2004 DF140's peeing/not peeing

[courantpublisher]

I have a pair of DF140's on a 25' World Cat with less than 400 hours and they are not putting out water regularly. Zuki man said possibly sand or grit stopping up holes so I ran water down both of them. Can't really tell any difference, but I have put 50 hours on the motors since I noticed the problem and the heat alarms are not even thinking about coming on.
Someone told me they only put out water when the thermostat opens, is this correct? I am old school, and if it ain't peeing, you got a problem? I love these motors and don't won't to burn them up. HELP!

[boats.net]

I haven't seen many of the DF140's, don't think it controled by thermostat but might be, may need to blow out water check hose with compressed air to dislodge any sand in it.

[mitch]

The water goes through the pisser all the time as it keeps fuel return and oil cooler cool, water should be running all the time from pisser there is a small hole in it is it clean they do not take much to block up.

also check water pressure valve as it may be jammed open it is on the mid leg

[dmaschi]

when was the last time you changed the water impeller?