2001 Mercury Mariner 50-60HP Factory Service Manual, Page 21Get this manual
MAINTENANCE
Steering Link Rod Fasteners
WARNING
Disengagement of steering link rod can result in the boat taking full, sudden, sharp turnThis potentially violent action can cause occupants to be thrown overboard exposing them to serious injury or deathIMPORTANT: The steering link rod that connects the steering cable to the engine must be fastened using special washer head bolt ("a" Part Number 10-90041) and self locking nylon insert locknuts ("b""c" Part Number 11-34863)These locknuts must never be replaced with common nuts (non locking) as they will work loose and vibrate off, freeing the link rod to disengage