97 Cavalier Z24 / 2.4L Heat Problem!?!?

So i own a 97 cavalier with the 2.4 L in it. I've only owned this car less then 2 months. The car has 182,xxx miles. When i bought it, it ran fine and didn't give me this issue until later on. So here I'll go ...

When i drive the car for a period of time, warm air comes out but when i take my foot off the gas to come to a stop sign or anything for that matter then coldish air comes out. So pretty much the RPM'S have to stay up for hot heat to come out. The temp gauge usually reads in the middle but the longer i drive my car the more the temp needle will creep up closer to the red. I never let it get that close, If it does i pull over and turn the car off. I then check under the hood and it seam's to me like it's clogged or something like its trying to come back out of the Over Flow Tank. I then slowly untwist the cap and let the coolant poor out, allowing it to settle. By the way the coolant is Coldish always!. At the same time its making gurgling noise's.. Once its finished making noise's and over flowing from the tank i then start my car up and get home with no problems. I then go back out to my car the next mourning and the coolant seemed to settle because the Over Flow tank barley has any coolant in it.

I have had a few mechanic's look at it. What it comes down to is them telling me that i need a new Water Pump because the Impeller's probably aren't any good anymore. I get other people telling me its my thermostat and its not functioning like it should. I am really confused as to what the problem could be???

I have a new thermostat sitting in my car because i haven't had a mechanic change it yet because i want to know what the problem could be first for sure.

I have a new mechanic that say's he can change the Water pump for me this Sunday. All i would have to do is buy the the Water Pump and Coolant. He is willingly to help me out so he might charge me less then $100 to do it. I have to yet talk to him about the labor price but he said to me that he can work something out to help me.

Can i have anyone's advice to tell me what i should do??

Thank you for reading this!

I would start with the thermostat. It is the easiest and least expensive.

Also if the temp gage is reading hot, if the temp sending unit is on the engine side of the thermostat and not the outlet hose side, the coolant in the block is hot. The coolant coming out of the radiator is not hot. I would have to presume that the coolant is being forced from the bottom of the radiator to the top. Which would be cool because it has been exposed to cooling air.

I would start with the thermostat. It is the easiest and least expensive.

Also if the temp gage is reading hot, if the temp sending unit is on the engine side of the thermostat and not the outlet hose side, the coolant in the block is hot. The coolant coming out of the radiator is not hot. I would have to presume that the coolant is being forced from the bottom of the radiator to the top. Which would be cool because it has been exposed to cooling air.

so by what i said you think i should just try and get the thermostat changed? I have felt the thick hose thats on the right side of the engine that comes from the right side of the radiator and that does get hot, But any of the hoses that go to the Coolent Over Flow Tank to the Radiator is Cold, I think i had said that correctly??

The way I understood it is that only cold coolant was being spewed out. Sorry.
I would still go with the thermostat as the least expensive fix at present.
Has it ever been changed that you know of ?
How much coolant do you have to add after the resivoiur settles ?
Because it kind of sounds like you may have a head gasket going. Pull the plugs and seee if any of them are wet with coolant. If not you can pressurize the cooling system then pull the spark plugs, crank the engine and see if any water comes out of the plug holes.

The way I understood it is that only cold coolant was being spewed out. Sorry.
I would still go with the thermostat as the least expensive fix at present.
Has it ever been changed that you know of ?
How much coolant do you have to add after the resivoiur settles ?
Because it kind of sounds like you may have a head gasket going. Pull the plugs and seee if any of them are wet with coolant. If not you can pressurize the cooling system then pull the spark plugs, crank the engine and see if any water comes out of the plug holes.

I think the head gasket was replaced by previous owner or sometime way before that. I had already changed the plugs awhile ago. they seemed fine. Dry and normal. Nothing was wet.

I usually have only poor a cup of coolent back in the Tank. Not a whole lot. Lately i didn't put as much in because there is alot in the block/Radiatar i was told. So now it seems like it doesn't act up.

Im going to try the thermostat though this sunday.

Thank you