03 Overheats

'03 Durango with 4.7 liter V8 and daughter called (husband in IRAQ) to say that she had pulled car over as it was blowing steam from under the hood. I drive to the car, opened hood and found coolant everywhere. I checked radiator cap and it was way loose. I tightened cap and added water to overflow bottle and followed her home. When home she informed me that the temp gauge would go almost to the red, then cycle back to normal, and immediately repeat the process. I let truck cool down and added three litres of water to the engine (below the radiator cap). I am about to restart her and f I am correct and she continues the cycling I am assuming a thermostat that is cycling. I assume the thermostat is below the alternator and I will need to pull the alternator to get at the stat (I am on my way to pickup a Haynes manual for the Durango). anyone care to wade in before I begin?

Read the manual about filling the system, make sure there is no air in the system. If possible, pressure test the system for leaks.

Thanks for the response. I have an older BMW and am familiar with bleeding air from the system. After we got the car home and she cooled down, I added three liters of water into the system, fired her up with radiator cap off, squeezed the upper hose several times during warm up, then put radiator cap back on and she ran fine with needle well below the mid point of the gauge. I took her for a drive and she is fine. Just needed an air bleed and more coolant.

Thanks for the response. I have an older BMW and am familiar with bleeding air from the system. After we got the car home and she cooled down, I added three liters of water into the system, fired her up with radiator cap off, squeezed the upper hose several times during warm up, then put radiator cap back on and she ran fine with needle well below the mid point of the gauge. I took her for a drive and she is fine. Just needed an air bleed and more coolant.

I don't see where you added coolant to the system but appeared to add a couple gallons of water. If that is the case, I would drain about 6 or 7 quarts out of the radiator & replace it with pure fluid. Get a coolant checker whilt you're at the parts store. They're cheap. Use an extended plastic tube from the petcock to a gallon jug so you can know how much you've drained.

The vehicle may be running fine right now but will have problems when more intense heat or cold conditions occur.

Also check the resevoir everyday for a week or so. My Durango 5.9 almost always burps itself & uses a quart or so of fluid in the process after every system flush/replacement.

Mae Culpa, I did add water at first, then after we got her home and cooled down I added equal amounts of water and anti-freeze. did a freeze level test and she is at -34 F so we are good there (though it has never reached that point in SE Virginia). local Advance was out of Durango service manuals so I am branching out to Auto Zone and Pep Boys for the book (if I need to change the "T" stat I need to know if it is indeed below the alternator support bracket and if I have to remove alternator and serpentine belt to get at the "T" stat housing). Thanks for the response.