Big difference between upper and lower helm steering. Any ideads?

[Looking Glass]

When I turn the wheel at the lower helm one full rotation, the rudder turns 10 degrees. When I do the same thing at the upper helm it moves the rudder only 5 degrees. As a result, I am moving the wheel twice as much at the upper helm while under way.

The air pressure is fine and the fluid levels are fine. Once every couple months, I need to add a little air, but that is the only thing I noticed.

Any ideas on why this might be?

 

[kelpy]

Helm pumps are different.

 

[Fanfare]

Have you tried purging the system? Could be a little air in the top pump.

I thought we had purging instructions under "Frequently Asked Service Questions" but this seems to have disappeared. If you go to the "Search Forums" search section, top right of this page, and input "purge steering" you will get a bunch of suggestions. Unfortunately it will take 100 wheel revolutions in each direction, on each wheel and the autopilot to get the job done.

 

[sgharford]

Funny you mention this, I have same thing on my lower and upper helm. Takes 4 full turns starboard to port on lower, 4.5 turns on upper. ASSUMED they were the same helm pumps attached to each wheel and never could figure out the physics of it given fluid not compressible as I know I do not have air in the lines. The explanation of different pumps makes sense, never looked at them that closely.

 

[Looking Glass]

Thanks for the tips everyone. I never tried turning the wheel 100 times in each direction, so I will give that a shot. If it is working does that mean I should see a pressure drop on the gauge?

 

[kelpy]

If there is air in the system, the oil level will drop in the reservoir during bleeding but the system pressure pressure will remain the same.

 

[racclarkson@gmail.com]

If there is air in the system, the oil level will drop in the reservoir during bleeding but the system pressure pressure will remain the same.

Almost. Fluid pressure is constant, but the air is there to displace the fluid. If the fluid level drops, meaning its displacing air in the lines, the air pressure will also fall. Get air up to 50 psi during the bleed process to help the bubbles along (also from manual). If you get it to 50 psi and you see it slowly falling on its own it means the system is trying to bleed itself. Get it to a constant 50. You will also need to open up the bypass block before turning the wheel. When done, drop the air back to 20-30 psi.

Also manual states psi can vary around 5 psi due to temp fluctuations. Other than seasonal changes, my psi has remained the same since I repaired a ruptured line in July of '16.

 

[kelpy]

Assuming that the system is well maintained and leak free , it is a sealed system. It shouldn't make any difference if the air is trapped in a line, in a helm pump, or in the reservoir itself. The total volume system volume of oil and air will never change so the gauge pressure will never change unless the temperature changes..

 

[racclarkson@gmail.com]

Assuming that the system is well maintained and leak free , it is a sealed system. It shouldn't make any difference if the air is trapped in a line, in a helm pump, or in the reservoir itself. The total volume system volume of oil and air will never change so the gauge pressure will never change unless the temperature changes..

Right, but we're talking about a system that leaks.

 

[Pascal]

Upper and lower helm pumps can be different. Mines are. Upper helm takes 6 turns lock to lock compared to 5 for the lower helm

When purging air, you need to turn the wheel slowly. For some reason it helps... recommended by Southern Charm the rebuilder in Tampa

One odd thing on my system since rebuild, it take 30 to 35 PSI for the upper helm to work. Before that it took as low as 15psi. Other hynautic systems I ve used also worked on lower air pressure.

 

[kelpy]

You are correct. I missed the part about having to add the occasional makeup air.
In this case, the system needs to be repaired first before bothering with the difference in turns between the helms. Or, just keep adding air and/or oil.