Intermittent overheating

[bstrom1953]

My 2002 Grand Prix, 3.1, automatic, sometimes overheats when I'm not moving fast, like in a parking lot looking for a place to park. I park and discover the temp is way over normal (180), like up to near 210. When I shut off the engine, I hear gurgling like it's next to boiling.

One time it did it I, lifted the hood and the coolant fan was not running even though the water temp was approaching 210 again. Fortunately, for some reason, the fan does come back on after awhile. I looked on the schematic and it appears that the fan should come whenever the a/c is turned on, so I do that and it seems to get the fan to go.

Usually, when I notice the temp going up I can get it back down just by keeping my forward speed up and getting air through the radiator.

I went to Auto Zone. They said there are two sensors: one for the temperature gauge circuit and one for the engine computer. I bought the one for the engine but I don't know where it is located on the engine. I can see a sensor near the thermostat but it's round with three wires and the one I bought is oval and two wires. Can you tell me where this sensor goes? Thanks, bstrom

[aleekat]

So you bought a new sensor without knowing if yours is bad?
The gurgling, can be low on antifreeze or air trapped in the system. And trapped air will cause it to over heat.

[Tech II]

Have to agree with aleekat.........does sound like a coolant leak......with engine cold, first thing in the morning, check level in reservoir AND remove radiato cap and check level of radiator....

Coolant fan will not come on until temp reaches 218-222F.....

I don't think this engine has two temp sensors, only one temp sensor......it reports to the PCM and the IP cluster....located in lower intake in front of and below the thermostat housing,,,,,,,,