Were you and are you loosing coolant?
When you say the rad light blinks is it the light that looks like a battery and thermometer?
If it is the coolant level light blinking and you are not loosing coolant you can try to clean the switch. It is located at the bottom of the coolant resevior. It is not detachable so you must remove the whole plastic tank. Pretty easy a bolt or two, a hose or two, and an electrical connector.
Take the tank to the kitchen sink and fill it with a mixture of automatic dish washing detergent (or any low sudsing detergent) and water. Then shake not stir it vigorously. Rinse and repeat.
Reinstall and see if it helps. The switch is a simple float switch but is not replaceable seperately. If the cleaning does not help you will have to replace the coolant tank. I would check the junk yard.
I agree that the coolant should have been changed. Another often neglected maintenence procedure is replacing the automatic tranny fluid/filter every 30,000 miles. Use only mobile 1 synthetic tranny fluid. Only takes 5 or 6 quarts. Up to 8 if it is way low.
Why is there a question on something being added to the coolant? Gm sealer tabs or ginger root tablets are added by the factory to help seal the system. They are mostly used on aluminum engines after replacing a water pump or 2 or more hoses. Not really necessary with a flush and fill but some shops do use them even then.
The safety inspections vary state to state in the US but will include items such as a serp belt and even fluid levels. The idea behind it is strictly safety. If a belt were to snap or derail in a turn you would loose all power steering assist. Could be deadly. It must have been pretty bad or you got a new/by the book inspection mechanic. Either way it is for your Safety.
God luck and let us know. :)
Thursday, April 6th, 2006 AT 4:24 PM