Coolant issue with 1997 blazer

I had the same problem with my 1999 grand am .I changed water pump, thermostat. I heard the Pontiac engines , 3.4 had overheating problems one is the intake gasket if your losing water but don't know were its going its leaking at the intake gasket and burning off or if you check the oil cap or the dip stick and theres a milky substance on them it would be your head gasket I had to change my head gasket and while I was there I changed the intake gasket too. I haven't had any problems sence I changed them hope this helps. Jack

What you are describing is a cooling system low on coolant or a sticking thermostat.
I might leave the thermostat out and drive it a few days to see what happens. There could be something in the system that is restricting flow, or it could still be low on coolant.
Its possible something is not right with air flow thru the radiator or the fan clutch. There could be a restriction in the ac condenser.

An intake gasket could cause both problem but you would notice a loss of anti freeze. You said you just replaced the thermostat. With that in mind I think you may just have an air bubble in your cooling system. Before you go and spend alot of money try this. When your car is cool take off your radiator cap then start the car. Make sure you keep an eye on the cars temp. Keep in mind that the temp will run a little hot, but don't let it get into the red. Have your coolant in hand. Let the engine run with the radiator cap off. The anti freeze in your radiator will raise and fall as the thermostat opens and closes. If any coolant spills out ad a little more. Do this for 20 to 30 minutes. If you have an air bubble this should get rid off it. I hope this helps you out.

Thanks for choosing FixYa and welcome. The most common issue would be a sticking thermostat or a bad one. You could also have a bad head gasket, valve, or impeller. You have already changed everything else.

Have system pressure tested when cold and full to top. Pressure test will force coolant out and you will be able to trace the leaks location. Hopefully it's a small hose leak and not a major problem like a blown head gasket or cracked head.

Have you changed the water pump ?

you have an intake or head gasket leaking internally..

Most Hondas and modern car fans can and do run at will. 215 on a scan tool is just reading the sensor and variation is ok. A temp gun is more accurate. Ill bet your gage is still normal. I have a honda and the fan runs at times when I get out. Normal

Hello,

The chevy blazers are known fior heater core issues clogged going bad etc... The reason im saying this is because the only reason i could see you having a problem with the temp not getting hot enough is because then your heat in your car isnt getting hot or its taking super long to get luke warm, is that correct? If so 9 times out of 10 its a bad heater core...

Thanks,
Steve

It could be your head gasket.