Hey guys,

I have a 1975 ford 302 in my rx7. I have a electric water pump hooked up to my rad. I had my uncle over who used to work on old cars lots and had a repair shop and stuff and he told me that my water pump cannot pump up hill. I had this car running through and the water pump seemed to be working. He advised me to relocate the rad hose you can see in the pic so it does not go over the valve covers. However this is hard to do as this is the easiest way to have it hooked up. Is what he says correct? I did have it running and it seemed like everything was working.



Rad hose that goes over top engine.

 

Pumps pump stuff. That's why they're called "pumps." If you only want stuff to flow downhill you don't need a pump.

However, unless I'm having a brain freeze right now, the water pump pushes coolant through the engine, out of the thermostat housing, into the top of the radiator, through the radiator, and then back to the water pump. That still works fine as long as it has water to pump. But with the run you have you might have trouble "priming" the pump. It won't be able to suck water up and over the engine while it's only pumping air. Once you get the air out of the system it'll be fine, but be careful at first.

 

i don't quite understand the way you have it setup. you should draw from the bottom of the rad,
and the way it is now will be very hard to get decent suction.
why not rotate the pump so the inlet is on the passenger lower side?
or come out of the pump and down, then across to the lower rad outlet.

 

I would agree there are better ways to set it up. But the water pump doesn't need to pull much at all. A cooling system is sealed and (ideally) has no air in it. So the pump can push coolant through the entire system and back to itself. Suction isn't a factor.

Of course, as I said in my earlier post, that doesn't hold true when that long intake line is still full of air after refilling the cooling system. Then the pump does need to be able to pull water in, and it won't be able to very well at all.

 

but that will only work if the system is full and pressurized. if the radiator is low, there is a possibility the system can suffer cavitation on startup.

 

Agreed (and getting over 10 characters in the post)

 

This is the way the water pump came assembled. I'm not sure if it clears the pulleys properly if i were to unbolt the flanges on the pump and flip them around. I think the large flange that is visible might have issues with the pulley. As it is, it is pulling from the bottom of the rad and then pushing it through the engine, through the thermostat and then into the upper rad?

 

yes, but it is pulling from the bottom of the rad, up over the engine and then back down.

this gives it a very good chance to suck air and loose it's prime, or even worse cavitate, and not work at all.

 

If it is a sealed system with liquid in the overflow bottle which i have installed and is not in this pic but it is near the front right of the rad where the hose is, then it will forever be sealed and this will not be an issue?

 

maybe, maybe not. remember, air in water looks for the highest point.
so if there is air in the system, it is going to go to the suction line on top of the engine.
a big enough bubble can cause the pump to loose prime and cavitate.

 

I dont understand what you recommend. Moving the hoses isn't easy since most places don't offer hoses that are easily bendable in that size.