This is Atlas Copco part number 1638903680, also listed as 9234000638 fuel tank cap, stocked at Crowder Supply as AC-1638903680. It closes a port or passage in the tool. Small, but a plug that will not seal turns into a leak that is hard to trace.

Give us the model and serial off your machine and we will confirm the fit; the parts breakdown index and the Atlas Copco lineup are the other two places to start. It ships out of Denver, same day on in-stock orders placed before 4 PM ET.

• Part number: 1638903680
• Also listed as: 9234000638
• Manufacturer: Atlas Copco
• Crowder SKU: AC-1638903680