Aluminum Crush Washers: Reuse or Replace Each Time
By DeatschWerks | Published: 2026-10-18
Category: Tips & Care
Learn why aluminum crush washers are single-use and should be replaced every time you loosen an AN fitting. Avoid leaks with fresh washers.
Quick answer
Replace aluminum crush washers every time you loosen an AN fitting. They are designed to deform for a leak-free seal and lose that ability after one use.
Why the myth persists
Some enthusiasts reuse crush washers because they look fine or because copper washers can sometimes be annealed and reused. Aluminum crush washers work differently: they permanently deform under torque to create a seal. Once compressed, they cannot reliably seal again.
Reusing an aluminum crush washer risks a slow leak that may go unnoticed until it causes a pressure drop or contamination in your fuel system. The cost of a fresh washer is far lower than the cost of diagnosing a leak.
What about AN fittings with integrated seals?
Some AN fittings use O-rings instead of crush washers. If your fitting has an O-ring groove, follow the manufacturer's instructions for that seal type. Crush washers are used specifically where the fitting requires a deformable washer to seal against a flat surface.
The verdicts
- Claim: Aluminum crush washers can be reused if they look undamaged: Verdict: False. Aluminum crush washers are designed to deform permanently under torque to create a leak-free seal. After one compression, the material has already yielded and cannot reliably seal a second time. Always install a new crush washer when reassembling any AN fitting that uses one.
- Claim: Reusing a crush washer saves money: Verdict: Misleading. A single washer costs pennies, while a fuel leak can damage components or cause a fire. The small upfront cost of replacement is negligible compared to the potential repair bill. Buy a multi-pack so you always have spares; the per-washer cost drops significantly.
- Claim: All crush washers are the same: Verdict: False. Crush washers come in different materials (aluminum, copper, steel) and sizes (4AN, 6AN, 8AN, 10AN, 12AN, etc.). Using the wrong size or material can lead to leaks or fitting damage. Match the washer size exactly to your AN fitting size. DeatschWerks offers packs for common sizes like 4AN, 10AN, and 12AN.
Products that make replacement easy
- 4AN Aluminum Crush Washer (Pack Of 10): Pack of 10 aluminum crush washers for 4AN fittings, made from aluminum for corrosion resistance and consistent sealing. Having a pack on hand means you always have a fresh washer ready, so there is no temptation to reuse an old one.
4AN Aluminum Crush Washer (Pack Of 10) - 10AN Aluminum Crush Washer (Pack Of 10): Pack of 10 aluminum crush washers for 10AN fittings, designed to create a secure seal in fuel or oil system connections. If your build uses 10AN fittings, this pack gives you enough washers for multiple service intervals without needing to hunt for singles.
10AN Aluminum Crush Washer (Pack Of 10) - 12AN Aluminum Crush Washer (Pack Of 10): Pack of 10 aluminum crush washers for 12AN fittings, providing a reliable sealing solution for clamping and sealing applications. Larger AN sizes still require fresh washers each time; this pack ensures you have the correct size ready when you service the system.
