Overheating?

95’ chevy 4x4 5.7 my mechanic put a new water pump in & thermostat, the next day the coolant temp gage near pegged out & then came down.I took it back & they said the thermostat was ok but the radiator was clogged so, how much? I asked. $500.00 ouch! I think I’ll just take the truck. Well I didn’t check the radiator & just put a new one in myself. Turns out the rad wasn’t clogged so now I have a back up rad. Start the trck & temp gauge goes almost all the way up then comes down rev the engine to 2K rpm’s and up she goes & I can also here gurgling in the heater core, I also flushed everything & back flushed. I ended up pulling the thermostat so I don’t have to deal with the temp gauge. This happened once before. I mean before the water pump & thermostat was changed. I’m done can’t figure this one out. Any suggestions?

I trust you put the t-stat back in. You don’t want to run it without one. It is a 190 deg. right?

Gurgling noises in the heater core usually means there is air in the system.

When the temp gauge pegs, is the engine actually over-heating?
You can use a test rad cap that comes with a thermometer to check for the coolant temp.

You said the rad wasn’t plugged after all. Too bad you hadn’t checked it first.

Throwing parts at a problem seldom work out.

I think you MAY have a coolant temp sensor fault.

When you replaced the rad, did you also replace the rad cap with a new one of the proper pressure rating?

Changed the temp sensor but not the rad cap.

Yeh throwing parts at a problem seldom works good thing I didn’t give that guy $500 to put that rad in.& why can’t you run without the thermostat?