I got a seriously bizarre (or stupid) problem with my cooling system.

[Trust_RPS13]

So it's just like my header says.

To make sure i'm not stupid. The Water comes out of the radiator, through the uppper hose into the block, pump spins, h2o heats and pops thermostat, and back to radiator???

Anyways if i'm right or even if i'm not i've got a problem. Either somehow my h20 flow has reversed casue it's now coming from the bottom into the block or well i don't know what else it can be.

I've replaced the thermo, h20 pump, radiator. I've checked all the inlets and outlest with a hose and h20 comes from everyhole. So the problem is that with the thermo in h20 doesn't complete its cycle the bottom hose never gets hot. But the heater works. So i pulled the thermo and put it in a pot of h20 and it opened at 170 degrees. so it's good. The h20 pump i think is good cause the heater works and without the thermo in everything works fine. runs cold but that's all.

What seems to be happening is because the h20 coming up from the bottom the h20 in the block heats and thermo pops but the the cold h20 hits and closes immediatly. In theory i could let it run and eventually all the h20 would heat up but i'm kinda afraid cause the pressure build up already blew one pump!!!

Any ideas??? some one please prove me wrong!!!! or if you have any ideas let me know. I'm running no thermo right now but i gotta pass cali emissions before the 16th and it's not gonna pass with it running this cold!!!!

[Ubernoober]

Coolant is drawn from the bottom of the radiator into the water pump. It is then pumped through the block and cabin heater core. It then passes out the upper radiator hose and into the top of the radiator.Unless Nissan did something unique with their water pumps, there is no physical way for it to develop enough pressure for the pump to "blow".I think you are correct that the thermostat is working correctly. Checking it in a pot of hot water is a good way to find out.

Here is what I think happened and what your problem is...You arent properly purging the coolant system of air. Thats it. All the symptoms you mention including "blowing" a pump (you actually probably just destroyed the seals because it wasn't being lubricated by water).Here's what to do. Replace your thermostat and follow the FSM instructions for replacing coolant.