Hydraulic steering issue - HELP!!

rogerbum

All, I'm in Tofino for a fishing trip. I had an issue with the hydraulic steering today. I have a SeaStar 1.1 unit with a single helm station. I was backing away from the dock in heavy current (maybe 12kt's - it was so heavy I couldn't get untied without backing off against the lines). When I went hard over and gave a good bit of reverse throttle to get away from the dock, the filler tube cap (the one on the top of the helm station), blew off and I spewed about 1-2 oz. of hydraulic fluid in the cabin. Fortunately, I was looking out the back while pulling away from the dock and didn't get a face full or would have had a very hard time seeing in a fairly critical moment in time. Once I was safely away from the dock, I found the parts that flew off (the black plastic cap, an o-ring and a rubber like button (that I believe should be the venting part) and reassembled them the way I think they were in. The metal part for the fill cap remained attached to the helm. The steering seemed to be operating fine and did so for the remainder of the day. On the way back into the dock, the current was again in the same direction so once I got the bow to the dock I had to do a fairly hard reverse to stop the boat and crank the wheel over to bring the stern back to the dock. Again, the cap blew off and another ounce or two came out.

I was able to go to a local marine store and purchase hydraulic fluid and a replacement cap. The cap that was on there has had the plastic blown off the top and the 2nd time I couldn't relocate the o-ring that is internal to the venting cap. Until I bought the new cap, it wasn't apparent to me that the plastic part should never come off the metal part that threads into the fill port. So questions:

1) Have you ever seen this happen before? I have the manual and can read so I'm sure I can add new fluid and bleed the system. My suspicion is that it will work fine except in the odd circumstance of when I'm back at high power and have the engines hard over. Given that I've only lost a few ounces, I don't think it will be too hard to fill and bleed. However, I'm not sure if I should re-fill and bleed. What do you think?

2) What do you think caused the problem? My suspicion is that when I'm hard over and applying hard reverse throttle, I have a lot of pressure on the ram in a way that is unusual. However, I'd think that the system should be able to hand that. Once I refill and bleed, I will check the seals on the ram for leaks. I haven't seen any indication of fluid leaks near the engines but it's possible.

3) What else should I do or check?

4) If the hydraulic system fails will I lose steering completely or will it be more like power steering on a car - e.g. just really difficult? With the currents they have at the dock here in Tofino, a complete loss of steering could result in major damage to my boat and others around me if it happens at an inopportune time.

journey on · Posted: Thu Jun 21, 2012 11:17 am Post subject:

Roger, I don't think you have anything to worry about.

Remember, that helm is nothing but a bidirectional pump with check valves to route the flow out of the helm, back to the correct side of the cylinder. And a reservoir at the top.

So here's my theory. When you left the dock, the current and motor thrust put a lot of back pressure on the hydraulic line, causing some of the fluid to flow back into the helm reservoir and out the fill/vent. Once you were going straight, the pressure was reduced to normal levels and everything was normal. Unless you blew out more fluid than the reservoir held, no air got into the system. Certainly you will soon know this, if not already.

Clayquot Sound is a beautiful place to cruise. And good fishing.

Boris

rogerbum · Posted: Thu Jun 21, 2012 11:34 am Post subject:

Well, now that I've had time to read the manual and learn about hydraulic steering, I understand how the system works. In addition I rec'd an email from Les at EQ that was helpful. So at least I now know that I'm the hydraulic steering is unlike power steering on a car and that all the steering is taking place via the hydraulics (e.g. no other mechanical connection). So if it does fail entirely, I would be screwed. However, based on my experience with it working all day yesterday after the first blowout, I don't think it's likely to fail entirely. Still Les has never seen or heard of this kind of issue and suggested I call Teleflex/Sea Star tech support. I have a call into them and they claim to respond in 1 hr under most circumstances.

TyBoo · Posted: Thu Jun 21, 2012 12:07 pm Post subject:

All I know is that if you lose your fluid you lose steering. The wheel will spin free and the ram will float freely. I redid my hoses the other day (same system) and added some tubing with braided stainless sleeves between the cylinder and the OEM hoses to eliminate a kink. Until the fluid was refilled and the air bled out there was no steering connection.

Need me to send Jamie up? She's real good at turning the wheel while you close the bleeders.

beermanPDX · Posted: Thu Jun 21, 2012 12:18 pm Post subject:

Did your blowout happen as you were actively turning the wheel (activating the pump)? When you are actively turning the wheel, the one check valve is open so any pressure in the return line should just continue to flow through the system.

When you are not actively turning / operating the pump, both check valves should be closed so any pressure on the ram in the cylinders would be forced through the return line in to the pump. I'm guessing this is what was going on when you blew your cap.

How full was your helm pump? Did you have the proper amount of airspace at the top (~1/2")?

starcrafttom · Posted: Thu Jun 21, 2012 12:45 pm Post subject:

I agree with rob, You may have had too much fluid in the system and it blew. If the steering is working now I would not add more. A ounce of two out of how much in the system? should not cause you to loose steering. check you head space ( amount of air at the top of the fill) and see if you are at the right level.

TyBoo · Posted: Thu Jun 21, 2012 1:54 pm Post subject:

If you fill and bleed the helm per the instructions the helm will be full. No real air space is needed or wanted. All that happened is that the external forces on the motors were great enough to overcome the pressure relief setting and oil was forced thru the return side without a like amount of oil going out the pressure side. The helm couldn't hold it all and the vent cap couldn't resist the building pressure in the helm.

Roger, remember - It is Pascal's Law, not Pascal's suggestion.

Captains Cat · Posted: Thu Jun 21, 2012 2:18 pm Post subject:

Roger, read this old thread.

http://www.c-brats.com/viewtopic.php?p=220971#220971

Describes the same problem (I think) experienced by Matt Unique.

Charlie

TyBoo · Posted: Thu Jun 21, 2012 2:21 pm Post subject:

I believe the pressure in the system is 600 psi. Using the fancy math stuff you learned in all your years of school you can calculate how hard you have to push on the sides of your motors to duplicate your experience. The cylinder becomes the pump so figure out the piston area minus the rod area and you can find how hard to push on the rod to develop 601 psi. The leverage and moment and all those other fancy words to convert motor side force to pushing on the rod force are beyond me, so good luck there.

Have you ever noticed when your motor is turned all the way to the stops (or end of cylinder stroke) you can still force the wheel to turn? That's the relief valve being overcome. It is to protect the system. It may be that you require a helm pump with a higher relief setting, and your reply from Teleflex may well suggest that. They set a horsepower limit on the design of their steering systems and they might even give you some help with a replacement if the recommended pump is inadequate. What happened to you is within the realm of what is supposed to happen given the fact that the other option is something breaking causing a complete loss of steering control.

Sea Wolf · Posted: Thu Jun 21, 2012 2:26 pm Post subject:

beermanPDX · Posted: Thu Jun 21, 2012 3:16 pm Post subject:

Captains Cat · Posted: Thu Jun 21, 2012 3:49 pm Post subject:

TyBoo · Posted: Thu Jun 21, 2012 4:50 pm Post subject:

thataway · Posted: Thu Jun 21, 2012 4:50 pm Post subject:

Surprised that Les had not heard of this, since similar situations have been posted on this forum at least several time. I had total steering failure under a similar set of circumstances on the Tom Cat (a hard back up). This summer I also reported that I started with the outboard centered and up when trailering, and a few days into the trip we noted a fair amount of hydraulic fluid on the floor, leaking from around the cap. The motor had fallen to one side.

As I see the issues, the helm pump on the Sea Star units does not have adequate back pressure valves, and when torque or some other force, such as going down Calif. Highways, with pot holes, causes the motor to go to one side, these valves leak.

In the case with the Tom Cat it was obvious that some seals had blown, and the helm pump was damaged. I think that on the 22, the help pump is still OK.

The moral is that you cannot exert back pressure on the rams, and expect the Sea Star helms to withstand that pressure. As to if any internal seals are damaged, only time will tell.

For now keep running the boat, but I would have another helm--and if possible upgrade to the next size. Yes, if the helm pump fails, you are down to lashing a boat hook to the outboard and tiller steering.

I don't know the limits of the Sea Star System, but in my larger boats there were relief valves which would yield at 1000 to 1200 lbs pressure. One way of testing the ram was to put an 8 foot emergency tiller in place and seeing if you could overcome the seals on the rams, without opening the bypass valve.

If there is some other way of getting off the dock, I would be exploring it. Repeating this, is going to do damage to the helm pump.

beermanPDX · Posted: Thu Jun 21, 2012 5:00 pm Post subject: