Caring For Your Hydraulic Steering
By Bill Parlatore
What you should know about this often overlooked marine system.
An annual inspection of your hydraulic steering system starts at the helm, where the oil reservoir is located.
Some marine systems are so reliable we tend not to notice them. I've owned a few boats in my time, and most of them had hydraulic steering. It's one of those reliable systems so widespread, it's all but universal except for boats that use a tiller, cable, or other form of mechanical steering. Good steering systems work as they should, year after year, and typically don't get on the schedule of routine maintenance, unless there is a problem.
But that might not be the best of ideas. After all, it is on a boat, and nothing on a boat is perfect, or forever. Does the hydraulic fluid go bad over time? Do fittings work loose? Are there any common failure points you should know about? So, how often should you think about these things and what exactly do you look for? To find some answers, we spent time with Chad Winget, lead technician at Zimmerman Marine, a well-respected service and repair facility in Deltaville, Virginia, whose ABYC-certified tech staff knows how things should be done. When we got together, he explained hydraulic steering in simple terms and showed what to look for and how best to ensure a trouble-free system, no matter what kind of boat it's on.
Hydraulic steering is made up of three components: a pump with an integral reservoir for hydraulic oil, a ram that connects to a rudder or outboard engine, and connecting lines that transmit inputs from the steering pump to the steering ram. It's very simple and, when sized and installed correctly, makes for a mostly carefree system. Turning the steering wheel in either direction pumps oil through the lines to the ram, which in turn pulls or pushes the rudder, outboard, or sterndrive in the desired direction.
The simplest example of hydraulic steering is found on small powerboats powered by single outboard or multiple engines linked by a tie bar. On a small boat, a compact hydraulic pump with integral hydraulic-fluid reservoir located at the steering wheel connects with sturdy nylon hoses below decks and in turn to flexible rubber hoses to a steering ram at the transom, which reliably turns the outboard(s) as one turns the steering wheel. Steering systems get progressively more complicated on larger boats with multiple helms, autopilots, and power steering, but the basics are much the same. So, too, is the maintenance.
Winget recommends a yearly inspection. Look at the seals on the ram, especially on an open boat, where it's exposed to salt, sand, fishing line, and other potential hazards. The shaft should never be wet with oil. If it is, wipe it dry with a rag and check it again as you turn through a steering cycle. If a wet shaft comes out of the ram, the seals are leaking and need to be replaced. Check to see there is no pitting on the shaft, a sign of corrosion that will ultimately cause hydraulic fluid to leak out of the cylinder.
Tips: In an emergency, 5W motor oil will work well enough in your hydraulic system to get you home.
Remove the vented cap on the hydraulic reservoir at the helm and take a sample of the hydraulic oil. Does it look black? Does it smell? Hydraulic steering fluid is clear, mostly odorless, and light-colored. It's specially formulated with viscosity stabilizers, anti-wear and anti-foaming agents, and corrosion inhibitors. It is the best oil to use in hydraulic-steering systems, but any oil that meets MIL 5606 specification can be used, and in an emergency, even 5W engine oil. While many boaters use automatic transmission fluid in their steering systems, using the manufacturer's recommended product is the way to go.
If the hydraulic steering oil sample contains dirt or is otherwise contaminated, the entire system should be flushed and the hydraulic oil replaced. Abrasive dirt is the biggest killer of hydraulic systems. It often comes from debris during the initial installation of the steering system. Dirt or dust can enter the system when hoses are cut and fittings installed. It's best to flush out a steering system before the final hydraulic oil goes in, something to consider when making a repair. Your hydraulic system should be flushed out and oil replaced every five years, including thoroughly bleeding the system to remove air bubbles. Many service yards use portable purging systems that make this a quick and foolproof job that just takes minutes.
The ram should never be wet. If it is, wipe it dry and check it again after turning the wheel lock to lock.
Tips: A spongy wheel indicates you have a hydraulic leak. oil doesn't evaporate, so if the reservoir is low, a leak is present.
Spend a moment at the helm. Is there any oil visible around the seals behind the wheel? Does the wheel feel spongy when turned? It may have air in the system, which needs to be bled out. If the system was previously purged and all air removed from the lines, this may be a sign that there's a leak somewhere. A spongy wheel may also indicate the ram or steering pump is leaking internally, which you may not readily see. If you once enjoyed three-and-a-half turns lock to lock, and now it's five turns, you have a leak. Oil doesn't evaporate, nor is it consumed by use. So if you have to add oil to the reservoir, you have a leak.
Check the hoses and connections between the helm and the ram with a clean rag. Is there any wetness at the connections? The nylon plastic hoses that snake their way aft to the steering ram can get brittle and crack over time, though they typically are protected from the elements for this reason. It's the flexible rubber hoses that are most exposed, but also easy to inspect.
Take a look once a year and you should be good to go. On bigger boats this yearly inspection takes a bit more time, but the process is the same.
We also checked in with Aldo Mastropieri, project manager of marine steering at SeaStar Solutions, an industry leader of hydraulic steering systems in recreational boats. He reiterated all of the earlier maintenance points covered and the value of a yearly inspection or every 200 hours of operation. He said SeaStar doesn't have a specific policy for replacing oil at regular intervals, but rather "as necessary" based on analysis of an oil sample from the reservoir. It does not go bad on its own, but if it is black or smells bad, replace the oil.
"Steering is all about how it feels," he says. How much effort does it take to steer a boat? It should not be hard or imprecise. SeaStar's current focus is on the future of marine steering, the integration of electronics into modern steering solutions. Electrohydraulic steering is a perfected technology and the direction the industry is taking. An electronic helm steers the boat through fly-by-wire signals to turn a pump on and off, and the hydraulics are now considered the "back end" of the steering system. Drastically shorter hydraulic lines are well-protected near the rudders or engines, controlled by signals transmitted by wire from whichever helm is operational. Adding a second steering station is simply another set of wires to be run, nowhere near the complexity of traditional hydraulic steering.
Given the huge opportunity for aftermarket replacement systems, Mastropieri sees recreational boating moving away from fully hydraulic steering systems in favor of the greater control and flexibility of electrohydraulic steering.
Mastropieri commented that the company's service center no longer recommends replacing parts in any steering system older than 10 years. As rubber ages, seals wear out and system components get hard and brittle. SeaStar advises its clients to consider replacing and/or upgrading their steering system to one of the newer solutions that use electronics.
Undertaking such a project is not difficult and is a viable solution for anyone with steering issues on an older boat. It's also within the realm of a DIY project, particularly attractive to those who own boats built in the '70s and &'80s, which are prime candidates for upgrading from older hydraulic or mechanical steering.