NHTSA Complaint #10283990 — 2000 CHEVROLET BLAZER

I HAVE A 2000 BLAZER LT WITH 128,000 MILES THAT HAS HAD HEATING/COOLING SYSTEM PROBLEMS FOR SEVERAL YEARS. HAD DEX-COOL IN SYSTEM WHICH I MONITORED REGULARLY TO MAKE SURE HAS TOPPED UP. GM STATES DEX-COOL IS MAINT FREE TO 155,000 MILES. WHEN VEHICLE REACHED 100,000 MILES, I BEGAN TO LOOSE HEAT. I NOTICED A CRYSTAL-LIKE RESIDUE FLOATING IN COOLANT. DRAINED, BACK FLUSHED HEATER CORE AND FLUSHED SYSTEM 3 TIMES THEN ADDED PRESTONE (GREEN) COOLANT. AFTER ABOUT 10,000 MILES BEGAN TO LOOSE HEAT AGAIN, REPEATED FLUSH AND FILL. EVERY YEAR SINCE, WHEN COLDER WEATHER SETS IN, THE SAME PROBLEM SHOWS UP AND I GO THROUGH THE SAME FLUSH AND FILL PROCEDURE. DEX-COOL HAS LEFT SO MUCH SLUDGE THROUGHOUT THE SYSTEM I CAN'T GET IT ALL OUT AND IT CONTINUES TO PLUG THE SYSTEM. I HAVE REPLACED TWO WATER PUMPS, THREE THERMOSTATS AND HAVE SPENT HUNDREDS OF DOLLARS JUST DOING FLUSH AND FILLS. ENGINE TEMP WILL BE GOOD FOR THE FIRST FEW WEEKS AFTER A F & F THEN BEGINS TO RUN HOT AGAIN WITH THE SMELL OF COOLANT IN AND AROUND THE VEHICLE. THERE ARE NO VISIBLE LEAKS ON THE GROUND OR ON THE BLOCK. ALL ENGINE VACUUMS CHECK OK. ALL OTHER REGULAR MAINT DONE WHEN REQUIRED. LAST F & F DONE 08-30-2009 AND VEHICLE IS STARTING TO RUN HOT ALREADY/AGAIN. *TR