Take the 2-minute tour ×
Motor Vehicle Maintenance & Repair Stack Exchange is a question and answer site for mechanics and DIY enthusiast owners of cars, trucks, and motorcycles. It's 100% free, no registration required.
  1. Why are copper washers required on banjo fittings?
  2. Why do they need to be replaced each time you remove/loosen the banjo fitting?

I'm assuming that copper is a softer metal than bronze, brass or steel so they will squish when torqued to make a seal. However, I've seen copper crush washers that had an embossed ring in the center of the washer that would actually crush down when under pressure. Today I had to replace the washers for an oil feed line for a turbo but the manual calls for copper washers and not crush washers. Do the flat copper washers work in the same way?

share|improve this question

1 Answer 1

up vote 5 down vote accepted

You are correct that the copper washer is required to create a seal.

Even flat copper washers will deform during tightening to create a seal. They're made from annealed copper, which is very soft. The raised ridge just reduces the load required to initiate the seal.

Generally, these washers should be replaced rather than re-used, as the act of deforming an annealed copper washer effectively "hardens" the material, making it more difficult to crush next time, therefore you may not get a good seal when re-using a copper washer.

share|improve this answer
    
The is a great answer. Regardless of the the topic of the question. It's straight to the point, contains facts, no bs. +1 –  cinelli Mar 26 '13 at 19:19

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.