CVR waterpump

[fekbmax]

water pump surging .
disconnected upper hose, rad cap off, water hose in rad keeping system full. start pump to flush out any left over antifreeze. pumps running but no water coming out of engine. let pump run and after a good 25 seconds a massive surge shoots out of engine then nothing again for another 20 to 30 seconds until again a massive surge of water shoots from engine all while keeping rad full. . never had this issue before with a belt driven pump or a old meziere pump. pump is new and apparently not picking up a prime then when it does it looses it. if pump is off water flows freely out of the top hose just by filling the system. turn pump on and no matter how full i get nothing until 20 to 30 seconds then it repeats. no thermostat , open system.
frustrating.
when it surges out its with such force that the hose (1 1/4") straightens out and shoots water a good 5' across the yard.
tried my old leaky meziere pump and i get a nice steady flow while keeping system full and pump running.. 

[jayb]

Never seen that one before.  Is it possible that the impeller is not tight to the pump shaft?  Maybe the motor is spinning but the impeller isn't, then it catches for a while, then stops again?  If you take out six screws on the front of the pump (four short ones on either end, and the two long ones that go through the top and bottom of the motor), you can pull the motor and impeller assembly out.  There is a set screw that tightens the impeller to the motor shaft, maybe that wasn't tightened correctly or something.  I would pull those six screws, start up the pump, and see what you find...

[WerbyFord]

I've had em barf like that when they're hot, not really hot, maybe 190F-200F, but with cap off as you're doing. Hot spots boil in the block then the gas spews out.

Alternately I wonder if your "good" pump has a cast impeller, and the "barf' pump has a stamped impeller that is more prone to cavitation when the system is not under pressure.

If you're running without a thermostat that will make either one of the above even worse.

Imagine that, a 400hp squirt gun! Great fun at pool parties...…..

[jayb]

The CVR pump has a machined billet impeller.

[mbrunson427]

What is your hose setup like? Lower hose too small causing cavitation? Is the radiator filled up? If the radiator isn't full you may not have enough NPSH (net positive suction head).

[fekbmax]

1-1/4" in and out, yes maintained the system full. I think it's a pump issue. Will take the cvr apart maybe the weekend. Just stuck an O ring on the Meziere and slapped it on for now, got a test and tune day Friday.