Crush washers

[All U Get]

Hi all,

We had a little fuel leak on the fuel line to the injector on our diesel generator and I had narrowed it down to the banjo fitting. I tried to just tighten it, but the leak continued so we ordered some new crush washers to replace the old. I could only get my hand in a narrow area to work on the line and at first couldn't get a good seal. By backing it out slightly and then tightening I was able to reduce it to a few drops a minute.

Since it got a little cool I decided to secure a funnel and bottle to catch the drips while we ran the generator. After repeating to tightening sequence a few more times over several days I have reduced it enough to remove the bottle and after a two hour run, wipe any drips with a paper towel. Success almost.

All U Get

 

[Rich Stidger]

If you have a washer leak and you don't have a new crush washer in your spares kit, you may be able to anneal the old copper washer and re-use it. To do this you need to heat the washer to cherry red and then immediately drop it into cold water. This will remove the hardness of the copper and change its properties to dead soft.

Now when you replace the washer it will crush again and seal the fitting.

I have personally used this technique on sealing washers for an Oldsmobile diesel engine with positive results. Obviously I can't guarantee that this method will always work so YMMV.

 

[All U Get]

Thanks Rich, good to know. I got a torque wrench and was able to get another 1/6th of a turn and it is dry after two hours of running.

All U Get

 

[rgranger]

... To do this you need to heat the washer to cherry red and then immediately drop it into cold water. This will remove the hardness of the copper and change its properties to dead soft.

...

Full Disclosure! I've never done this and I'm not a metallurgist ... but I do teach a section on metallurgy in one of my classes. From what I know from books, Rich is exactly correct. Copper is purported to be easily work hardened. Heating it to red hot will move it through several solid phase transitions and from a molecular perspective it will have an amorphous (glass like) structure at "red hot". Cooling it rapidly keeps the crystalline state from reforming (molecular motion is retarded before the crystalline state has time to form).

If you give it a try, I'd love to hear how it worked.

 

[Chris Patterson]

Scuff the washers flat before hand helps. Lay a sheet of around 400 paper on something very flat and scuff them good. A flat sealing surface to begin with takes some of the reformation out of the problem. To keep tightening and loosening is doing the same and opposite deformation as the heating, ie: sorta making it worse. These things can be heated that way simply by hanging the washer on a stainless wire or bolt heated with propane, and quickly dropping it into water. Oil makes it even harder. Maybe TOO hard, the experts in metallurgy will know better than I..