Sierra 18-2171 Engine Coupler, Replaces 76850A2, for GM Engines with Triangular 3-Bolt Coupler except MR/Alpha/Bravo
Sierra 18-2171 Engine Coupler, Replaces 76850A2, for GM Engines with Triangular 3-Bolt Coupler except MR/Alpha/Bravo
The Sierra 18-2171 Engine Coupler is a direct replacement engine coupler built for GM engines fitted with a triangular, 3-bolt coupler design, excluding MR/Alpha/Bravo drive configurations. It connects the engine flywheel to the transmission or outdrive, transferring rotational torque while accommodating minor misalignment between the engine and drive unit. Correct coupler fitment is critical: installing the wrong coupler pattern can prevent proper engagement with the drive and lead to premature wear or failure.
This coupler is manufactured from metal with a machined black finish, built to meet or exceed the quality of the original equipment part it replaces. It is a single-piece unit that cross-references directly to six OEM Mercury/Mercruiser part numbers, making it straightforward to identify as the correct replacement when servicing engines that use the triangular 3-bolt coupler pattern. Sierra engineers its couplers to hold up under the demands of high-horsepower marine engines operating in harsh, corrosive marine environments.
Use this coupler when servicing or replacing a worn, cracked, or damaged coupler on an eligible GM engine, or when rebuilding the engine-to-drive connection during an outdrive or transmission service.
Specifications
- Brand: Sierra
- Manufacturer Part Number: 18-2171
- Material: Metal
- Color: Black
- Exterior Finish: Machined
- Connector Type: Coupling
- Thread Type: NPT
- Item Dimensions: 5.2 x 5.1 x 4.9 inches
- Weight: 3.63 pounds
- Number of Pieces: 1
- UPC: 030999311757
Fitment
- All GM engines except MR/Alpha/Bravo with a triangular, 3-bolt coupler
Replaces (OEM)
- 32492A2
- 32492A3
- 32492A5
- 38965A1
- 38965A2
- 76850A2
Frequently Asked Questions
What does the Sierra 18-2171 Engine Coupler fit? It fits all GM engines except MR/Alpha/Bravo configurations that use a triangular, 3-bolt coupler pattern. Check your existing coupler's bolt pattern before ordering to confirm compatibility.
What OEM part numbers does the 18-2171 replace? The Sierra 18-2171 replaces OEM numbers 32492A2, 32492A3, 32492A5, 38965A1, 38965A2, and 76850A2.
Will this coupler work with an Alpha or Bravo outdrive? No, the 18-2171 is specifically excluded for MR, Alpha, and Bravo drive configurations; it is intended for GM engines using the triangular 3-bolt coupler pattern instead.
What are the dimensions of the 18-2171 coupler? The coupler measures 5.2 x 5.1 x 4.9 inches.
How much does the Sierra 18-2171 weigh? It weighs 3.63 pounds.
What material is the engine coupler made from? The 18-2171 is made from metal with a machined black finish for durability in marine service.
Is the Sierra 18-2171 a genuine OEM part or an aftermarket replacement? It is an aftermarket coupler manufactured by Sierra to meet or exceed the specifications of the original equipment coupler it replaces, including 76850A2 and the other listed cross-references.
How many pieces come in the package? The 18-2171 ships as a single one-piece coupler unit.
How is the 3-bolt coupler pattern different from other coupler types? The 18-2171 uses a triangular 3-bolt bolt pattern, which is a different mounting configuration than couplers used on MR/Alpha/Bravo drives, so the two are not interchangeable.
What is the UPC for the Sierra 18-2171? The UPC for the Sierra 18-2171 Engine Coupler is 030999311757.
When would I need to replace the engine coupler? The 18-2171 should be replaced if the existing coupler on a compatible GM engine is worn, cracked, or damaged, or during a transmission or outdrive service where the coupler is inspected.