Oil Breather Cap

When I got to the oil breather caps, there were a couple of things to do.  First, both needed the stainless steel scouring pad inserts.  I had previously put these on the 330 caps, so already had everything.

The second item was that the screen on one of the caps had been broken off.  I measured the mesh and came up with about 25 hole per inch.  I would have thought that the screening material would have been brass, but a magnet showed it to be steel, so ordered a piece of zinc plated steel screening that had 24 holes per inch from McMaster-Carr.  You can't buy steel screening at a hardware store anymore.  All they sell is either plastic or aluminum.

The whole cap is aluminum except there is a steel ring inserted in the middle to solder the screening to.  This ring is staked into the aluminum cap and I decided to not try and remove it, though that would have made the soldering easier.  Instead, I used a propane torch to heat the ring enough to remove the remnants of the old screen, cleaned off the old solder and re-tinned that area.

Then I cut out a triangle of screening to make into the cone.  It took a couple of passes before I got the right dimensions so the cone looked good and fit into the steel ring.  I practiced soldering one edge on one of these early pieces.

Then I rolled it into a cone using a wide bladed vise grip pliers designed for welding.  A little adjusting got it to fit into the ring properly.  Then I tinned the bottom edge of the cone and re-heated the ring.  Once the solder in the ring was liquid again, I placed the cone into the ring and let it cool a bit, just until the solder hardened.  Then using a soldering iron, I added solder as needed to fill the gap between the base of the cone and the ring.  After everything had cooled, I then soldered up the joint to the tip of the cone.  Here's the one with the original cone intact and the one I just fixed.

The last thing to do is decide how to finish the exposed surface of the cap.  These are not supposed to be shiny, but since these were glass beaded, they are a bit dull.  Maybe just some hand work with some fine steel wool will add a little shine without being gaudy.

George stopped by and brought over his breather caps to get new screening.  The process for his was the same as mine except that the screens under the perforated plates were missing or badly rusted in his.  So we replaced those too.  After cutting to size, I rolled each around a 19mm long socket to make them tighter than the diameter in the cap area.  Then it was just a matter of holding the overlapping ends tight as I soldered the two layers together.

The other thing we did was to clean up the perforated plates and retaining rings.  Then I blackened them.  Not that anybody can see that area unless the cap is removed, but it does finish them off nicely.