Adding fluid to Hynautic steering (48YF)

[silverpaul]

I assume I have Hynautic steering as there is a cylindrical reservoir with a sight glass and pressure gauge. My question is where to add fluid? The bicycle valve is threaded into a large (7/8?) nut but that is all there is on the top. I tried loosening the nut and the valve but both were extremely tight and I stopped before I broke something as I did not have the correct sockets available only adjustable wrenches. The fluid is about half full and the pressure was at 15 psi.

I searched this forum and read a lot about the choice of fluid and was surprised to see in my Hatteras owners manual they advise ATF type A not the hydraulic fluids (Mil spec or Teleflex) that I have used in previous boats.

Paul
FREEWAY
48YF Oxnard CA

[bobk]

Usual advice for these situations. Soak a day or two with PB Blaster and use a large socket or box wrench. Or an impact wrench. Sometimes tightening a bit allows it to be loostened. On my 48MY I use the mil spec fluid.

Bobk

[Canuck Dennis]

How do you tell what's in there to start with, I doubt you can mix mil spec with ATF A ??

[Bugsy]

I think the answer to your question is; "Yes. You're at the right spot. That nut comes off and that is where you fill the reservoir." I suggest that you follow the manual which is express.....do not use ATF --I think it says Detrol for emergency use only.
I think recommended psi is 25-30 but again...check manual.

[SKYCHENEY]

That large plug has a rubber seal on the bottom and can be in there very tight. Get long wrench and loosen it. It will break free. The proper fluid is Hynautic fluid or mil spec 5606.

If you have a leak, you need to find it. Don't just keep adding fluid. It will only get worse.

[silverpaul]

Thanks for all the info. I was concerned about using WD-40 or some other penetrating oil in case it got in the reservoir - just be careful I guess. The fluid in there appears reddish from the sight glass so I was assuming ATF. I would like to add clear Teleflex fluid that I have - anyone know if mixing is a problem?

Thanks,

Paul

[davidwigler]

The fluid is about half full and the pressure was at 15 psi.

Half full is fine. There should be a fill line below half full. What is the problem?

Don’t fill it. It needs air to pressurize the system.

[Pascal]

Air should not enter the system unless there is a leak as hydraulic steering is designed to be sealed. Many smaller boats (single helm) don’t have a reservoir and are simply filled by gravity at the helm pump. Works fine for years without air coming in.

[Dan Mapes]

We lost steering in the Bahamas while docking. All along the years we had the boat the gauge indicated 25psi. As it turned out the gauge froze and air got into the helm because there was no pressure. I will suggest an occasional test that cycles the air gauge.