Originally Posted by poboyengineering
I was going to post this same question about the sponge.
Since not all pumps have it, is there a downside or advantage to leaving it out?
all carter 3 valve pumps i've messed with have the sponge. i take my pumps apart and re-work them and don't put the sponge back in with no adverse effects. i say keep it if you want, remove it if you don't; hasn't made any issues one way or the other for me.