861839A3 Mercruiser Coupler | Genuine Used Part

🔧 Product Description

Genuine MerCruiser 1.7L / 2.0L Diesel Sterndrive Coupler - Part Number: 861839A3

A genuine used MerCruiser engine coupler for selected 1.7-litre and 2.0-litre inline four-cylinder diesel sterndrive engines.

The coupler bolts to the engine flywheel and transfers diesel-engine torque to the sterndrive input shaft through its splined centre. It was designed specifically for the compact MerCruiser 1.7 DTI and 2.0 EI / ES diesel families.

⚙️ Key Features

• Genuine MerCruiser diesel engine coupler
• Correct Mercury reference 861839A3
• Designed for compact inline four-cylinder diesels
• Transfers flywheel torque to the sterndrive input shaft
• Fits selected 1.7L and 2.0L MerCruiser diesel packages

🚤 Compatibility

Commonly used on

• MerCruiser 1.7L DTI diesel sterndrives
• MerCruiser 1.7 MI and 1.7 MS engines
• MerCruiser 2.0 EI and 2.0 ES diesel packages

Typically suits

• Engine models and serial ranges:
• MerCruiser 1.7 MI 120 inline four-cylinder - serial 88109041 and up
• MerCruiser 1.7 MS 120 inline four-cylinder - serial 8810800 and up
• MerCruiser 1.7L DTI - serial 0M055000 through 0M999999
• MerCruiser 2.0 EI 115 - serial 88200000 onward in the listed ranges
• MerCruiser 2.0 EI 130
• MerCruiser 2.0 EI 150
• MerCruiser 2.0 ES 130
• MerCruiser 2.0 ES 150
• MerCruiser 2.0 ES 170
• Engines whose flywheel-housing diagram specifies coupler 861839A3
• HP Range: 115HP - 170HP
• Engine Type: Inline four-cylinder turbo-diesel marine engine
• Year Range: Engine and serial-number controlled

🔌 Function

The coupler transfers rotation from the diesel flywheel to the sterndrive input shaft while damping engine torsional pulses and gear-engagement shock.

⚠️ Common Signs of Failure

• Engine runs but drive input is lost
• Splines are stripped or heavily worn
• Rubber or damping material separates
• Knocking from the flywheel housing
• Excessive vibration under load
• Coupler overheats or produces a burning smell
• Input shaft is difficult to align
• Repeated failure caused by incorrect engine alignment

🔄 Supersession & Cross Reference

OEM Supersession Chain

• 861839A3 current Mercury service reference for the applicable diesel coupler

OEM / Related Numbers

• 861839A3
• 861839A 3
• Flywheel-cover and coupler hardware from the 1.7L / 2.0L diesel assembly
• Related driveshaft assembly: 862772A28 on specified 1.7 DTI installations
• Coupler mounting hardware from the applicable engine serial range

Aftermarket / Verified Equivalents

• No aftermarket equivalent

📦 Condition

• Genuine used part
• Removed from running engine where applicable
• In good working condition unless otherwise stated