Sierra 18-6273-1 Tilt/Trim Motor, Replaces 99186, Fits 35-220 HP Mercury/Mariner Outboards 1985-93

The Sierra 18-6273-1 is a high performance cartridge pump tilt/trim motor with a replaceable motor, built to power the tilt/trim system on 35-220 HP Mercury/Mariner outboards (1985-93) equipped with Design I, 3 Ram, 3 Wire tilt/trim units and a side fill reservoir as part of the Integral Trim/Tilt System. It drives the hydraulic pump that raises and lowers the outboard, restoring tilt/trim function when the original motor has worn out or failed. The housing uses aluminum and stainless steel construction for corrosion resistance in marine environments, and the unit is finished in white to match Mercury/Mariner outboard hardware.

This motor operates with relay 18-5737, which is a separate component and is not included with this pump motor. As a Sierra replacement part, it is built to meet or exceed the performance of the original equipment motor it replaces, giving boat owners a reliable way to restore tilt/trim operation without sourcing a full OEM assembly. Confirm your outboard's HP rating and tilt/trim system type (Design I, 3 Ram, 3 Wire, side fill reservoir) before ordering to ensure correct fitment.

Specifications

• Brand: Sierra
• Manufacturer Part Number: 18-6273-1
• Color: White
• Material: Aluminum, Stainless Steel
• Weight: 6.54 pounds
• Horsepower Range: 35-220 HP
• Tilt/Trim System Type: Design I, 3 Ram, 3 Wire, Side Fill Reservoir, Integral Trim/Tilt System
• Relay Required: 18-5737 (sold separately)
• OEM Cross Reference: 99186, 99186-1, 99186-T
• Recommended Use: Salt Water
• UPC: 808282186883

Fitment

• 35-220 HP Mercury/Mariner Outboards (1985-93)
• Design I, 3 Ram, 3 Wire Tilt/Trim Units with Side Fill Reservoir, Integral Trim/Tilt System

Replaces (OEM)

• 99186
• 99186-1
• 99186-T

Frequently Asked Questions

What does the Sierra 18-6273-1 tilt/trim motor replace? The Sierra 18-6273-1 replaces Mercury 99186, 99186-1, and 99186-T tilt/trim motors.

What outboards does the 18-6273-1 fit? It fits 35-220 HP Mercury/Mariner outboards (1985-93) equipped with Design I, 3 Ram, 3 Wire tilt/trim units and a side fill reservoir as part of the Integral Trim/Tilt System.

Is a relay included with this tilt/trim motor? No, the Sierra 18-6273-1 uses relay 18-5737, which is a separate part and is not included with the motor.

What is the 18-6273-1 tilt/trim motor made of? Sierra builds the 18-6273-1 from aluminum and stainless steel for corrosion resistance in marine use, including salt water.

How much does the 18-6273-1 weigh? The Sierra 18-6273-1 tilt/trim motor weighs 6.54 pounds.

What color is the Sierra 18-6273-1 motor? It is finished in white.

Is the Sierra 18-6273-1 a genuine OEM part or aftermarket? The 18-6273-1 is a Sierra aftermarket replacement built to meet or exceed the performance of the original Mercury 99186 series motor it replaces.

Does the 18-6273-1 come with a cartridge pump? Yes, the 18-6273-1 is a high performance cartridge pump tilt/trim motor with a replaceable motor.

Will the 18-6273-1 fit any Mercury tilt/trim system? No, it is designed specifically for Design I, 3 Ram, 3 Wire tilt/trim units with a side fill reservoir on 35-220 HP Mercury/Mariner outboards (1985-93); other tilt/trim configurations require a different motor.

What is the horsepower range for the 18-6273-1? The Sierra 18-6273-1 covers 35-220 HP Mercury/Mariner outboards.

Does the 18-6273-1 work on Mariner outboards as well as Mercury? Yes, the 18-6273-1 fits both Mercury and Mariner outboards within the 35-220 HP range (1985-93) that use the Design I, 3 Ram, 3 Wire side fill system.