sentra overheating

[nurseduran]

my 2000 sentra (1.8) all of a sudden started to overheat and blow cool air from heater. thermostat ok, pressure test ok, water pump and fans working, radiator ok, coolent level ok. any ideas???

[dragon285]

I would check flow through radiator. Remove cap and run until thermostat opens. Check flow by looking into top of radiator. Sounds like the water pump is not working.

[nichols1992]

There's a circulation problem somewhere, either your water pump isn't pumping, your radiator is clogged, your thermostat is stuck, your head gasket is blown, or you have air in your system. You ruled out the water pump, the thermostat, the radiator, and the fans, so I'd do a leak down test on your cylinders to check your head gasket. If that passes then I would try to bleed the air out of the system.

[jwerty1]

headgasket

[carmo]

Top off the coolant and put the rad. cap back on. Run the vehicle until you hear the cooling fan cycle and you have built up pressure in the cooling system. Then remove the coils and the spark plugs after cutting off the engine of course. If the head gasket is leaking, the pressure from the cooling system will push coolant into the cylinders. Fortunately for you, a head gasket job on a 1.8 is a piece of cake.

[jwerty1]

especially if letting it sit overnight, you notice it misfires for a couple seconds when starting up