Problem bleeding hydraulic steering

[neiloakley]

Setup: Twin rudder, single ram, twin seastar helms (in saloon and flybridge)

After my autopilot hydraulic pump motor seized, I took it off and fixed it before replacing it. This mean air got into the system so i proceeded to top up the fluid and bleed it.

When i tried to remove the filler cap on the upper helm, the fitting had seized so it had to be replaced. I used seastar part number HA5431

I then followed the instructions to bleed the lower helm first. Starting by filling the helm with oil, then connecting a filler tube to the helm so it had a constant supply of oil, and with a friend began to turn the wheel left/right opening and closing the bleed valves on the ram in order.

The instructions then go onto say repeat at the upper helm.

My problem is no matter how many litres of oil i circulate, there still seems to be air in the system. I can now turn the lower helm 2 or 3 times before there is a 'donk' and the steering starts to move. Also on full lock there isn't a hard stop like there used to be - I presume because there is air in the system that can be compressed.

Any ideas why i'm having trouble bleeding? There was no issue before I took the autopilot pump off, and i'm not leaking fluid anywhere.

 

[superheat6k]

Assuming your Autohelm pump and system is working, select auto then say 30 degrees to port, then spin the lower wheel to stbd, for several turns. Check the level at the upper pump and top up as necessary.

Then same again but auto to stbd, spin to port.

Then repeat the whole process at the upper pump, but do not let the fluid level drop more than 1" below the filler level.

You might need to repeat the whole process several times to make sure all the bubbles rise to the upper pump and vent away.

As you might cause some tiny bubbles repeat a few days later when these have risen.


This should purge your lines, but check there are no sags along the run causing airlocks, if so lift the sag to let the air rise to the helm pumps.

 

[PCUK]

You are filling from the upper helm while bleeding the lower I presume?

 

[SEARANGER ANCASTER]

https://www.youtube.com/watch?v=smKMklBQbfo

 

[neiloakley]

thank you everyone for the replies.

Assuming your Autohelm pump and system is working, select auto then say 30 degrees to port, then spin the lower wheel to stbd, for several turns. Check the level at the upper pump and top up as necessary.

So turn lower wheel, but top up at upper helm? How would any fluid move in the upper helm if it's not turning, I thought the valves would have been closed.

You are filling from the upper helm while bleeding the lower I presume?

No, instructions say to fill from the lower helm first whilst bleeding at the ram, then once that is complete only then should I start to fill at the upper helm and bleed there?

 

[PCUK]

Right, I thought you were trying to bleed with the system full! We had a recent bleeding problem and eventually found that the by-pass valve in the (brand new) A/P pump was not fully closed and this was allowing air to pass back and forth between port and starboard pipe-work. This after putting about a gallon of oil through the system!

 

[neiloakley]

Right, I thought you were trying to bleed with the system full!

Should I? I can probably make up another filler rig and connect it to the upper helm. That way both helms have a supply of oil and I can begin by bleeding the autopilot pump, then the lower helm, then the upper helm.

 

[longjohnsilver]

We had a similar problem a few years back. I filled from the upper helm station but every now and then, especially when the temperature increased, we would get a spurt of hydraulic fluid out of the vent hole in the filler. I never got to the bottom of it, but what I did was connect a long plastic tube to the filler and part filled that with hydraulic fluid and hung it up vertically. Sometimes it would virtually fill and other times it would all virtually drain back into the system. I kept it connected for a few months until it eventually settled down, and only then did I screw in the filler.

That was a few years ago now, and it's all been fine since.

 

[neiloakley]

So before i removed the pump motor, everything was fine. No leaks, no spongyness, no fluid seeping from either helm fill point.

The vent cap I removed at the top helm had a ball bearing on a spring in it, so it would let air out but not suck any in.

The new valve i bought (by part number from seastart) does not have a BB in it so it looks like air can flow in and out freely. Do i have the wrong vent cap on the top helm?

 

[PCUK]

On my system I bought an old master cylinder reservoir and connected it to the top helm and situated it above the helm inside the instrument panel. This meant there was always excess oil available and room for expansion.

 

[superheat6k]

This might help ...

https://www.dropbox.com/s/nc4rve9mlig6wgv/Teleflex Seastar instruction manual detailed.pdf?dl=0

 

[rogerthebodger]

We had a similar problem a few years back. I filled from the upper helm station but every now and then, especially when the temperature increased, we would get a spurt of hydraulic fluid out of the vent hole in the filler. I never got to the bottom of it, but what I did was connect a long plastic tube to the filler and part filled that with hydraulic fluid and hung it up vertically. Sometimes it would virtually fill and other times it would all virtually drain back into the system. I kept it connected for a few months until it eventually settled down, and only then did I screw in the filler.

That was a few years ago now, and it's all been fine since.

I have a similar problem and I put it down to having an air lock somewhere in the piping and as the temperature changes the air in the air lock expands and contracts thus pushing the oil up the filler tube. Over time the air can work its way out thus fixing the problem over time.

 

[neiloakley]

This might help ...

https://www.dropbox.com/s/nc4rve9mlig6wgv/Teleflex Seastar instruction manual detailed.pdf?dl=0

Thanks, although I already have the instructions and followed them to the letter.

I'm going to try some of the suggestions on here. Will connect a source of oil to both helms while I bleed the lower one - that way I can be sure no air is being sucked into the vented filler cap on the top helm. I will also try running the autopilot pump to bleed that.

I shall report back next week.