electric water pump

[TurboTom]

'(For an example of a positive displacement pump for liquids, tear apart an oil pump for a gerotor type, or a fuel pump for a variable-volume chamber vane type.)"

Sorry I have to disagree. I guess my centrifical gas powered water pump really did'nt pump water from the creek to the pond up a 120ft rise
72 psi including the rise and pipe wall friction.
You can't move any fluid without a pressure differential.

If I am wrong, please don't tell the fish...they seem awfull happy

[Plechtan]

The heater/bypass port is threaded 3/8"NPT - so just a plug can be put in there (that's pretty standard for most water pumps in general on American vehicles - that's why I've never gone and bought one of those damned cheap stamped hose nipples for a water pump. Get brass pipe instead, make an ell out of it - and that keeps the rubber hose away from the belt and backside of the pully as well.)

Note that the pump is an automotive cooling system is merely a circulator, it does not RPT /not/ generate any pressure! Pressure in the system is a result of temperature - and it is this pressure that works to move the boiling point of the coolant upwards (1psig of pressure = 3*F rise in boiling point of water and aqueous solutions. 212* at STP becomes 242* at 10psig, for instance.) The pump, being an impeller type and not a positive displacement type, doesn't generate pressure (by the same token, a centrifugal supercharger doesn't directly generate any manifold pressure - it works because of inertia [speeding up the airflow in the manifold] and due to the compressibility of gasses. Liquids don't compress.

(...

I disagree with some of your statements, for example the sump pump in my basement is centrifugal and it does make some good pressure. Water or air will only flow if there is a pressure differential. The pressure in the coolant system produced by the heat of the engine has no effect on causing coolant flow. If the pressure in the coolant system is the same everywhere, then it doesn't do anything. You need more pressure in the block and less pressure in the radiator to cause coolant to flow. In the case of my sump pump, when the pump spins water is moved and the air pressure pushing down on the water in the sump pushes it into the pump to replace the water that was moved by the impeller. I believe the terms pressure side and suction side are generally used when referring to a pump.

I agree that pressure is created by the heat of the engine, but additional pressure is also created by the pump. to measure the pump pressure you would need 2 gauges. One on the radiator and one in the block on the pressure side of the pump. The difference between the two gauges would be the pump pressure.

Pumps that are not positive displacement still produce pressure. You can block them off completely and not cause damage, but if you put a gauge on them when they are deadheaded you will still get a reading.

[5-90]

I maay have to dig around to see if I have a pump or three floating around -

That's funny. I just did a water pump yesterday and tossed the old one into the pile, there were already 4 of the darn things there already.

/end thread hijack

Hm - I wonder if you can wedge all four of those into a large "Flat Rate" Priority Post box for fifteen bucks...?

Don't throw any of those away just yet!