Hynautic steering goes to one side only

[Atraxia]

Hello forum friends,
After replacing our hydraulic steering cylinder seals, reinstalled, did all the necessary bleeding and turning of the wheels and yet both stations and the autopilot steer well to Std but not to port.
The wheels turn and there is some resistance (feel of pushing oil through the system) but the cylinder barely moves or just stays put.
Any ideas or insights will be most appreciated!!
Thanks in advance!

[HankOnthewater]

There is either:
- a stuck valve (that does not open in one direction)
- a ram that does not have ends stick out the ram on both sides
- or other difference in cylinder volume (comparing both sides of the stroke)
- something else

[Atraxia]

Thank you Hank.
Unfortunately it falls in the ‘Something else’ catagory.
Everything was fine until I took out the cylinder to replace a leaking seal on one side of the ram. I installed it doing all the usual operations to take out air bubbles. The strange thing is that both steering stations and the autopilot now act the same.
No problem to std, won’t steer to port. Slowly moves with many turns of the wheels but doesn’t stop at end of stroke.

[Chotu]

What about contamination? The smallest thing that gets into the system can cause the valves to stop working.



If the auto pilot and the helm are doing the same thing, the problem is in the ram.


If everything was working fine before you did something, suspect what you did. Always.

[Chotu]

And as much as it is a terrible thing, you’re going to have to open that ram back up and double check the seal. Because it also sounds like as you turn to port, some fluid is making it past the seal but it is not moving the ram. Either that, or you are loading up a relief valve with pressure and it’s letting it by.

As I was looking for a diagram of the internals of the Seastar system, I did notice this. And that makes me even more suspicious of your fix.

There are almost no parts inside the ram. It can really only be those seals that you replaced or valves somewhere else.

https://www.seastarsolutions.com/wp-...05/343335E.pdf

[HankOnthewater]

Not knowing your ram, but could the seals being put the wrong away around, or one set of them?

[pcmm]

Did you close the bypass valves on the relief block for both sides? To me, it sounds like one of them is still open.

[pcmm]

Originally Posted by Chotu

And as much as it is a terrible thing, you’re going to have to open that ram back up and double check the seal. Because it also sounds like as you turn to port, some fluid is making it past the seal but it is not moving the ram. Either that, or you are loading up a relief valve with pressure and it’s letting it by.

As I was looking for a diagram of the internals of the Seastar system, I did notice this. And that makes me even more suspicious of your fix.

There are almost no parts inside the ram. It can really only be those seals that you replaced or valves somewhere else.

https://www.seastarsolutions.com/wp-...05/343335E.pdf

If fluid was making it past the seal, wouldn't the cylinder be leaking profusely when trying to turn it that way? That's been my experience when I've blown seals in my Hynautic cylinder...

[Chotu]

Originally Posted by pcmm

If fluid was making it past the seal, wouldn't the cylinder be leaking profusely when trying to turn it that way? That's been my experience when I've blown seals in my Hynautic cylinder...

I’m not sure. But I don’t think so. The other seals should keep it in the system. The seals that are at the ends would keep the fluid in. And the big main seals on the piston could have a leak. That’s what I was thinking.

There really isn’t much else involved. They’re actually isn’t anything else involved. They are just empty tubes.

[pcmm]

Originally Posted by Chotu

I’m not sure. But I don’t think so. The other seals should keep it in the system. The seals that are at the ends would keep the fluid in. And the big main seals on the piston could have a leak. That’s what I was thinking.

There really isn’t much else involved. They’re actually isn’t anything else involved. They are just empty tubes.

A hynautic steering system has 4 basic components 1. Cylinder 2. Relief block 3. Reservoir 4.helm pump (plus all the tubing).

Having no pressure in the reservoir will stop all steering (usually there is 10-15psi). The last step in purging/bleeding the system is to open the valves in the relief block and turn the helm a number of times in each direction. When doing this step the rudder wont turn but you will be passing fluid through the lines to the relief block and back to the reservoir. Gets the last of the air out. If you leave one of the valves open a bit you can get the behaviour that the OP is describing. I've spent a long time sorting my system out. I've rebuilt everything, replaced lines. Its not a complex system but there are a lot of little gotchas in there!

[Chotu]

Originally Posted by pcmm

A hynautic steering system has 4 basic components 1. Cylinder 2. Relief block 3. Reservoir 4.helm pump (plus all the tubing).

Having no pressure in the reservoir will stop all steering (usually there is 10015psi). The last step in purging/bleeding the system is to open the valves in the relief block and turn the helm a number of times in each direction. When doing this step the rudder wont turn but you will be passing fluid through the lines to the relief block and back to the reservoir. Gets the last of the air out. If you leave one of the valves open a bit you can get the behaviour that the OP is describing. I've spent a long time sorting my system out. I've rebuilt everything, replaced lines. Its not a complex system but there are a lot of little gotchas in there!

What is the component you are describing as a relief block?

I just installed one of these systems myself.

The cylinders have the bleeders on them. Then they are just connected to the plumbing. I don’t have anything called a relief block in my system.

The closest thing I have to what you are describing is the liquid tie bar. Because I have a pair of cylinders.

To bleed my cylinders, you catch the steering fluid as it comes out of the cylinder bleed valve

So, we are probably, as most of the time when people aren’t talking the same language on the cruisers forum, picturing two different systems.

[pcmm]

Originally Posted by Chotu

What is the component you are describing as a relief block?

I just installed one of these systems myself.

The cylinders have the bleeders on them. Then they are just connected to the plumbing. I don’t have anything called a relief block in my system.

The closest thing I have to what you are describing is the liquid tie bar. Because I have a pair of cylinders.

So, we are probably, as most of the time when people aren’t talking the same language on the cruisers forum, picturing two different systems.

One of these:



The Hynautic system looks like this:



Its an older style of hydraulic steering. Technically called a 3 line system. There always has to be a bit of pressure in the system for it to work (which i think is a big drawback)

Seastar/Teleflex/Hynautic fully discontinued support for these systems back in 2021. So we are all on our own for parts/support

[rslifkin]

Originally Posted by Chotu

What is the component you are describing as a relief block?

I just installed one of these systems myself.

The cylinders have the bleeders on them. Then they are just connected to the plumbing. I don’t have anything called a relief block in my system.

The closest thing I have to what you are describing is the liquid tie bar. Because I have a pair of cylinders.

So, we are probably, as most of the time when people aren’t talking the same language on the cruisers forum, picturing two different systems.

I don't think you've got the 3 line, pressurized reservoir Hynautic system. I think your system is SeaStar or one of the other hydraulic systems. So you probably don't have the separate relief valve block being mentioned.

On the Hynautic system, the reservoir is pressurized so it doesn't need to be above the highest helm pump. There are 3 lines to each helm or autopilot pump. Port, Starboard, and the Reservoir line. The Port and Starboard lines tee together from all pumps and go to the steering cylinder. The Reservoir line goes to the pressurized reservoir for make-up fluid.

The relief valve block connects to the Port and Starboard lines at the cylinder and then has an output back to the reservoir. So if you turn hard against the stops and then force the wheel to keep turning, once you hit the pressure limit (ether 550 or 950 psi depending on the install) it vents pressure back to the reservoir to limit force at the cylinder and rudder (and prevent exploding hydraulic components). For bleeding, you can manually open the relief valves and turn the helm a bunch of times. This basically leads to pulling make-up fluid from the reservoir, pumping it down to the relief block and then returning it to the reservoir (which pushes all of the air in the lines to the reservoir).

[rslifkin]

Originally Posted by pcmm

Seastar/Teleflex/Hynautic fully discontinued support for these systems back in 2021. So we are all on our own for parts/support

Let's blame the proper villain here. Dometic bought Seastar and then decided to re-brand them and then kill off all of the Hynautic stuff (didn't happen right after the purchase). They pretty much scrubbed it from the website too. I'm no fan of Dometic, between a few poor quality experiences and stuff like this.



Fortunately, rebuild parts for a lot of the Hynautic stuff are still out there for now. Good thing, as my helm pump decided to blow the shaft seal and puke a quart of fluid onto the deck a couple days ago while the boat was just sitting on land.

[Chotu]

Well, that’s the problem. Like it always is on the forum. We were picturing different systems.

I was picturing what they sell now. Dometic/SeaStar/Hynautic. It’s all one thing now and it doesn’t include that component anymore.

My system is brand new. I was just picturing what they sell now. These days they call that a return line. That middle line. I do actually have a return line. But it’s from my auto helm pump. Goes straight from the autohelm pump back to the helm pump.

Your theory sounds perfectly reasonable given that there is that extra component in these systems. He should certainly start with that.