Started the car today and the low coolant light came on, I thought that's odd because I just burped the system a couple weeks ago and everything was fine. When I started to add water I noticed that the overflow container was full, water was dumping into it apparently, but not being sucked out.

Was waiting for the water to start circulating and looked at the temp gauge and it was up too 242, car never goes over 200 while driving it. I felt the radiator water and it was cold, so I figured the thermostat was stuck. Pulled the thermostat out, put the housing back on and started the car again, still no indication of circulation. Pulled the top radiator hose off and nothing. So now obviously, I'm guessing the water pump was bad, so I go ahead and pull the pump off, and it appears to be good. When you turn the pulley the impeller turns, it should be pumping water. Can the pump still be bad even though the impeller turns, its nice and smooth and easy to turn, no indication of a bad bearing.

I also ran water back through the thermostat housing and also stuck the hose up into the inlets on the front of the block and everything runs clear, so no indication of a blockage. Radiator was just pressure and flow checked when I put the motor back together, so I know thats good.

So do I go for the new water pump, or what do you think??? Appreciate any ideas or comments.

 

If the impeller turns it should be good. What shape are the impeller blades in? If you ran without a themostat and it was still overheating I bet you have an air bubble.

 

I only ran without the thermostat and the upper radiator hose disconnected to see if the water was circulating. I wasn't. The impeller looked fine also.

 

It sounds like the pressure cap is bad if the lower tank is full;
fluid in the lower tank is not being pulled back into the radiator as the engine cools.

 

Bad pressure cap.It's a closed system.Assuming there's no air, water expands into the expansion tank when hot and when it cools it pulls it back into the system.Not likely but could be a bad hose that's only flowing one way.(from the cap to the tank)

 

Ok, don't want to beat a dead horse here, but no one really had an answer to my question. First a little background.

Radiator cap bad, pretty much knew that.
Hoses look ok, gonna replace the bottom one anyway just because of age.
Radiator clean and water flows through it perfectly.
Took out the thermostat.
Stuck a water hose in the water pump inlets on the block and water flows freely through both of them.
Stuck the hose in the upper radiator hose and ran water back down through the block, and it flows freely that way.

Ok, here's the question.

With no thermostat, the top radiator hose disconnected from the radiator, the radiator cap off and the radiator full of water, when you start the car with the system open like that, is there anything that will stop the water from circulating and coming out the top radiator hose. Assuming that the water pump is good.????

 

Short answer: No. Water should flow from the upper hose.

 

The only other thing I can suggest is a collapsed lower hose.If the water can't get into the pump, obviously it can't circulate.

 

Ok, why??