1841 Dunbier Hydraulic Master Cylinder Cap Suits 1840 | Marine Trailer Part

🔧 Product Description

Dunbier Hydraulic Master-Cylinder Reservoir Cap – Part Number: 1841

A replacement reservoir cap for Dunbier master cylinder 1840. The cap closes the brake-fluid reservoir, supports the venting arrangement and prevents dirt and water entering the hydraulic system.

⚙️ Key Features

• Direct replacement for Dunbier 1840 master cylinder
• Brake-fluid-resistant cap material
• Protects reservoir from contamination
• Maintains the specified venting arrangement
• Service replacement for lost, cracked or damaged cap

📏 Specifications

• Application: Dunbier 1840 / Mackay H3050 master cylinder
• Cap seal or diaphragm is included only as supplied
• Thread or bayonet profile must match the reservoir

🔄 Cross Reference & Related Parts

• Dunbier: 1841
• Master cylinder: Dunbier 1840
• Complete hydraulic coupling assembly: Dunbier 1029 or 1030 where applicable

🚤 Trailer Compatibility & Application

• Suits the Dunbier 1840 master-cylinder reservoir
• Not universal across all trailer master cylinders
• Confirm the old cap profile before replacement

🔌 Function

Seals the brake-fluid reservoir while allowing the designed pressure equalisation as fluid level changes.

⚠️ Common Signs of Failure

• Cap is cracked, swollen or missing
• Brake fluid leaks around the reservoir
• Water or debris is visible in the fluid
• Threads no longer tighten securely
• Vent is blocked and causes brake drag or poor return

🛠️ Installation & Safety

• Clean the reservoir opening before fitting
• Do not allow dirt or water into the brake fluid
• Replace damaged diaphragm or seal components
• Tighten only enough to seal
• Bleed or flush the system if contamination has entered

📦 Condition

• Genuine Dunbier Marine Products trailer component
• Brand new
• Supplied as one replacement master-cylinder cap
• Supplied in original or equivalent packaging