Easy
15-30 minutes
This is an authentic part from Porter Cable. This piston ring is to be used in Porter Cable Finish Nailers. The piston ring is installed next to the o-ring and prevents air from leaking out of the device. This item is sold as an individual part. Replacing this part may require a screwdriver and an Allen wrench.
Piston Ring 904691
OEM part for: Porter Cable
Part Number: 904691
$11.00
In Stock
Ships within 1 business day 
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Frequently Purchased Together ?
Compatibility
This part will fit the following 3 machines
Porter Cable
FN250B 16 Gauge Finish Nailer View Diagrams & Manuals
FN251 (Type 1) Flooring Nailer View Diagrams & Manuals
FN250B (Type 1) Finish Nailer Power Tool View Diagrams & Manuals
This item works with the following types of products:
- Nailer Parts
Customer Part Reviews ?
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Easy repair, worked as expected
Finishing nail gun works great
Guest -
July 28, 2023
Verified Purchase
Part was delivered in a timely manner and worked perfectly.
worked great
Guest -
October 13, 2020
Verified Purchase
Nail gun repaired.
Parts arrived quickly and worked as expected.
John -
April 22, 2020
Verified Purchase
EXCELLENT SERVICE!!
Correct part shipped when promised.
Guest -
September 4, 2019
Verified Purchase
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Verified Purchase
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Questions & Answers ?
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Does this fit my product?Questions & Answers for Piston Ring
Is the piston ring a split ring?
Chuck
for model number fn250B
asked on 2022-07-19
Hi Chuck,
Thank you for your question. Yes, this would be a split ring. If you need help placing an order for it, customer service is open 7 days a week and anyone will be happy to assist you. Please feel free to give us a call. We look forward to hearing from you!
eReplacementParts Team July 19, 2022
Customer Repair Instructions ?
All our customer repair instructions are solicited directly from other customers just like you who have purchased and replaced this exact part.
Internal parts broke
Tim - June 18, 2022
Tool Type
Stapler
Difficulty
Easy
Time
Less than 15 minutes
Tools Used
Screwdriver
Took the nailer all apart and got on ereplacement found the parts needed, ordered them and had them in 3 days and replaced the bad parts and the stapler works like new now.
Everything went smooth from finding the parts, too ordering the parts, to shipping and assembling the parts. Will use this company again and highly recommend them
Everything went smooth from finding the parts, too ordering the parts, to shipping and assembling the parts. Will use this company again and highly recommend them
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Nailer: broken cylinder.
Gary - February 22, 2019
Tool Type
Nailer
Difficulty
Easy
Time
15-30 minutes
Tools Used
Pliers, Allen
Removed all of the internal parts. Salvaged usable gaskets and rings. Checked everything for wear and then replaced the cylinder in the casing. Put the cover back in place and I was back in business.
The parts were exactly what I needed.
By the way, thank you YouTube.
The parts were exactly what I needed.
By the way, thank you YouTube.
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Leaking air
warren - October 4, 2017
Tool Type
Nailer
Difficulty
Easy
Time
15-30 minutes
Tools Used
, Allen wrench
Unscrewed the four screws from the cap
Removed the old piston ring and o-ring
Installed new the o-ring and piston ring
Cleaned and oiled the inside parts
Replaced the cap
Removed the old piston ring and o-ring
Installed new the o-ring and piston ring
Cleaned and oiled the inside parts
Replaced the cap
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Air leak in piston compression/stop head assembly
Mike - July 1, 2016
Tool Type
Nailer
Difficulty
Easy
Time
30-60 minutes
Tools Used
Screwdriver, Pliers, Allen wrench
1. Removed hex bolts from head
2. Dissembled piston stop and compression assembly
3. Laid all components in order on work bench
4. Utilized individual parts breakdown diagram to validate component assembly
5. Removed and replaced damaged and worn parts
6. Re-assembled components in correct order
7. Installed head hex bolts
8. Oiled and tested tool
9. No air leaks
10. Tool is back in service
2. Dissembled piston stop and compression assembly
3. Laid all components in order on work bench
4. Utilized individual parts breakdown diagram to validate component assembly
5. Removed and replaced damaged and worn parts
6. Re-assembled components in correct order
7. Installed head hex bolts
8. Oiled and tested tool
9. No air leaks
10. Tool is back in service
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Seal was bad and air was excaping
Dany - December 26, 2016
👍 0 of 1 people found this instruction helpful
Tool Type
Stapler
Difficulty
Easy
Time
30-60 minutes
Tools Used
Wrench Set
Pulled the top of the stapler gun, replaced the seal and completed the assembly.
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Finish nailer had no force to drive a nail.
Bob - July 27, 2016
👍 0 of 1 people found this instruction helpful
Tool Type
Nailer
Difficulty
Easy
Time
15-30 minutes
Tools Used
Screwdriver, Allen wrench
Parts Used
Remove the end cap and took out bumper. Popped the cylinder out by tapping the nailer body against a 2x4. Took the piston and driver out along with the guide. Installed new piston ring and lubricated with silicone grease. Reassembled in reverse order.
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Our customer service team are at the ready daily to answer your part and product questions. We have a dedicated staff with decades of collective experience in helping customers just like you purchase parts to repair their products.
All our part reviews are solicited directly from other customers who have purchased this exact part. While we moderate these reviews for profanity, offensive language or personally identifiable information, these reviews are posted exactly as submitted and no alterations are made by our team.
All our customer repair instructions are solicited directly from other customers just like you who have purchased and replaced this exact part. While we moderate these reviews for profanity, offensive language or personally identifiable information, these reviews are posted exactly as submitted and no alterations are made by our team.
Based on data from past customer purchasing behaviors, these parts are most commonly purchased together along with the part you are viewing. These parts may be necessary or helpful to replace to complete your current repair.
All our installation videos are created and produced in collaboration with our in-house repair technician, Mark Sodja, who has helped millions of eReplacementParts customers over the last 13 years repair their products. Mark has years of experience in selling and repairing both commercial and residential products with a specialty in gas-powered equipment.
This data is collected from customers who submitted a repair instruction after replacing this exact part. Customers can rate how easy the repair was to complete and how long it took. We aggregate this data to provide a repair rating that allows customers to quickly determine the difficulty and time needed to perform their own repair.
