hydraulic steering/auto pilot issue

[dogdoc]

Left this am for fishing trip and did not get very far before problem. At low speed in canal and channel all seemed good. Got to the intercoastal channel and on a plane steering started having issues (auto pilot not engaged) . When turning wheel seemed to skip and then catch. After a few minutes bam a large gush of hydraulic fluid came from backside of helm. Not sure which fitting but i think it was the low pressure one. At that point nothing worked well, auto or manual steer. Filled the cylinder (it was low) and turned the wheel side to side. Filled again, and turned side to side. At this point the autopilot was not controlling the boat well, and there was a bubble in the low pressure line. Turned off the pilot, then back on and cycled the hardover several times this cleared the bubble. Ran the boat about an hour with now issues, had to add a little fluid again but not much. Ran again and no problems. The only thing I can think of is that after last use several weeks ago I topped off the helm fluid and may have over filled somewhat.
Any ideas would be appreciated.

 

[seasick]

Has the weather been really hot lately?
When you say there was a gush of fluid from backside of helm, do you mean from the front of the dash around the steering wheel boot or actually from the backside of the pump (behind the dash)?

If the steering gets forced hard to one end or the other, eventually the pressure relief valves will open up but they should drain into the system not out the back. You may have popped a fitting, gasket or hose.
I think you may have separate issues. The skip and catch can mean that there is air in the system or one of the pressure valves is sticking.
Regardless, the gushing oil is something that needs to be looked at. The problem will most likely occur again.
If you over filled last time, the heat will cause pressure to build up. In that case the fill cap should have vented the extra fluid and that will often run down the dash. Your symptoms sound more serious

 

[SkunkBoat]

Fluid gushed out of where exactly? if it was a hose or fitting you need to fix that.

The helm fill screw cap can vent if overpressured.
you can overfill a helm/seastar system. it is supposed to have 1/4" below threads.

Seastar filler plugs

 

[dogdoc]

Follow up
A few weeks ago I topped off all fluids including helm hydraulic. I most definitely overfilled based on sea star recs (currently at rec fill level)
It has been very hot here the past few weeks
The boat has sat on the lift since I added fluid
Steering was normal at low speed in canal/ channel on way out
Within minutes of getting on plane on ICW it was clear something was not right, best I can describe is wheel seemed to skip then engage, but did respond
At that point we saw fluid on the deck under the helm
All leaking occurred from behind the helm bulk head, on the back side of the Sea Star helm
The leak was from a fitting, I cannot be sure if it was a steering line or the low pressure return as they are in line over each other and the top one ( return) could have been leaking on the lower ( steering) I think it was return line, but fluid was falling in my eyes and things were not that clear
The leak was a one off thing it never happened again
All fittings seem tight
We added fluid, did a bunch of turns and auto pilot maneuvers and problem resolved and has not reoccurred
Later the wife and I took a boat picnic to the sandbar at the inlet and had no problems at all

Could overfilling and high temp caused increase pressure which increased more with high speed steering causing pressure to increase in return line and thus caused fitting to act as "pop off" and relieve pressure

 

[seasick]

The fluid will definitely expand in warm temps. If the helm was covered while not being used, the temps can get pretty high.
I don't think that the fill cap on the steering assemble has a pressure release. If you have a single station, the cap at the steering box should be vented. There are vented and unvented caps. There is a way to tell one from the other but I can't remember right now.
That said, there should not be any case where a hose or fitting spit fluid but then that went away. I feel pretty certain that a problem will occur again.

Do you have power steering? If not there isn't a low pressure return line. Each line will be pressurized when the steering is turned. Which line get pressurized depends on which way the wheel is rotated..
The symptom you described is what you can get when the fluid is low and/or there is air in the system.

 

[dogdoc]

single station vented cap on mine, no leaking there
no power steering, but auto pilot
fluid has to have come from low pressure return fitting on helm

 

[seasick]

I see that there is a line called the compensation line that runs from the AP pump to the control. I guess that is low pressure but I really don't have a lot of hands on with APs

 

[SkunkBoat]

I just dont see how a fitting can leak and then not leak.
You have a Marlin so you must have 5/16 1000 psi hose on main hoses.

what kind of hose and fitting is on the compensation hose?
sometimes they use 3/8 nylon hose and compression fittings. They are prone to pop loose.

 

[dogdoc]

3/8 nylon hose, standard (but stainless) hardware store compression fitting. Steering hose are Sea Star spec, hose fittings are the parker field replaceable style fittings on the helm side are original and were not removed when installing the pilot. I really do not think it was the steering hose fitting that leaked. Is there someway the compensation/ low pressure return could have been transiently pressurized to point of leaking?

 

[SkunkBoat]

3/8 nylon hose, standard (but stainless) hardware store compression fitting. Steering hose are Sea Star spec, hose fittings are the parker field replaceable style fittings on the helm side are original and were not removed when installing the pilot. I really do not think it was the steering hose fitting that leaked. Is there someway the compensation/ low pressure return could have been transiently pressurized to point of leaking?

in theory, the compensation line never has high pressure....in theory...

It is possible for the compression fitting to pop or leak. if thats the case, the end needs to be recut and refitted.
I would suggest replacing it with a 5/16 1000 psi steering hose with Parker fittings

Also, make sure you have the vented fill plug. Thats what is supposed to leak when overpressured.

 

[dogdoc]

verified vented cap, mine has the hollow
of course the return line fitting is the most difficult to access

 

[dogdoc]

cleaning boat yesterday noticed small leak at port engine steering ram. must all be related to overfill and subsequent over pressure. will never do that again!

 

[seasick]

The helm should have vented way before that ram seal. Keep an eye on it.

 

[Holokai]

It sounds like a couple of possible issues working together. You could be good about it a fix them one at a time, test, and record results, or you could fix the known/probable issues and hopefully be done with it.

Return line fittings/the line itself as low pressure. It's a pain but would be good to check they were installed at the helm and AP pump with proper torque. Also, as mentioned, if cut to a custom length, the return line hose end could be less than perfect.

SeaStar ram seals are prone to leakage if there is any rough spot on the shaft. The good thing is that the seals are user-replaceable (google your ram model for the appropriate seal kit) and you can usually salvage the shaft by taking very high grit emery cloth and wet sanding any spots that catch on your fingernail.

While you're at it you might as well flush/purge the whole system since you've had multiple known leaks. A power purge makes a full flush/fill a lot faster but topping off can easily be done manually if you take your time. Don't forget to purge air from the AP pump/hoses by running it in NFU/manual mode when you're topping off the steering wheel/helm pump; depending on your specific installation the AP hoses can be prone to collecting air. I'll usually top off the system and run the AP/turn the wheel then do something else for an hour. I'll do this over the course of a few hours to let all the micro-bubbles accumulate into bigger ones as they travel faster to the high point/vent.

 

[dogdoc]

finally got back from up north and found hydraulic fluid that had leaked from helm on the deck and leaked fluid from port steering cylinder. put some fluid in and turned the wheel. the cylinder produced and steady stream of fluid and there was obviously air in the system. the cylinder was bad seals. the helm was coming from the return line and was my fault. due to a sharp bend at the fitting. should have used an elbow not bent the vinyl tube. since it is above the steering fittings could not get elbow in. added a 4in stainless nipple with an elbow then the compression fitting that gave a straight line for the tube. had a mechanic replace cylinder seals and bleed system with power bleed. 2 trips and no leaks and flawless auto pilot.
curious bleeding technique people use to manually bleed system