479956 Manifold Drain Plug Kit for Volvo Penta GM | JLM Marine

Manifold Drain Plug Kit – Fits Volvo Penta GM V6 and V8 Engines

This Manifold Drain Plug Kit is designed for Volvo Penta GM-based V6 and V8 marine engines, including popular models such as 4.3L, 5.0L, 5.7L, 7.4L, and 8.2L. Located on the rear (propeller side) of the manifold, this quick-drain plastic cock simplifies winterization and routine maintenance, making it an essential replacement part for proper engine care.

Direct Replacement for OEM Part Number: Volvo Penta 479956, GLM 13982, Sierra 18-4227, and others. This aftermarket kit delivers reliable performance and fit for Volvo Penta and OMC applications.

• Precise Metric Threading: Outer dimension 20.50mm × 1.75 metric thread; plastic handle 10.70mm diameter with 2.5 metric thread
• Complete Kit: Includes 2 exhaust manifold drain plug assemblies with all components shown
• Quick-Drain Design: Plastic cock design allows for fast, tool-free draining during winterization or service

Part Number Cross-Reference

Use this table to confirm equivalent part numbers across OEM and aftermarket brands.

Compatible Engine Models

Confirm your engine model/year in the table below.

Technical Specifications

Package Contents

This kit includes:

• 2 × Exhaust Manifold Drain Plug Assemblies (complete kits)
• All components shown in the product images

Installation Guide

1. Ensure the engine is completely cool and turned off before beginning work.
2. Locate the existing drain plugs on the rear (propeller side) of each exhaust manifold.
3. If replacing old plugs, carefully unscrew the existing drain plug assembly by turning counterclockwise.
4. Clean the manifold drain port threads thoroughly, removing any debris, corrosion, or old sealant.
5. Apply marine-grade thread sealant to the threads of the new drain plug (20.50mm × 1.75 metric thread).
6. Hand-thread the new drain plug into the manifold port, turning clockwise until finger-tight.
7. Tighten the plug securely using an appropriate wrench—do not over-torque to avoid stripping threads.
8. Ensure the plastic drain cock handle is in the closed position (perpendicular to the manifold).
9. Repeat the process for the second manifold if applicable.
10. Start the engine and inspect both drain plugs for leaks while the engine warms up.
11. If any seepage is detected, shut down the engine and re-tighten slightly. Do not operate with leaking drain plugs.
12. Test the quick-drain function by opening the plastic cock; close immediately and confirm a watertight seal before use.

Troubleshooting & FAQ

Q: How do I confirm this drain plug kit fits my Volvo Penta engine?
A: Verify your engine is a GM-based V6 or V8 model (4.3L, 5.0L, 5.7L, 7.4L, or 8.2L). Check the existing drain plug thread size—it should be 20.50mm × 1.75 metric. Cross-reference your current OEM part number (479956, GLM 13982, Sierra 18-4227, etc.) with the table above.

Q: Will this kit work on OMC engines?
A: Yes, this kit fits OMC 4.3L and 5.7L GM-based engines only. It is not compatible with OMC Ford or Chrysler-based blocks. Confirm your OMC engine uses GM architecture before ordering.

Q: How often should I replace the manifold drain plugs?
A: Inspect drain plugs annually during winterization or routine service. Replace immediately if you notice cracking in the plastic handle, thread wear, leaks, or difficulty opening/closing the drain cock. Exposure to saltwater or harsh conditions may shorten service life.

Q: Why is my drain plug leaking after installation?
A: Leaks are typically caused by insufficient thread sealant, cross-threading during installation, or damaged manifold threads. Remove the plug, inspect threads on both the plug and manifold, reapply marine sealant, and reinstall carefully by hand first to avoid cross-threading.

Q: Can I leave the drain cock open during storage?
A: Yes, leaving the drain cock open during off-season storage is recommended to allow complete water drainage and prevent freeze damage. Just remember to close it securely before launching in the spring.

Q: What's the difference between OEM and aftermarket drain plug kits?
A: This listing is an aftermarket replacement part (not an OEM component). We build to OEM specifications using comparable-grade materials. Production is done in an ISO9002-certified facility, and each batch is inspected for consistent performance.

Q: How fast do you ship and how much does it cost?
A: We offer fast global shipping—typically 5–15 days worldwide—and standard shipping is free. Expedited options are available at checkout depending on your location.

Q: What is your warranty and return policy?
A: This product includes a 1-year warranty against manufacturing defects under normal use. If something goes wrong, contact our support team with your order details. Returns are accepted within our standard return window (unused & in original condition); please see our policy page or reach out for instructions.

Important Notes

• Verify that the product images and specifications match your original part. If discrepancies exist—even if your model is listed—do not proceed with the purchase.
• This product is an aftermarket replacement part and is not an OEM component.
• Professional installation is recommended to ensure safety and optimal performance.

Why Choose JLM MARINE?

• Quality Assured: As a trusted manufacturer for over 20 years, we supply top marine brands globally.
• Fast Global Shipping: Free delivery worldwide in 5–15 days.
• Direct from Manufacturer: Competitive pricing without compromising quality.