Sierra Timing Cover Seal 18-1213, Replaces 26-11973, Fits I/L-6, V-6 4.3L, V-8 5.0L/5.7L Marine Engines

The Sierra 18-1213 is a timing cover seal engineered for marine sterndrive and inboard engines, sealing the timing cover against oil leakage where the front cover meets the engine block. It is built as a one-piece seal for standard rotation applications across a range of GM-based marine engine blocks, including 3.0L, 4.3L V-6, and 5.0L/5.7L V-8 configurations, as well as inline six-cylinder engines. Because oil seals harden and shrink with age and heat cycling, the 18-1213 is a common preventive-maintenance and leak-repair replacement during timing cover service, front seal replacement, or engine rebuilds.

Fitment for the 18-1213 is tied to specific engine serial number breaks rather than a single universal application, so it covers 140/3.0L and LX engines from serial number 6229718 and up, 150/160/165/200 inline six-cylinder engines from serial number 1666495 and up (and again from 2770032 and up), 175/185/205/262/4.3L V-6 engines from serial number 6330183 and up, and 200 through 320 horsepower 5.0L/5.7L/898 V-8 engines from serial number 2453769 and up. It is also listed as the one-piece seal for standard-rotation 5.0L/5.7L, 4.3L, and 3.0L applications. On several of these engine ranges, the 18-1213 is used alongside a companion seal, part number 18-1211, as part of the same timing cover service -- confirm your engine's serial number range to determine whether both seals are needed for your application.

Specifications

• Brand: Sierra
• Manufacturer Part Number: 18-1213
• Product Type: Timing Cover Seal
• Seal Configuration: One-piece seal, standard rotation
• OEM Cross Reference: 26-11973
• UPC: 808282242916
• Weight: 0.05 pounds
• Product Dimensions: 0.39 x 0.39 x 0.39 inches

Fitment

• 140/3.0L & LX: engine serial number 6229718 and up
• 150/160/165/200 (I/L-6): engine serial number 1666495 and up
• 150/160/165/200 (I/L-6): engine serial number 2770032 and up
• 175/185/205/262/4.3L (V-6): engine serial number 6330183 and up
• 200/228/225/230/250/255/260/270/280/300/320/5.0L/5.7L/898 (V-8): engine serial number 2453769 and up
• 5.0L/5.7L, 4.3L, 3.0L standard rotation, all, one-piece seal application

Replaces (OEM)

• 26-11973

Frequently Asked Questions

What is the Sierra 18-1213 used for? The Sierra 18-1213 is a timing cover seal that seals the timing cover against oil leaks on marine sterndrive and inboard engines, and is typically replaced during timing cover service or when an engine develops a front oil leak.

What engines does the 18-1213 timing cover seal fit? It fits 140/3.0L and LX engines from serial number 6229718 and up, 150/160/165/200 inline six-cylinder engines from serial number 1666495 and up (and from 2770032 and up), 175/185/205/262/4.3L V-6 engines from serial number 6330183 and up, and 200 through 320 horsepower 5.0L/5.7L/898 V-8 engines from serial number 2453769 and up.

How do I know if the 18-1213 is the correct seal for my engine, or if I need 18-1211 too? Fitment for the 18-1213 depends on your engine's serial number range; on several of the listed engine ranges it is used together with a companion seal, part number 18-1211, as part of the same timing cover job, so check your engine's serial number to confirm whether both are required.

Is the Sierra 18-1213 the same as OEM part 26-11973? The Sierra 18-1213 cross-references to OEM part number 26-11973, making it a direct aftermarket equivalent for that application.

What are the dimensions of the 18-1213 seal? The 18-1213 timing cover seal measures 0.39 x 0.39 x 0.39 inches.

How much does the 18-1213 timing cover seal weigh? It weighs 0.05 pounds.

Is the 18-1213 a one-piece or two-piece seal? For standard-rotation 5.0L/5.7L, 4.3L, and 3.0L applications, the 18-1213 is specified as a one-piece seal, simplifying installation compared to split-seal designs.

Does the 18-1213 fit V-6 and V-8 marine engines? Yes, the 18-1213 covers 175/185/205/262/4.3L V-6 engines from serial number 6330183 and up, as well as 200 through 320 horsepower 5.0L/5.7L/898 V-8 engines from serial number 2453769 and up.

What is included when I order the 18-1213? Ordering the 18-1213 provides one timing cover seal, part number 18-1213, for the engine serial number range and configuration that matches your application.

Is the Sierra 18-1213 genuine Sierra or a generic aftermarket part? The 18-1213 is a genuine Sierra part, identified by manufacturer part number 18-1213, and cross-references directly to OEM part 26-11973.

Why does fitment for the 18-1213 depend on engine serial numbers instead of model year? Timing cover seal changes on these marine engines were made at specific production points identified by engine serial number rather than by model year, so the 18-1213's coverage is defined by serial number breaks such as 6229718 and up or 2453769 and up.