Porter-Cable 904689 Head Valve Seal – Genuine OEM Replacement Pneumatic Nailer Head Valve Seal
Part Number: 904689
Category: Pneumatic Nailer Parts → Head Valve Components → Head Valve Seals
Type: Porter-Cable 904689 Head Valve Seal – Genuine OEM Replacement Pneumatic Nailer Head Valve Seal
The Porter-Cable 904689 Head Valve Seal is a genuine OEM replacement seal designed for compatible Porter-Cable pneumatic finish nailers. Installed at the top of the cylinder beneath the head cap, this seal creates an airtight barrier for the head valve, allowing the nailer to cycle properly and maintain consistent air pressure. Manufactured to original equipment specifications, it provides a direct-fit replacement for worn, damaged, or leaking seals, helping restore reliable firing performance and reduce air leaks. Because head valve seals compress during installation, they should be replaced whenever removed to ensure a proper seal.
Key Features & Benefits
- Part Number: 904689
- Genuine OEM Porter-Cable replacement part
- Replacement head valve seal for compatible pneumatic nailers
- Creates an airtight seal between the head valve and cylinder
- Helps eliminate air leaks from the top of the tool
- Durable sealing material designed for pneumatic applications
- Direct-fit OEM replacement
- Manufactured to original equipment specifications
Technical Specifications
Part Number: 904689
Manufacturer: Porter-Cable / Stanley Black & Decker
Product Type: Head Valve Seal
Material: Pneumatic-grade sealing material
Application: Pneumatic Finish Nailer Head Valve
OEM Part: Yes
Quantity: Sold Individually
Compatible Applications
The Porter-Cable 904689 Head Valve Seal fits compatible Porter-Cable finish nailers, including:
Porter-Cable
- FN250B Type 1
- FN251 Type 1
Always verify your nailer model, type number, and original part number before ordering to ensure proper compatibility.
Function of the Head Valve Seal
The 904689 Head Valve Seal is designed to:
- Create an airtight seal for the head valve
- Maintain proper air pressure during firing
- Prevent air leakage from the top cap
- Support consistent nail driving performance
- Improve overall pneumatic efficiency
- Restore the factory head valve sealing system
Common Signs Replacement Is Needed
Replace the head valve seal if you notice:
- Air leaking from the top of the nailer
- Reduced driving power
- Inconsistent firing or cycling
- Worn, cracked, or flattened seal
- Air escaping after the trigger is released
- Seal damaged during disassembly
A damaged head valve seal can prevent the nailer from maintaining proper air pressure, resulting in poor performance and continuous air leaks.
Installation & Service Notes
Disconnect the nailer from the air supply and remove all fasteners before performing any maintenance.
Remove the top cap to access the head valve assembly. Carefully remove the worn 904689 Head Valve Seal, clean the sealing surfaces, and inspect the head valve and cylinder for damage or debris. Install the new seal in the correct orientation, reassemble the head cap, and tighten the fasteners evenly according to the manufacturer's specifications. Reconnect the air supply and verify proper operation while checking for air leaks. If additional internal seals show signs of wear, consider installing the compatible 904949 Overhaul Kit during service.
Important: Head valve seals are intended for one-time installation. If the seal has been removed during servicing, replace it with a new OEM seal to maintain a reliable airtight connection.
Maintenance Recommendations
- Add pneumatic tool oil before each day of use unless your tool specifies otherwise.
- Inspect the head valve area periodically for air leaks.
- Replace worn seals promptly to maintain proper firing performance.
- Keep the head assembly clean during servicing.
- Rebuild aging nailers with OEM seal kits as needed.
- Use genuine OEM replacement parts to maintain factory fit, proper sealing, and long-term pneumatic nailer performance.
