so i got my rebuilt 502 running!!!! YAY right...

well now i have the issue that even with the water ears hooked up nice and tight with the water on about medium, it wont flow through.... nothing out the exhaust nothing in the cooler...(closed loop) took the hose off of the cooler and pump the hose in it to back flush and it flows backwards and come out the drive..(through the pipe, through the oil cooler, water pump) but this was with low pressure on the hose.... re hooked up and nothing... any ideas???

98' 502efi motor converted to carb!

is it my impeller? does seem like that would matter if im pumping water in....
Fresh water pump bad? its making the fuel pump work fine...
clogged????

oddly at the header where the water comes in the bottom to go out, i opened the drain valve and it have like air flow.... exhaust? or is it the pump?

with it open for about a minute on both sides still no water coming out

Sounds Like The Sea Pump Or The Circulating Pump

did you rebuild the sea pump ? if so are the hoses connected for a standard rotation engine? prob. NOT the circ pump(rarely happens) exhaust temp can cause the pressure you feel out the drains. if in doubt remove the drive belt and hook your garden hose after the sea pump and see if you get waterflow out the exhaust (the fuel in the carb should allow you to run long enough to see if its a sea pump prob. or plumbing problem)

Check to make sure you the hoses correct on the seawater pump. If reversed it will not pump.

The circulating pump has nothing to do with water out of the exhaust. Also he stated it was a closed system.

Why did it need building to begin with? Could the failure have any connection to overheating?

Make sure you have a good flow of water from the ears to the raw water pump! The nipple on the inside transom plate, where the hose connects to feed the raw water pump can corrode and pinch off the water supply from the drive pickup. Take the hose loose at the inside of the transom with the ears on the drive and see if water spews out unrestricted.
If this transom hose is restricted then that is where the option is usually to install transom pickup tubes and bypass the drive pickup.

simply inspect the impeller for any damage. If it was run dry, it's probably shot. Vaseline the new one for your dry start.

I had a similar issue and found that the risers (elbows) were corroded and clogged the water dumps. If your impeller is fine that would be my guess!