1998 GMC Sierra engine runs hot

1998 GMC SIERRA
178,300 MILES • V8 • 4WD • AUTOMATIC
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DAVE MAYER
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the engine runs hot. I ran low on coolant last week so I filled it up,now it runs hot all the time. Before, it ran half way between 100 and 210degrees. I have replaced the thermostat,water pump checked the hoses (no leaks) and replaced the temperature sending unit. I dont know what else to do . Can you help me with this problem? thank you
Feb 27, 2010 at 7:54 PM
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RASMATAZ
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Could be airlock try bleeding it out-
Feb 27, 2010 at 9:27 PM
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DAVE MAYER
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I have tried that too. I replaced the new thermostat and put the old one back in. It seems to run a little cooler, but it stills stays at around 210 deg. I visually inspected the radiator and found it to be in good shape. Just a side note, I drive about 100 miles per day and would really hate to break down in the boonies. I appreciate your help and anything else you can think of. thank you again. nailbender98
Feb 28, 2010 at 4:55 PM
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RASMATAZ
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Do you have a boil over situation? if not-could be just the coolant temperature sensor out of calibration or the gauge itself-now if in fact there's boilover get it block and pressure tested.-Rad cap is it in good shape?
Feb 28, 2010 at 5:02 PM