Sierra 18-2172 Engine Coupler, Replaces 14505A2, for GM V6/V8 Engines with Triangular 3-Bolt Coupler

The Sierra 18-2172 Engine Coupler is a triangular, 3-bolt engine coupler built for GM V6 and V8 marine engines, excluding MC-I, Alpha, and Bravo drive applications. It is the direct replacement for OEM number 14505A2, and also cross-references to 38965A1, 38965A2, and 76850A2.

This coupler is used specifically when converting an engine that has a 2-piece rear main seal with a 3-1/2 inch crankshaft bolt pattern over to a newer engine design that uses a 1-piece rear main seal with a 3 inch bolt pattern. The triangular, 3-bolt hole layout matches the mounting pattern required for this rear main seal conversion, allowing the coupler to bridge the two bolt patterns correctly.

The 18-2172 is round in shape with a white finish and weighs 3.88 pounds. Sierra states that this part meets or exceeds the performance of the original equipment part it replaces, and it is backed by Sierra's limited warranty.

Specifications

• Brand: Sierra
• Manufacturer Part Number: 18-2172
• Coupler Type: Triangular, 3-Bolt
• Application: Converts 2-piece rear main seal engine (3-1/2 inch crankshaft bolt pattern) to 1-piece rear main seal engine (3 inch bolt pattern)
• Shape: Round
• Color: White
• Weight: 3.88 pounds
• UPC: 030999562463

Fitment

• All GM engines except MC-I, Alpha, and Bravo applications, with triangular, 3-bolt coupler

Replaces (OEM)

• 14505A2
• 38965A1
• 38965A2
• 76850A2

Frequently Asked Questions

What does the Sierra 18-2172 engine coupler replace? It replaces OEM number 14505A2, and it also cross-references to 38965A1, 38965A2, and 76850A2.

Which engines is the 18-2172 coupler designed for? The Sierra 18-2172 fits all GM engines except MC-I, Alpha, and Bravo drive applications, and is built for a triangular, 3-bolt coupler pattern.

When would I need this coupler instead of the original one? This coupler is needed when replacing a V6 or V8 engine that has a 2-piece rear main seal with a 3-1/2 inch crankshaft bolt pattern with a newer engine that has a 1-piece rear main seal and a 3 inch bolt pattern.

How much does the 18-2172 coupler weigh? The Sierra 18-2172 engine coupler weighs 3.88 pounds.

What shape and color is the coupler? The 18-2172 coupler is round in shape with a white finish.

Is the Sierra 18-2172 coupler a direct OEM replacement? Yes, it is a direct replacement for 14505A2 and cross-references to 38965A1, 38965A2, and 76850A2, matching the original triangular 3-bolt mounting pattern.

What is in the box with the Sierra 18-2172? One Sierra 18-2172 engine coupler, identified by UPC 030999562463.

Does the Sierra 18-2172 meet OEM performance standards? Yes, Sierra states that the 18-2172 meets or exceeds the performance of the original 14505A2 equipment part it replaces.

Can I use the 18-2172 on Alpha or Bravo drive engines? No, the 18-2172 is designed for GM engines and specifically excludes MC-I, Alpha, and Bravo drive applications.

Is the Sierra 18-2172 covered by warranty? Yes, the 18-2172 is covered under Sierra's limited warranty that applies to Sierra parts.

What UPC does the 18-2172 coupler use? The Sierra 18-2172 engine coupler carries UPC 030999562463.

Why does a 2-piece to 1-piece rear main seal conversion need a different coupler? Because the crankshaft bolt pattern changes from 3-1/2 inch to 3 inch between the two rear main seal designs, and the 18-2172's triangular, 3-bolt pattern bridges that difference.