The best thing to do is to start as simple as possible, that way you don't end up replacing parts that you didn't need. First make sure that your radiator is completely full of coolant and that the system is completely bled of all air.
After that, here is an incomplete list of areas to check:
If your leaking/losing A/F check:
1. TB gasket
2. Coolant elbow coming off of the intake manifold. (it is possible for your car to have 2 elbows)
3. Upper and lower intake manifold gaskets (check the front and the back of the intake manifold and look in the low areas and see if there is any coolant that has leaked out.)
4. Check every hose and and hose clamp for evidence of leaking and tighten or replace as necessary.
5. Make sure your radiator isn't leaking.
6. Check the water pump seal and weep hole for evidence of A/F, if present replace water pump.
If your not leaking A/F:
1. Make sure your radiator/AC condenser fins are not full of road debris. (blocked airflow)
2. Make sure your belt is in good condition and that the tensioner is keeping correct tension.
3. Make sure your radiator fans are working. (You can test this by either waiting until your engine gets up to temp and see if they come on, or you can turn on the AC and watch to see if they come on, with the AC on they should come on right away.)
4. Do a coolant flush. (this will help removed any mud caused by Dexcool, or any other blockages that there may be.)
5. Change Thermostat
If all else fails go to an autoparts store like AutoZone and get a coolant pressure tester(loaner tool). With your engine cool, take off the radiator cap, put the tester on the radiator and pump the tester up to about 16-17 psi. Observe the gauge, it will hold pressure if there are no leaks. If it doesn't not hold pressure, check around and see if you can see any coolant leaking (check under the car to see it dripping, even look inside the passenger compartment, that will check to see if your heater core is leaking). Fix or repair what you find to be leaking. Sometimes it depends on how much coolant has leaked, but with leaked coolant all over the engine it may be hard to locate where the leak is, if this is true for your engine, make sure to clean the areas where here is coolant present and retest.
If the system does hold pressure move on to testing the radiator cap. The kit contains an adapter that is used for testing the cap. Put it all together and pump the tester up, careful to watch the gauge to see when the cap relives the pressure. You should hear the cap relive pressure about 15-17psi, if it releases it earlier your cap is faulty.
As to your question about Dexcool, I would say a good majority of us have changed to either the green or Peak Global A/F. Dexcool has been strongly suspected of part failures and overheating since GM started using it. If you decide to go with the green, it is recommended to be changed every 2 yrs, if you use Peak Global you don't have to change it. According to their site you can use it for life If you do a coolant flush.
Good luck with finding out what is making your engine overheat, if none of this works for you, it could be something more serious, like possibly a head gasket (worst case scenario).
Either way let us know what the deal was. :th_thumbsup-wink:
