SIERRA MerCruiser Early GM Engine Coupler, Round Pattern – 18-2171

Description

SIERRA MerCruiser Early GM Engine Coupler, Round Pattern – 18-2171

Sierra 18-2171 is the round six-hole engine coupler used on numerous early MerCruiser GM engines. It mounts at the crankshaft/flywheel interface and accepts the stern-drive input yoke; it is specifically not the triangular three-bolt MR/Alpha/Bravo-style coupler.

• Round-pattern engine-to-stern-drive coupler for early MerCruiser GM engines.
• Overall diameter: approximately 4.5 in; bolt-circle diameter approximately 3-9/16 in.
• Six mounting holes and approximately 4.5 in overall length.
• Not for MR/Alpha/Bravo applications that use the triangular three-bolt coupler.
• Inspect engine alignment and input-yoke splines whenever a failed coupler is replaced to prevent repeat spline damage.

For marine drive and engine service parts, fitment can vary by model, serial number, gear ratio, casting and prior service history. Compare the original OEM number and physical configuration before installation, and replace related seals, bearings, locking hardware or cable components when their condition requires it.

Specifications

• Manufacturer: Sierra
• Part Number: 18-2171
• Application: Early MerCruiser GM inline-four, V6 and V8 applications using the round six-hole coupler and OEM 76850A2 / 32492A-series references; exclude applications requiring the triangular three-bolt coupler.
• Overall Diameter: 11.4 cm (4.5 in)
• Bolt Circle Diameter: 9.05 cm (3-9/16 in)
• Overall Length: 11.4 cm (4.5 in)
• Mounting Holes: 6
• Coupler Style: Round / hub style

Interchange / OEM References

• GLM: 11500
• Mallory: 9-72502
• MerCruiser Stern Drive: 32492A2, 32492A3, 32492A5, 38965A1, 38965A2, 76850A2