Why is my outboard steering hard to turn?

Steering hard to turn / stiff steering · Symptom: The wheel is stiff or binds when you turn it, the outboard steers harder in one direction, or hydraulic steering feels spongy or has extra free play.

Quick answer: On cable (mechanical) steering, the most common cause is old, hardened grease or corrosion inside the engine's tilt tube, where the steering cable's ram slides in and out. To test, disconnect the link arm at the engine: if the motor now turns easily by hand, the problem is the cable and tilt tube. Clean the tube and the ram, then re-grease both with water-resistant marine grease. If the motor is still stiff with the cable off, check the engine's swivel bracket and grease points. If you have hydraulic steering, check the helm fluid level and look for leaks. Spongy steering usually means air in the system, so it needs bleeding.

Likely causes (most to least common)

Cable steering: dry or hardened grease, salt, or rust in the tilt tube or on the cable's telescoping ram
Engine swivel bracket or steering pivot not greased (check the grease points in your owner's manual)
Worn, kinked, or cracked steering cable, or a binding helm
Hydraulic steering: low fluid, air in the system, or a leaking hose or cylinder seal
Wrong fluid in a hydraulic system, or a kinked hydraulic hose
Loose or wrong fasteners on the link arm or cable nut (a safety risk, not just stiffness)

Safe owner checks & fixes

Do the checks on the trailer or at the dock, never while underway. Mercury's manuals list "check steering system for binding" and hydraulic fluid and leak checks as before-each-use items.
Cable steering: remove the link arm and see whether the motor turns freely. If it does, loosen the cable nut and slide the ram out of the tilt tube.
Clean the inside of the tilt tube and use a brass wire brush on the ram to remove old grease and corrosion. Then lubricate both with water-resistant marine grease and reassemble. If the tube is badly corroded, it may need to be replaced.
Check the cable's outer jacket. A cracked jacket or a cable that's still stiff when disconnected from the motor means the cable (or helm) needs to be replaced; these parts aren't meant to be repaired.
Reassemble with the original locking nuts and bolts. SeaStar/Dometic warns that regular nuts can vibrate loose and cause loss of steering. Make sure the cable nut is fully tightened on the tilt tube.
Hydraulic steering: check the helm fluid level, look for leaks at the hoses, fittings, and cylinder, and top up only with the fluid the steering maker specifies. If steering is spongy or has lots of free play, bleed the system following the manufacturer's procedure (SeaStar says it takes two people).
Grease the engine's steering and swivel grease points as shown in your owner's manual, especially if you boat in salt water.

Parts / tools

Water-resistant marine grease and grease gun, brass wire brush, wrenches, rags, the correct hydraulic steering fluid (if equipped), owner's manual.

Call a marine mechanic when

The cable is stuck in the tilt tube; the helm or cable binds even when disconnected; there's a hydraulic leak you can't find or fix; the steering has sudden free play or you lose steering; or any steering fastener is missing or damaged. Don't go out with steering that binds. If you lose steering on the water, slow down and call TowBoatUS/Sea Tow or the Coast Guard (VHF 16).

Sources

Values not stated here are model-specific; check your owner's manual.