Well, my 98 blazer's temp. gauge goes from normal (Halfway) to hot or 3/4 way on the gauge. It will stay there for a few seconds then go back down. I just had a new heater core put into it. Could it be that? When it goes back down sometimes my heater starts blowing harder. So far it has never went into the red, but I know it shouldn't be fluctuating back and forth like this. Does anyone have any suggestions for me? Thanks a million if you do!

 

You might have an airlock in the cooling system. Check the radiator level, when it's cool, to see if it's low now. If your problem continues, I recommend changing the thermostat.

 

Thanks a bunch for youre reply. It is greatly appreciated!!! I'll leave a comment whether it works or not! Thanks again!!

 

solid advice

w/ engine cold remove the radiator cap start truck let it warm up to ensure all air pockets are released and let it run awhile like this

shut truck down let it cool and check your lvl in the radiator (top off if need be

replace cap, start and test again.

if same happens then replace your thermostat

(or just replace thermostat and refill system and purge it)

I have found that when the heater cores are faulty and need replacement, normally suggest the thermostat also. Most people dont replace these avg 5 yr life span. Coolent 2 yr avg. (Dexcool never use and remove asap if already equipt in system)