Hydraulic Steering: Check Fluid, Bleed Air and Fix Stiff or Loose Steering

With the engine off, look along both hoses from the helm to the cylinder. Look for wet spots, drips, chafing, kinks and hoses rubbing on sharp edges. Check the fittings at the helm and cylinder and the seals where the cylinder rod comes out. Wet, oily dirt is a sign of a slow leak.

At the engine, grab the cylinder and the steering arm and try to wiggle them. Nothing should clunk or move except the steering itself. Check that every bolt and locknut is present and tight, including the bolt that attaches the cylinder to the engine's steering arm. On twin engines, check the tie bar ends too. A loose bolt here is a real danger; tighten to your manual's torque or have a pro do it.

Center the engine. If your system has an unbalanced cylinder (common on inboards; your manual says if yours is one), the cylinder rod must be fully retracted while you check, or the reading will be wrong. Remove the fill plug on top of the helm (on dual-station boats, use the highest helm).

The level is usually correct when the fluid is just below the filler threads. For SeaStar helms, Dometic gives about 1/8 to 1/4 inch below the lowest thread of the fill port; other brands and helm angles differ, so check your manual. If you can't see fluid at all, add some and plan to find the leak.

While the plug is out, look at the fluid itself. Dometic suggests drawing a little out of the helm with a clean syringe: fluid that looks like chocolate milk has water in it. That means a leak somewhere is letting water in, and the system needs the leak fixed and a thorough flush with fresh fluid, usually by a shop. Water left inside corrodes the helm and cylinder from within.

Add only the fluid your steering manufacturer specifies. Dometic recommends SeaStar fluid only and warns that a non-approved fluid can damage the system. Add a little at a time. Don't overfill: fluid expands when it warms up and will leak out of the vented cap. Reinstall the plug snug, not tight.

Turn the wheel from hard over to hard over several times while watching the fluid in the helm. If the level rises and falls as you turn, or bubbles come up, there is still air in the system. Count the turns lock to lock and compare with your manual; too many turns usually means air. The engine should start to respond within about a quarter turn of the wheel; a bigger dead spot points to air or low fluid. Also check steering at different tilt positions on an outboard to be sure the hoses don't bind.

If there is air, you need to bleed the system. The basic method for a single-helm, single-cylinder outboard system is shown below; dual helms, autopilots and power assist need extra steps from your manual.

Screw the filler kit onto a bottle of steering fluid. Remove the helm fill plug and screw in the other end of the filler tube. Hang the bottle upside down above the helm and cut the bottom off so it can act as a funnel. Push clear tubing onto both bleeder fittings on the cylinder and run them into a catch container.

Have your helper turn the wheel until the cylinder is fully extended to one side. Open the bleeder on the side your manual specifies, usually a fraction of a turn. Hold the cylinder still while the helper turns the wheel the other way. Air and fluid will come out of the tube.

When the fluid in the tube comes out clear with no bubbles, close that bleeder while the helper keeps turning. Watch your fingers: the cylinder moves as soon as the bleeder closes.

Now open the other bleeder, hold the cylinder and have the helper turn the wheel in the opposite direction. Close the bleeder when no more bubbles appear.

Keep an eye on the bottle the whole time. If the fluid drops below the filler tube, air gets pulled back in and you'll have to start over. Top it up with fresh fluid. Don't reuse fluid from the catch container unless your manual allows it.

Remove the filler kit and set the fluid level as in step 3. Turn hard over to hard over again and watch the helm. If the level still moves, repeat the bleed. Check the bleeder fittings for leaks; a bleeder that keeps leaking after it is snug needs replacing.

On outboard systems, the cylinder slides on support rods that pass through the engine's tilt tube. Rinse the cylinder with fresh water only; Dometic warns against cleaners with ammonia, acids or other harsh ingredients. Wipe the rods and apply a thin coat of marine grease where your manual shows. Stiff steering that improves after this was dry or corroded support rods.

Run a fingertip around the seal (gland) at each end of the cylinder and around each hose fitting. Fluid on your finger means a weeping seal or fitting. A fitting may stop if snugged gently; a weeping gland needs new seals (SeaStar sells gland kits, and handy owners can fit them by following the instructions exactly) or a shop. Check the cylinder rod for salt crust, nicks and scratches, which chew up seals. SeaStar's advice is to pull the support rod once a year, clean the old grease and dirt out of it and the tilt tube, and regrease, and to rinse the cylinder with fresh water after every saltwater trip.

Test steering at the dock first, then at low speed in open water. The wheel should turn smoothly with no dead spot, and the boat should respond right away. Recheck the fluid level and look for leaks after the trip.

Many smaller outboards use a push-pull cable instead of hydraulics. Signs of a failing cable: steering that gets harder each season, binding at one end of travel, rust at the tilt tube, or a cracked cable jacket.

• Grease the cable end and tilt tube through the grease fitting if there is one. Turn the wheel so the cable end is fully pulled back into the tilt tube before you grease it; greasing with it extended can lock the cable with trapped grease.
• Don't try to force a stuck cable out of the tilt tube by cranking the wheel; that can damage the helm.
• Lubricating a stiff cable is a stopgap. BoatUS calls replacement the preferred fix, and a cable that binds can fail without warning. If your cable steering is worn out, it is often a good time to consider upgrading to hydraulic.