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The Sierra 18-3921 is a standard bore piston ring set engineered as a direct replacement for Mercury Marine outboard engines. Designed to meet or exceed original equipment specifications, this ring set is a trusted aftermarket solution for engine rebuilds and top-end overhauls on compatible Mercury and Mariner V6 2.0L outboards.
This set directly replaces Mercury Marine OEM part number 39-93481A12 (also cross-referenced as 39-78918A4 and 39-85636A4), as well as Mallory 9-54233, GLM 14240, and Wiseco 3125KD. The rings feature a standard bore diameter of 3.125 inches and are sold as a pair — two rings per piston — making them ideal for single-cylinder replacement or full engine re-ring projects when ordered in the appropriate quantity.
Key Features:
Sierra International is a premier manufacturer of marine engine replacement parts, with a long-standing reputation for quality and reliability in the marine aftermarket. The 18-3921 piston ring set is a cost-effective solution for restoring proper compression and engine performance during maintenance or rebuild of compatible Mercury Marine powerheads.
Product came just three days after I ordered it! Great product at a great price. I would definitely order from them again!
rwb67c
All good so far
Bradford L. Griffith
I bought shocks for my Silverado. Very little product info given, I had to search part numbers on other websites to verify what shocks were for the front and what ones were for the rear. Also I would very much like to be able to ship to a different addres
Joel Kallgren
Thanks
john decker
Was quick and easy. Hope to get product quickly!
Amanda Knape
Really handy being able to pay through Amazon.
Frederick T. Hormes
execllent store, price was wonderful and product was top quality. shipping is average, it took 2 days to proccess. I will recommend to friends and use again.
sergiorussi
Good experience would definitely buy from again
chad
I have had excellent service from this site and speedy delivery. They also send you an email with order info and tracking number everytime.
Fowler308
Great prices and prompt shipping
alflessel
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