Is there a way to test if your circulating pump is bad? I put a new water pump impeller it pumps water on the hose but when I put it in at the ramp no water was coming out the exhaust,I was thinking it might be the circulating pump.

Sounds like something is plugged up. Was the impeller in pieces when you took the old one out?

What year, what motor, what drive?

Water was coming out of the exhaust fine when it was on the hose.When I replaced the impeller it only had a little crack in one fin.

The boat is a 1978 Python it has a Sb 350 with a TRS drive

Probably a dumb question but how long did you let the motor run watching for water?

If it was a short time maybe it didn't have time to show up. Otherwise I don't see how water from a hose could make it past the water pump housing and a new impeller....... unless the hoses were connected reversed and it burned up the new impeller and then the water started being pushed thru

The same thing happens if you swap the hoses on the Bravo pump. The hose will push water through the system but the pump won't draw from the lake.

I ran it a couple of minutes three different times.

Only thing left is to have a look at the impeller again. Right now I don't see why it wouldn't be pumping. Could put the hose on it with the motor off and see if water is pushed thru, this would indicate the impeller or housing is trashed

clear water hose method testing - you look for air bubbles and or less volumes of water passing thru the clear hose(s).. This form of testing pin points your problem area(s) and or cooling part(s) issues.

engine overheat is also signs of bad or going bad water circ pumps. But of course there is many other things for overheat / higher temps on top of.

ALSO --- This is how you test Water circ pumps with clear hoses in place of the OEM water hoses

Other forms of water circ pump testing is take of your belt off and spin the water circ pulley in in both directions - it should spin very freely and easy without noises especially bearing noises.

also other testing is to look very closely at the bottom weep hole - look for rust stains and or white water mineral stains out and down from the weep hole. Also when running the motor looks fro water leaks from the weep hole. Also temp swings are associated with a bad or water circ pump going out. Everything here is how one knows that water circ is bad or going bad. The water circ pump seems to be widely missed. IMO of it is over 10 years old I would change them out anyways or for new rebuilds. Totally would not reinstall a used WCP on a new or new rebuild engine.

If you need one I have them made in the USA for MOST MARINE apps including LS and LSA GM MARINE engines and even Ford marine apps.