Sierra Piston Ring Set 18-3937 - Replaces GM 14089025, Mercury Marine 39-17464 - 8.9L 575 Marine Engines

The Sierra 18-3937 Piston Ring Set is a forged aluminum, recessed-head piston ring set built for the 8.9L 575 marine V8 engine family (540 cid, 8-cylinder), covering the 1986-1992 engine range. This is the standard (STD) size set, supplied complete with piston rings and wrist pin so it is ready to install without sourcing additional small parts separately. The forged aluminum construction with a recessed head design is engineered to handle the heat and load cycling of a marine inboard/sterndrive engine, giving a longer service life than a lower-grade cast replacement in this application.

Because marine engines in this family were sold and serviced across multiple brands, the 18-3937 set directly cross-references to GM, Mercury Marine, Mercruiser, OMC, and Volvo Penta piston ring part numbers, so it is a straightforward direct replacement whether the boat's engine data plate shows one of those brand names. Each Sierra piston ring set is manufactured to meet or exceed the original equipment part it replaces. Related part numbers 18-3939 and 18-3938 are also available in the same engine family for other bore sizes; confirm the size stamped on your original pistons before ordering to be sure 18-3937 (STD) is the correct set for your engine.

Specifications

• Brand: Sierra
• Manufacturer Part Number: 18-3937
• UPC: 030999975997
• Weight: 0.15 pounds
• Material: Forged Aluminum
• Head Design: Recessed Head
• Size: STD (standard)
• Engine Family: 8.9L 575
• Displacement: 540 cid
• Cylinders: 8
• Year Range: 1986-1992
• Contents: Piston rings and wrist pin, sold individually (one set per rod)

Fitment

• 8.9L 575 marine engine, 540 cid, 8-cylinder, 1986-1992

Replaces (OEM)

• GM 14089025
• Mercury Marine 39-17464, 39-34988, 39-65153, 39-67123
• Mercruiser F328506, F3892364, FI1100386, FI1100692, FI1101321
• OMC 328506, 3853268, 3853960, 914555, 985083, 986336
• Volvo Penta 3853268, 3853960, 3856753, 856171, 856381
• Crusader 12370

Frequently Asked Questions

What engines does the Sierra 18-3937 piston ring set fit? The Sierra 18-3937 fits the 8.9L 575 marine V8 engine family (540 cid, 8-cylinder) covering the 1986-1992 range.

Is the Sierra 18-3937 a direct replacement for my OEM piston rings? Yes, 18-3937 cross-references directly to GM 14089025, Mercury Marine 39-17464, Mercruiser part numbers, OMC part numbers, and Volvo Penta part numbers used on the same 8.9L 575 engine family, so it installs as a direct OEM replacement.

What size is the Sierra 18-3937 piston ring set? 18-3937 is the standard (STD) size set; related Sierra part numbers 18-3939 and 18-3938 cover other sizes for the same engine family, so confirm the size stamped on your original pistons before ordering.

What is included with the 18-3937 piston ring set? Each 18-3937 set is supplied complete with the piston rings and wrist pin, sold individually as one set per connecting rod.

What material are the Sierra 18-3937 piston rings made from? The 18-3937 uses forged aluminum piston construction with a recessed head design, built for the load and heat cycling of a marine inboard/sterndrive V8.

How much does the Sierra 18-3937 piston ring set weigh? The 18-3937 piston ring set weighs 0.15 pounds.

Does the Sierra 18-3937 meet OEM performance standards? Sierra manufactures the 18-3937 to meet or exceed the original equipment piston ring part it replaces.

Which brands used the engine that the 18-3937 fits? The 8.9L 575 engine platform that the 18-3937 fits was serviced under Mercruiser, OMC, and Volvo Penta part numbering, which is why 18-3937 cross-references to part numbers from all three.

What is the difference between Sierra 18-3937, 18-3939, and 18-3938? 18-3937 is the standard-size piston ring set for the 8.9L 575 engine family; 18-3939 and 18-3938 are separate Sierra part numbers covering other sizes in the same engine application, so the correct one depends on the size of your original pistons.

Can I install the 18-3937 piston rings myself? The 18-3937 set comes complete with rings and a wrist pin for a full piston rebuild, though fitting piston rings requires engine teardown and should follow the engine manufacturer's ring gap and installation procedure.

Is the Sierra 18-3937 genuine or aftermarket? 18-3937 is a Sierra-branded aftermarket piston ring set engineered to meet or exceed OEM specifications for the 8.9L 575 engine family, rather than a part sold under the original engine brand's own packaging.