Nige
Senior Member
Have you replaced the breaker relief valve on the tank yet..?
Yes but no change the breather I got was 507-0646 cat# it didn’t have the push down to relief the air. But it had the same nipple to screw down on the tank. Parts book show a screen on the inside of the tank where the return line from the filter goes through the tank. Not sure if that screen could be plugged? Haven’t put a gauge on the sending unit either.
Wish I could see that pressure switch/Sender. Not sure if it is a differential pressure switch like say the 988H transmission filter we had at work or if it is just a straight pressure switch. Kind of sounds like a straight pressure switch because of the way the schematic refers to the open/close pressure and does not have the word "differential" in the specification. But then we all know what happens to those who "assume" anything.If that sender is reporting differential pressure across a filter, what difference does a restriction in the tank make? The pressure will just backup and the filter will show the same pressure on both the inlet and outlet ends of the filter housing.
Find a way to put a gauge in both sides of the filter to see what you actually have and troubleshoot from there.
It's a straight pressure switch Ken, #2 in the illustration. It's plumbed into the filter inlet port and when the pressure in the incoming line rises high enough (as it would if the filter was plugged) it sets off the filter change warning.