One of my motors gets NO water until I remove one of the hoses going to the exhaust from the thermostat housing(aftermarket). I run a crossover peice and have great pressure 25psi after but none at idle. I may have hurt my impellor but it is new as is the plastic housing. Do the little balls on a spring in the stock housing keep the water in the motor after shutdown? Seems vapor locked or something??My therm-stat housing only has 2 out for the exhaust.Like I said,if I remove one hose,let it run a few secs it starts to circ then I am good for the day. Next day ,same prob,same fix. Just a weak pump? I don't know. My stat has 4x1/8" holes drilled in the edge and is a 140 deg.

Do you have a bypass on the Cross over?

Jon

nope. The other motor is set up the same. Hasn't been a prob until lately. Can a weak pump do this and still create 25 psi at speed?

OK,Pump is perfect,just took it apart. You can feel it pulsing air and if you remove one of the hoses from therm-stat housing and after it gets hot and you rev it up a few times HOT water comes thru then it's good for the day. Show 0 at idle and up to 30 psi at speed. Confused.........

Sucking air anywhere? May be a slight leak at in the hose on the pull side. An air leak could make it harder to prime.

That's what I wondered. I'll have to tighten evrything and try some more