Yamaha - Oil Tank Cap Assembly - Lubrication System Component - 6H4-21770-00-00

Overview

It’s easy to overlook something like an oil tank cap until it starts causing problems. I’ve seen loose or worn caps let air or moisture into the system, and that’s not something you want anywhere near your oil supply. This piece helps keep everything sealed and working the way it should. When it’s doing its job, you don’t think about it—but when it’s not, it can lead to bigger issues.

Key Features

• Secure Tank Seal – Helps maintain a tight seal to protect the oil supply from contamination.
• Proper Venting Function – Supports correct airflow to allow consistent oil delivery.
• OEM Fitment Design – Built to Yamaha specifications for reliable fit and sealing.
• Durable Cap Construction – Designed to handle heat, vibration, and marine exposure.
• Supports System Integrity – Helps ensure the oil injection system operates without interruption.

Engine & Boat Compatibility

Designed for Yamaha outboards equipped with compatible oil injection systems. Commonly used across small to mid-size two-stroke engines found on fishing boats, skiffs, and recreational vessels. Always verify compatibility with your specific engine before installation.

FAQ

Q: What are signs the oil tank cap needs replacing?
A: Loose fit, visible cracks, or oil residue around the cap are common signs.

Q: Can a bad cap affect engine performance?
A: Yes, if air or contaminants enter the system, it can disrupt proper oil delivery.

Q: Does this cap need to be tightened a certain way?
A: Just snug and secure—over-tightening isn’t necessary and can cause wear over time.

Q: Can saltwater exposure damage the cap?
A: Over time, yes—constant exposure can lead to wear or degradation of the sealing surfaces.

Q: Should I replace this during routine maintenance?
A: It’s a good idea to inspect it regularly and replace it if there are any signs of wear.

• Supersessions
  6H4-21770-01-00, 6H4-21770-01-00