Yamaha - Oil Tank Cap Assembly - Oil System - 6E5-21770-03-00

Overview

This is one of those parts you don’t think about until it starts causing a mess or letting air into the system. A good oil tank cap needs to seal tight and keep everything where it belongs, especially on 2-stroke setups where oil flow matters. I’ve seen cracked or loose caps lead to leaks and even affect how oil feeds into the motor. Swapping it out is a simple fix that keeps your oil system clean and working the way it should.

Key Features

• Secure Sealing Design – Keeps the oil tank properly sealed to prevent leaks and contamination.
• Integrated Vent Function – Allows proper airflow to support consistent oil delivery.
• Durable Construction – Built to handle vibration, exposure, and long-term marine use.
• OEM Fitment – Threads and seals correctly with Yamaha oil tanks for reliable installation.

Engine & Boat Compatibility

Designed for Yamaha 2-stroke outboard engines with remote or onboard oil tank systems. Commonly used on mid-range and smaller horsepower motors found on fishing boats, skiffs, and utility vessels.

FAQ

Q: What are signs of a bad oil tank cap?
A: Oil leaks, loose fitment, or difficulty maintaining proper oil flow can point to a worn cap.

Q: Can this affect how oil feeds into the engine?
A: Yes, if the cap doesn’t vent or seal properly, it can disrupt oil delivery.

Q: Is this part easy to replace?
A: Very easy—just remove the old cap and thread the new one on securely.

Q: Does saltwater exposure damage the cap?
A: Over time, yes—sun and salt can cause cracking or weakening of the material.

Q: Should I check this during regular maintenance?
A: It’s a good idea to inspect it occasionally for cracks or worn seals.