Overheating

[lostinspace]

I am truly lost in space on this one. I have an 04 Sentra with a 1.8 with at/ac
it has 110000 miles. It ran hot enough to push a large portion of the coolant out of the overflow. I was close enough to home to that I let it cool off and got it home. I topped off the coolant, started it and let it idle for quite some time. Temp guage stayed in middle, noticed that hoses were not warm enough for the time that it had been running but the collant fan never kicked on and there was no heat comming out of the ducks and the heater hoses were cool to the touch. First instict was to change thermostat, changed it let it idle for quite some time to make sure of no air pockets. Took for test drive and did not get 2 miles down the road before it started to overheat, slowed down to turnaround temp guage went down to normal. Started to come back and it started to overheat again this time to the point that it kicked the coolant fans on. Done some reading and felt that the waterpump impellers were worn, replaced waterpump with no help in fixing problem. No loss of coolant and no bubbles comming up in radiator and no water in oil and exhaust is normal does not point to headgasket blown. Any ideas on what it could be????

Open to all suggestions other than crushing, cant afford that option

[dartman]

It,s possible the thermostat stuck and didn't allow enough coolant flow. Once the coolant overheated and pushed into the overflow bottle now you will have air in the system. I would change thermostat--refill and bleed air out small bleeder , I think it,s near the thermostat housing and let it run until all hoses are hot and fans kick on. Then road test

[boyrs]

might be a bubble giving you all your probs. need to refill fluid under pressure

http://www.nicoclub.com/FSM/Sentra/2004_Sentra/ma.pdf bottom of pg 17