Car running hot

Did you close the petcock ? if not it may have broken recheck your work.

These guides can help us fix it

https://www.2carpros.com/articles/engine-overheating-or-running-hot

and

https://www.2carpros.com/articles/car-is-leaking-coolant

Please run down these guides and report back.

Check around there for cracks or breakage they are only plastic tanks with aluminum fins so it may have cracked either at the petcock or lower rad hose if you took it off there. We have no pics of that so we can't send anything like that to you. It may also be a loose hose at pump and leaking down so check there as well.

If you're hearing that under the hood, look for bubbles in the coolant reservoir. If you see them there, suspect a leaking head gasket. The clue, as you mentioned already is there's no steam associated with those bubbles.

Are you actually overheating or boiling over if not could be the gauge or the coolant temperature sensor misleading you-If not could be air in the system, clogged radiator or a malfunctioning water pump

Could be airlock in the cooling system try getting it bleed don't work its time to get it block and pressure tested.

If you feel it is raising to a point of concern and it has not done it before, there is a problem.

The fact that it lowers with the heater on is not uncommon. The heater core acts as an additional (small) radiator where coolant has extra time to cool.

On the other hand, the AC places an extra load on the engine that can cause it to run hotter.

Now, if the car only heats up when you are at a stop, make sure the cooling fans are running (when the gauge shows hot). If they are not, they need to. When the car is sitting, there is no air flow through the radiator to cool the coolant. As a result, the fans draw the air through it to keep it cool. When you drive, air flows. Therefore, if it is heating up while you are moving, I would suggest replacing the thermostat. It is a cheap part to start with and if it is sticking, it could be causing the problem as well.

If you want, we have a "how to" for checking the thermostat on our homepage under the DIY section. The hardest part is removing it. However, I would just replace it if I remove it. They are like $5.00.

Let me know if this answers your question and helps. If you have other questions, let me know.

Joe

You do not want the engine to overheat. If it does, it can cause other problems such as a blown head gasket, warped head. Because I am not there, I truly do not know how hot it is getting which makes it hard for me. Regardless, chances are it will continue to get worse over time. I would first start with the thermostat. Also, since you have to drain the radiator regardless, go to the parts store and get yourself a good radiator flush and flush it. That way you can get two jobs done in one and not have to re-drain the radiator if the thermostat does not fix the issue.

Hope this helps.
Joe

Can you tell me what they have checked so far?

When it goes to 3/4 the fans come on and it drops to 1/2. If you were overheating you would know. A restricted radiator can cause this or a faulty coolant temperature sensor. Thank you for using 2CarPros.

If everything is good with the cooling system, the only thing I can think of is a bad temperature sending unit. That is what sends the signal to the gauge. However, I cannot understand why it would do what you described unless there is a resistance problem within the switch itself.