2005 GC 5.7 IS HEATING UP, COOLING FAN REVS UP FAST AND LOUD, BUT NO HEAT INSIDE. ONCE THE GAGE GOES UP. I LOOSE HEAT, THE COOLING FAN CRANKS UP AND ONCE IT COOLS DOWN, I GET HEAT AGAIN.

i REPLACED THE RADIATOR AND HEATER CORE ABOUT A YEAR AGO WITH NO PROBLEMS UNTIL A MONTH AGO. COOLING FAN STARTED SURGING, SO I REPLACED THE THERMOSTAT AND EVERYTHING WAS OK UNTIL THE FAN STARTED SURGING AGAIN.

TOPPED OFF THE COOLANT RESERVOIR AND A FEW DAYS LATER, ITS EMPTY. NO COOLANT IN THE OIL AND NO LEAKS ON THE GROUND OR ANYTHING UNUSUAL COMING FROM THE EXHAUST. SEEM TO BE LOOSING COOLANT BUT CANT FIND ANY LEAKS.

ENGINE RUNS FINE, DOESNT SMOKE, DOESNT BURN OIL, LEVEL STAYS CONSISTENT AND IS SUPER CLEAN.

I'M THINKING THE WATER PUMP IS GOING, BUT I HATE TO REPLACE IT ONLY TO FIND OUT I OVERLOOKED SOMETHING SIMPLE. I'M GONNA TO TRY AND BLEED IT TO SEE IF THERE MIGHT BE AIR TRAPPED.

IF ANYONE HAS ANY IDEAS, IT WOULD BE GREATLY APPRECIATED. ITS BEEN A GREAT CAR, BUT IM TIRED OF WRENCHING ON IT BUT WOULD RATHER FIX IT THAN REPLACE IT

THANKS IN ADVANCE FOR ANY SUGGESTIONS

 

Have you checked the actual level in the radiator?