Sierra Magnetic Drain Screw 18-2378, Replaces 309243, for Cobra Drives & V-6 40-50HP (1989-97)

The Sierra 18-2378 is a magnetic drain screw designed for gearcase drain and fill service on Cobra Drives & V-6 applications, 40-50HP (1989-97). The built-in magnetic tip attracts fine metal particles circulating in the gear lubricant, helping catch early signs of internal wear before they cause bigger gearcase problems. It is a direct replacement for OEM number 309243, so it installs in the original drain location without modification.

This drain screw is supplied in a package of 50, without washer, making it a practical choice for shops and technicians who service multiple units or want spares on hand for routine gearcase maintenance and lubricant changes. Keeping the drain screw magnetic and in good condition is a simple, low-cost way to monitor gearcase health during scheduled service intervals.

Specifications

• Brand: Sierra
• Manufacturer Part Number: 18-2378
• Product Type: Magnetic Drain Screw
• OEM Cross Reference: 309243
• Fitment: Cobra Drives & V-6, 40-50HP (1989-97)
• Package Quantity: 50 (without washer)
• Weight: 0.03 pounds
• UPC: 808282257811

Fitment

• Cobra Drives & V-6, 40-50HP (1989-97)

Replaces (OEM)

• 309243

Frequently Asked Questions

What is the Sierra 18-2378 used for? The Sierra 18-2378 is a magnetic drain screw used in the gearcase drain and fill port to service gear lubricant on Cobra Drives & V-6 applications, 40-50HP (1989-97).

Does the 18-2378 replace OEM part 309243? Yes, Sierra part 18-2378 is a direct replacement for OEM number 309243.

What does 'magnetic' mean on this drain screw? The tip of the 18-2378 drain screw is magnetized so it attracts fine metal particles suspended in the gear lubricant, giving a visual early indicator of internal wear when the screw is removed during service.

Which engines and horsepower range does 18-2378 fit? This drain screw fits Cobra Drives & V-6 applications rated 40-50HP (1989-97).

Does the 18-2378 come with a washer? No, the 18-2378 package is supplied without a washer.

How many drain screws come in a package of the 18-2378? The 18-2378 is packaged in a quantity of 50 per package.

How much does the 18-2378 magnetic drain screw weigh? The Sierra 18-2378 weighs 0.03 pounds.

Is the 18-2378 a genuine Sierra part? Yes, 18-2378 is Sierra's own part number for this magnetic drain screw.

Can the 18-2378 be used for both drain and fill service? Yes, the 18-2378 magnetic drain screw is used at the gearcase drain location during lubricant drain and fill service.

What is the UPC for the Sierra 18-2378? The UPC for the Sierra 18-2378 magnetic drain screw is 808282257811.