If you have installed the new stainless steel check valve and exhaust
ball in your epoxy pump (to prevent Jeffco hardener discoloration), be
sure to check the ratio when you are through with the installation. We
did and found that the ratio was 7:1 rather than 4:1. Michael
Engineering now says that there is a problem with some of the new
stainless steel check valves - the valve doesn't close completely early
in the upstroke and some of the hardener in the pump body returns to the
reservoir instead of exiting through the exhaust valve - thus less
hardener is pumped out and the resin/hardener ratio is too high. You can
detect the problem without checking the ratio. If the hardener is
delayed (later than the resin) in coming out of its output tube, then it
is likely that the first portion of the hardener in the pump body is
going back out the check valve into the reservoir. The problem was only
corrected last week. The folks at Michael Engineering have been very
helpful and are sending us a new check valve immediately, but they did
ask us to return the old valve. If you have doubts about your new check
valve, their phone number is (989) 772-4073.

Peter and Karen Barber