


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[TheThunderbird]

My rigger told me to use ISO32, and not any higher number. Higher viscosity can dsmage the system

[GalleyHo]

All you have to do is have your steering fail once to find out how important it is to have the right hydraulic fluid. We bought a new boat with hydraulic steering. A few months later, I checked the reservoir and it was low. There was a Teleflex steering fluid container with fluid in it that came with the boat, and so I topped up the reservoir.

Over the next few weeks, the steering wheel became a bit harder to turn. I thought it might be growth around the rudder, as I hadn't cleaned the bottom for a while, and where we were, it built up quickly. Leaving an anchorage a few days later, my wife suddenly said, "I can't move the wheel!" I went back from the bow to the wheel, and sure enough it was very hard to turn the wheel. I gave it a yank and suddenly the wheel had no resistance whatsoever. Whoops --- had we lost steering? Yes we had! A hydraulic fitting in the steering lines had given way.

We survived, although getting reanchored safely with no steering was a bit dicey.

The problem was with the hydraulic cylinder that drove the rudders (we have a cat - 2 rudders). It had seized up. After being removed, it was impossible to move the rod. My hydraulics guy took it apart and said the nylon bushing that held the cylinder o-ring had swelled up and completely jammed the cylinder. It took him 45 minutes just to get the piston out.

We later looked at the "Teleflex" fluid and determined that it definitely was not the real thing. Wrong color; wrong smell. My mechanic thought that it was brake fluid. Since the prior owner spent most of his time in the Caribbean, I think someone may have gaven him auto or aircraft brake fluid to top up his hydraulics because they didn't have the right stuff. Brake fluid has to survive very high temperature and has all sorts of nasty additives to do so. If you have ever messed with brake fluid, you know that it will eat the paint right off your car if you spill it. It evidently also eats boat hydraulics.

Let me tell you that there is nothing like suddenly loosing all steering. I used to think that Teleflex hydraulic fluid was expensive, but no more. Go with the real stuff---whatever your manufacturer recommends--- don't cut corners. There's no telling what plastic parts in your system may not like some ingredient in non-standard fluid.

[seven south]

I definitely wouldnt put brake fluid in your system.

At best you will jeopardize your seals......and lines.....

At worst you will seize your steering when you need it most.

[belizesailor]

Interesting that this thread should pop up just as I'm considering a related subject:

My system has a Capilano 1275V helm pump and SeaStar BA125-7ATM rams. The Capilano manual specifies ATF and the SeaStar MIL 5606 or other compatible standards. I've always run a mineral oil based fluid in the system (like MIL 5606, that's what it was originally filled with), but as a cruiser have often had to go with what I could get...which has of course resulted in mixing fluids of differing brands/specs. Fortunately never any problems other than the usual seal replacements for 14 years now so obviously this approach works.

What technically should I run in this system?

I've got the same question into Teleflex and will post their response. Its time to rebuild my old helm pump and would like to start off right.

[belizesailor]

Originally Posted by belizesailor

Interesting that this thread should pop up just as I'm considering a related subject:

My system has a Capilano 1275V helm pump and SeaStar BA125-7ATM rams. The Capilano manual specifies ATF and the SeaStar MIL 5606 or other compatible standards. I've always run a mineral oil based fluid in the system (like MIL 5606, that's what it was originally filled with), but as a cruiser have often had to go with what I could get...which has of course resulted in mixing fluids of differing brands/specs. Fortunately never any problems other than the usual seal replacements for 14 years now so obviously this approach works.

What technically should I run in this system?

I've got the same question into Teleflex and will post their response. Its time to rebuild my old helm pump and would like to start off right.

Teleflex recommended Dexron ATF. So, after 14 years using mineral oil based fluids, I'll be switching to ATF after the rebuild. Good to know at least that mineral oild based fluids will work too. ;-)

[motaman9]

It has been a while since we added or changed the fluid in our autopilot fluid pump and our system is an older one but if I recall correctly the Teleflex/Seastar fluid we use is essentially just vegetable oil. I'm sure it's purified or has some preservative or additives to prevent growth or degradation but they sell it at West Marine by the quart. It seems to work well and if it leaks or gets spilled into the bilge and ends up being pumped overboard you don't have to worry about it. I have read that the Capilano systems use Dexron but I think most don't work with brake fluid or anything flammable.



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