LS1 water pump & cooling
First of all, I bought a CSR straight water neck a while back. I'm finally reaching the point in my install that I really looked it over and have a few questions....
1.) It appears to me after taking the pump apart as far as I could easily (and seems to make some sense) that the upper hose is the inlet and the lower hose (t-stat) is the outlet. However, I've read several posts where people reference the upper hose as the pressure side and none the other way around. If the upper is the inlet, shouldn't it then be run to the lower hose in an original SBC application? If it's not, then why is the steam hose run to it?
2.) Why is the LS1 thermostat configured like it is? Specifically, why does it use the housing to apply pressure to the spring instead of just doing it with it's own body? Why is there a hole it covers between the pressure and suction sides?
3.) Wouldn't the use of the CSR water neck result in the equivalent of an electrical short for the cooling system, allowing the radiator to be bypassed? Wouldn't the same problem occur for the heater lines? In which case, the only water making it through the heater core and radiator the small amount of flow from convection?
Please help me understand.....
Last edited by 86atc250r; Jul 16, 2009 at 01:33 AM.
2) that opening that the secondary spring is capping is to quickly heat up the water in the heater core so you can get warm air in the car right away. It is on a spring so that if block pressure gets high it can compress the spring and re leave some of the pressure. The SB therm is loose in the CSR housing to allow some of that pressure release by allowing fluid to circulate just a tad before the therm opens.
3) You will not have a dead spot because the pump pushes the water in a certain direction and once the therm is open it is going to allow the pump to circulate the fluid. The pump is going to pull the fluid from down low and push it through the block, it will go through the block and out through the top of the pump back into the radiator. Likewise with the heater core it is going to push the water through the heater core, there is a check valve on one of heater core hoses so the water is only going to go one direction through the heater core.
Hope this helps some.


