Steering system trouble shooting

[furball]

I have a 2005 31TE.
I replaced the helm pump and steering cylinder shortly after purchase. Changed cylinder size to reduce the number of turns lock to lock. I installed the cylinder that most 31’s seem to have from the factory, mine was larger. I replaced the SeaStar helm pump with a rebuild from SeaStar. The helm pump was replaced because of a heavy pulsating when turning out of a port turn back to center. I noticed it during the sea trail and the surveyor suggested replacing the pump.
The pulsing still exists and I’m wondering if it’s possible the autopilot pump has something to do with this. I have noticed that while the autopilot is engaged, 80% of the time the steering wheel will not spin freely to port, won’t budge at all, it always spins freely to starboard just like my previous Raymarine system.
Are there valves within the autopilot pump, check valves or bi-pass valves which could be causing the pulsating I feel when turning back to center as well as it not spinning free? It only happens at cruise speed, not hull speed. Turning to port at speed is fine, it’s only the return to center but it’s very distinctive, you can’t miss it, the wheel shakes in my hand .
The AP pump seems to be the only part of the system I haven’t replaced but I don’t understand the how and why of what’s going on.
Hoping someone can explain or take a more educated guess than I can.
Thanks,
John

[nebulatech]

This is out of my league, but I know hydraulics can exhibit pulsing when there is air in the system. Is there any way to bleed the autopilot?

[furball]

The autopilot pump is in the same loop as the helm pump. The system was bled when the new cylinder and helm pump were installed in 2019. There are no other symptoms of air as I understand it and the pulsing/chatter only occurs in one direction while coming back to center from a port turn while on plane.
I’m out of my league here as well. It doesn’t seem like air in the system as I have heard it described but I don’t know.

[dkirsop]

Maybe it's a mechanical problem where the ram connects to the rudder tiller? Perhaps the clamp holding the swivel is loose and the mechanical advantage is lost in one direction? That this has occurred with the old system as well as the new points to something other than the hydraulics.

[Norseman]

The autopilot pump may do the pulsating stuff.
Otherwise, I doubt it

[nebulatech]

Maybe it's a mechanical problem where the ram connects to the rudder tiller? Perhaps the clamp holding the swivel is loose and the mechanical advantage is lost in one direction? That this has occurred with the old system as well as the new points to something other than the hydraulics.

Excellent point

[johngus]

Can you take the autopilot out of the system for testing? Sure you can disconnect the hoses at the pump,put in a couple of bypass hoses and see if it still does the issue

[nebulatech]

Rereadingtheoriginal post, the problem only happens at cruising speed, when there is more force exerted on the rudder. Following dkirsop's vein of thinking, I would investigate the mechanical side of things at the rudder.

[furball]

No obvious mechanical issues. All appears correct. Nothing is loose. I could get down there while on plane and put a hand on the rudder but there is no visible movement of rudder, cylinder or mount from above. Been down there while on plane before and can’t say i like it
I’m still suspect of the autopilot pump. It’s the last part from the old system. Have a question into Raymarine now.
Thanks,
John

[RobS]

Cap the lines and isolate the pump.