Vetus hydraulic system

[pedro666]

hi, i have a boat with a vetus mtp30 helm pump that has built in check valves.

This is piped into a dual non return valve that also has a feed from an auto pilot pump , from the dual check valve it goes to the steering ram.
All the parts except helm pump are brand new and after installation were bled to remove all air.

When turning the helm pump it is very juddery .
When put to full lock the wheel will go solid then very slowly start to move like its releasing oil (there are no external leaks), when i go to steer opposite way there is a dely and then a jolt like the check valves are releasing.

Now, i think as the helm pump has got built in check valves that the added dual check valve is needing such a build up of pressure to release it.

When the dual check valve is taken out of the system the helm pump works nice and smooth.

However, i have completely removed the helm pump and with both pipes in a drum of oil with clear pipe it draws up the oil with no air bubbles but the outlet is full of them,on both directions, like its not drawing in air from the supply but from within the pump.
I read that the helm pump has an auto bleed system in it but would expect the air to be released into the tank,not the feed lines.

Any help would be great

 

[superheat6k]

Sounds like entrained air locks.

Try setting the auto helm to steer say to Port (Auto > -10 x 2) then spin the wheel to Stbd, then after a few minutes reverse the auto helm (Standby > Auto > +10 x 2) and spin direction. This might shift the air locks possibly causing your problems.

Also check along the lines that there are no inherent air locks / high spots and if so try to lift these to move the air bubbles along to the helm pumps.