My husband took our 1992 Pontiac Grand Prix,3.1L to a Repair Shop to have them do a pressure check on the radiator. Jeff (my husband) has replaced and done everything to the cooling system,including just having the radiator rodded out. He still didn't think there was good circulation.The Mechanic told Jeff when the other employee came back from lunch they were going to do test at 16lbs.Jeff picked up our car and told him "no charge". On the way home the car died. Jeff thinking he was out of gas,(gauge doesn't work)put gas in and heavy tapping from engine is now being heard. Jeff checked the oil and it was brown colored. He changed the oil (kept it) and no change.There was absolutely nothing wrong besides circulation! This occured today,1-6-03.He's going to shop tomarrow.Need Advice Please!! "Thank You"