Part Location Diagram of 904685 DeWALT PISTON STOP
See part 107 in the diagram
( Grid squares measure 1x1 inch )

PISTON STOP 904685

Manufactured by:
DeWALT
ERP Number:
ERP18987979
Part Number:
904685
Original Equipment Manufacturer ?
  Works with your model  FN251!
In Stock
Delivers in 3-5 Business Days!

Easy 

15 - 30 mins 

(45 rated repairs) ?
  Works with your model   FN251!

Product Description

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This piston stop is for nailers. The piston stop provides a cushion for the piston. Wear work gloves to protect your hands when installing this part.

Frequently Purchased Together

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Troubleshooting

This part works with the following brands:
  • Porter Cable
This part works with the following products:
  • Nailer
Part# 904685 replaces these:
904685,

Customer Part Reviews

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4.9
Average Rating (out of 5):
★★★★★
★★★★★
(11 Reviews)
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Questions & Answers

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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.

Easy 

15 - 30 mins 

(45 rated repairs) ?
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Sorry, we couldn't find any existing installation instruction that matched.

Rebuild head valve

Joseph from Riverview, Florida

20 of 20 people found this instruction helpful.
Difficulty Level:
Easy
Total Repair Time:
15 - 30 mins
Tools:
Pliers, Screw drivers
Parts Used:
904689, 904685
The piston stop had hardened and crumbled. I removed the top of the gun by removing the four hex screws. Then the top of the gun comes off and you can take out the piston stop. I also replaced the head valve seal because it is made out of the same kind of plastic. Pretty easy and now the gun works again.
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Urethane Piston stop crumbled

Cody from Burleson, Texas

18 of 18 people found this instruction helpful.
Difficulty Level:
Easy
Total Repair Time:
15 - 30 mins
Parts Used:
904685, 897359, 890725
Super easy, E replacements online video walked me though it. The repair it showed was different than mine, but the disassembly steps showed me how to take apart the gun in order to diagnose the issue.
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Would not drive nails. Driver rod would not fully retract preventing a new nail from loading

robert from slidell, Louisiana

6 of 6 people found this instruction helpful.
Difficulty Level:
A Bit Difficult
Total Repair Time:
15 - 30 mins
Parts Used:
904685
1. Removed top cover
2 Removed shattered piston stop and cleaned out all of the bits and pieces
3. Reassembled and tested
4..OK
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The gun would not nail and a lot of air came out of the top

Cynthia from Wimberley, Texas

4 of 4 people found this instruction helpful.
Difficulty Level:
A Bit Difficult
Total Repair Time:
15 - 30 mins
Parts Used:
904689, 904685
Removed the cylinder cap from the top of the gun. I then noticed the broken piston stop and loose head seal. I removed all of the pieces of the broken piston stop. and replaced the head seal. Thoroughly cleaned the inside and oiled it. It fires nails like it new.
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Worn out seals and busted piston bumper

Tim from Hoolehua, Hawaii

4 of 4 people found this instruction helpful.
Difficulty Level:
Easy
Total Repair Time:
Less than 15 mins
Parts Used:
904725, 904685, 886119
Follow video that was provided by ereplacement parts and then go from there.
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Leaking air at rop

Mark from OVIEDO, Florida

3 of 3 people found this instruction helpful.
Difficulty Level:
Easy
Total Repair Time:
Less than 15 mins
Tools:
Wrench set
Parts Used:
904685, 890725
Remover allen head screws.
Gently, lifted head from body careful not to damage gasket.
Removed damaged parts and replaced.
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Non-metalic internal parts disintigrated

Michael from Port Orange, Florida

1 person found this instruction helpful.
Difficulty Level:
A Bit Difficult
Total Repair Time:
15 - 30 mins
Parts Used:
904689, 904685
1. Disassembled Nailer
2. Removed debris, residue and broken parts
3. Installed new parts.
4. Applied pressurized air and tested for correct operation.
5. Test failed. Nailer drove one nail, but did not reset. All air pressure lost.
6. Disassembled Nailer again.
7. Installed parts correctly.
8. Reassembled and retested.
9. Nailer worked properly.
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Nailer leaked air and would not fire nails

Michael from GAINESVILLE, Florida

1 person found this instruction helpful.
Difficulty Level:
Easy
Total Repair Time:
15 - 30 mins
Parts Used:
904685
Replaced part (which had totally degraded into several pieces) and put back together (second time correctly). Nailer worked great after that.
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air finish nailer leaking air from top of gun

William from Alexandria, Virginia

1 person found this instruction helpful.
Difficulty Level:
Easy
Total Repair Time:
15 - 30 mins
Tools:
Pliers
Parts Used:
904689, 904685
1) Open top
2) Remove broken / deteriorated parts, replace with new parts. Only hard part was the old piston stop needed needle-nose pliers to pull out.
3) Close top
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Nail gun would not fire nails

Rodney from Richardson, Texas

1 person found this instruction helpful.
Difficulty Level:
A Bit Difficult
Total Repair Time:
15 - 30 mins
Parts Used:
904689, 904685
Removed the screws from the top cover
Removed the defective stop and seal and cleaned the interior of the gun
Installed the new parts
Replace the top cover
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