I just put my 79 challenger on the water for the first time. I got the boat knowing the was a problem with the motor, I had it pulled and fixed and it runs great. I took 1 trip around the lake with no problems then while idling in I noticed the motor heating up I looked in the back and no water was coming out from the thermostat outlet hose in the back of the transom. I just had it hooke up to the hose before taking it out and i had no problems with circulation. The problem has go to be with the pump or a clogged intake hose. I am waiting for it to cool done before I start diagnosing it. The question i have is my pump is a jacuzzi yj, I know they operated a lower pressure but it should put enough pressure to circulate thru the block, right ? Someone suggested the maybe that pump needs to be ran with a water pump but that dosent sound right. While @ 3k-3500 RPM arount the lake I had no temp problems. Any ideas ?? Thanx in advance..

That was the first thing I was gonna look at when it cools down. Thanx brother !!

this is why i check my dump while im idling out of the no wake zone

I had a similar thing happen when the bearing in my pump blew up....the impeller got pretty tore up and clogged the cooling port with impeller debris.  I'd check the pump out.

Another thing you can try is to rig the garden hose up and back flow the cooling system. that way if there is any debris it goes back out. Depending on where you boat , there could be all kinds of crap floating around in the water and can easily be stuck in the cooling system somewhere.