The pressure valve leaks a little at first as the o-ring that seals the pin shaft shrinks and later it leaks rapidly because the 4mm / 2.5mm stepped diameter nylon pin that carries the force from the spring to the conical fluoropolymer valve tip is chemically unstable in hot water so when the o-ring pin shaft seal ages the pin disintegrates.
The valve is simple to dis-assemble. You must have already opened the case to be able to see that this is the source of the leak. Remove the locking clip that holds the 2 tube manifold to the and separate the manifold from the valve. Remove the screw holding the valve and it’s mounting button. The button will fall onto the brew drive train or into the collecting tray. The valve has another clip holding the pump inlet tube.
The valve’s dome covers the spring, remove the dome carefully, to decompress the spring so it doesn’t fly away. There white post goes down through an insert in the valve body. Remove the post and insert carefully. If the post has disintegrated the end will remain in the conical. It’s fairly simple to turn a replacement from a 1-1/2 in long 1/4-20 stainless machine screw in an electric drill using a file. Remove the screw head, turn the 1” projecting from the chuck to 4mm diameter, turn 12.65mm of the free end to 2.25mm diameter, begin by using a triangular file to cut a square shoulder for the spring before turning the rest, use the triangle file to cut a 0.5mm deep groove (3mm dia) in the 4mm dia 1cm from the shoulder. Turn a rounded shoulder and cut to a flat face for the pin 3mm from the groove. It sounds harder than it is, but you need a digital (or dial) caliper to measure, an electric drill, some small files, and some patience. Buy a few screws, the 1st one isn’t likely to turn out well. If you have an “air die grinder” use that instead of a drill. If you have to buy files, buy an 8” or 10” “mill bastard” for turning flat areas, and a $5 set of miniature files for the triangular file and a mini flat file to smooth with. A piece of 400 grit silicon carbide sandpaper is good for final smoothing.
close
Share this post: