Hydraulic Steering Maintenance

FindherKeepher · Jul 16, 2018

I have a 1999 Mainship 390 which we are still learning about. I need to service the upper station steering. I would like your help in knowing what type of hydraulic fluid, and the proper way to service the system.
Thanks in Advance

Lou_tribal · Jul 16, 2018

FindherKeepher said:
I have a 1999 Mainship 390 which we are still learning about. I need to service the upper station steering. I would like your help in knowing what type of hydraulic fluid, and the proper way to service the system.
Thanks in Advance

What do you mean by servicing it? Do you have any leak? Is there any issue? If not do not touch and keep it working the way it is.

L

FindherKeepher · Jul 16, 2018

Lou_tribal said:
What do you mean by servicing it? Do you have any leak? Is there any issue? If not do not touch and keep it working the way it is.

L

The wheel seems to be more stiff than normal, I do not see any leakage.

tiltrider1 · Jul 17, 2018

Is it a pressure system or a return line system?

crashley · Jul 17, 2018

Do lots of research find out exactly what brand and model all the components are Pump valves rams auto pilot etc and then get the exact service instructions for those before doing anything
Just loosening the wrong fitting in the wrong sequence can mean no steering at all

Keysdisease · Jul 17, 2018

I believe Mainship abandoned Hynautic before the 390 went into production, but I could be wrong. Most 390's have Sea Star by what was Teleflex, which is a simple and reliable system.
Picture below is a Hynautic Reservoir, if you've seen one of these somewhere aboard check the pressure guage.

If you have a Sea Star system (black helm) use only Sea Star fluid available at most marine stores. Others will say there are cheaper substitutes but I consider this a bad place to save a few dollars.

As Teleflex hydraulic is now Sea Star Solutions and Teleflex bought Hynautic, manuals for both systems can be found here:

SeaStar Solutions

This should get you started :socool:

FindherKeepher · Jul 17, 2018

Keysdisease said:
I believe Mainship abandoned Hynautic before the 390 went into production, but I could be wrong. Most 390's have Sea Star by what was Teleflex, which is a simple and reliable system.
Picture below is a Hynautic Reservoir, if you've seen one of these somewhere aboard check the pressure guage.

If you have a Sea Star system (black helm) use only Sea Star fluid available at most marine stores. Others will say there are cheaper substitutes but I consider this a bad place to save a few dollars.

As Teleflex hydraulic is now Sea Star Solutions and Teleflex bought Hynautic, manuals for both systems can be found here:

SeaStar Solutions

This should get you started

Thank you so much for the information. I believe I have a sea star but will confirm Thursday when I'm able to return to her. I'm sure I'll have further questions then.

what_barnacles · Jul 17, 2018

These guys can rebuild your unit if need be.

Boat Steering Solutions Home

Twilight time · Jul 18, 2018

I had Hynautics in my 86 SEnator had to rebuild both upper amnd lower helm pumps , the resivior, checked the ram and still would not hold pressure. Eventually had to re-plumb the entire system,with new high pressure tubing Very frustrating trying to track down the leak. It is holding pressure now and all seems well.

diver dave · Jul 18, 2018

FindherKeepher said:
The wheel seems to be more stiff than normal, I do not see any leakage.

"stiff" hydraulic systems can be caused by the rudder post bearings, stuffing, etc. I would not attack any helm rebuild unless the rudder is proven to be free OR, you have a second helm, and it is "not stiff".

Hydraulic Steering Maintenance

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