99 Cavalier overheating

I have a problem with a 99 Cavalier. It will overheat while sitting, upon occasion. Most of the time, it overheats when the heater is on...heater core? There is often a sound like rushing/gurgling water that comes from the passenger dash area. Any ideas?

Low coolant/air trapped in system.

The coolant looks to be full, and there seems to be no clogging. Could the water pump account for the rushing water sound?

Has the coolant system been opened recently? How is the heater output?

Are you only hearing the this "gruggle/running water sound" when the vehicle is at or ready to overheat?

I don't know the exact temp on a Cavalier that the fan is to kick on, most GM are 'round 220ish, verify your fan is working.

I opened the coolant system to add water after the first overheating. The sound occurs when pressing the accelerator, when in drive, and happens when cold or hot. The fan does not seem to engage, however, the car will sometimes overheat when driving. As far as the heater output, I do not know how to check.

Heater output is very simple, when you put the temp knob on red, and the engine is temp, how would you rate the amount heat output from the vents?

From the way is sounds you have a mass amount of air in the system somewhere somehow. You are hearing it upon acceleration because the pump is trying to push the coolant through the system but is only doing so in spurts.

The fan (radiator) not coming on or malfunctioning is also possilbe as a result
of air.

Might want to cocider some system maintnance and replace the Thermostat, radiator cap and frech coolant mix.

How would I go about flushing the system. If I were to drain the radiator, would that be sufficient? And for flushing, how does that work? Do I fill with water and run for a little while?

You get a flush kit, made by Prestone for about 2-3 bucks at you local parts store. It has a a "t" fitting you put in one of the hoses and just pump water through. Never run the motor with no coolant in the system :nono: Not only do you run the risk of engine damage, but run a high risk of damaging the automatic transmission when the engine is overheated.

If the coolant is decent condition, a flush kit isn't completely a must, jsut checp insurance in my eyes.

Thanks for the help, this gives me a lot of good ideas. Better to start cheap, cause if this dies not solve the problem, it is still good in-expensive maintenance. Thanks alot.

No problem, it's always good to eliminate the cheap things first when you're not sure what the real problem is. :thumbsup: