Overheating while driving

Welcome to 2CarPros.

If there is any debris that is blocking air flow, that would be my first suspect. If turning on the heater helps, make sure the coolant level is full. If it is, then I would suggest flushing the radiator and engine block. Since it does cool down with the heater on, that tells me it isn't related to a bad or sticking thermostat. And, since it happens at highway speed and not around town, that leads me to believe there is a restriction in the system. Also, keep in mind that a leak or faulty radiator cap can cause issues too. Make sure nothing is leaking and that the cap is good.

With that, clean any debris that could block air flow. Also, confirm the coolant is clean and full. If that checks good, then try flushing the system to see if that helps. If you flush the system, I would also replace the thermostat at that time just as preventative maintenance. If it still doesn't, we will need to check for a possible head gasket issue.

Here are a few links that you may find helpful:

https://www.2carpros.com/articles/coolant-leak-symptoms

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

https://www.2carpros.com/articles/symptoms-of-a-bad-water-pump

Here is a link that shows how to pressure test the system. Most parts stores will lend or rent you the tool to do this.

https://www.2carpros.com/articles/radiator-pressure-test

https://www.2carpros.com/articles/coolant-flush-and-refill-all-cars

https://www.2carpros.com/articles/replace-thermostat

And I hope we don't need this one:

https://www.2carpros.com/articles/head-gasket-blown-test

Let me know if this helps or if you have other questions.

Take care,
Joe

Welcome back:

If the engine doesn't warm up when it is cold outside, then chances are the thermostat is sticking open. Is that what is happening? Is the engine not warming up or do you mean you get no heat inside?

Let me know,
Joe

Welcome back:

With that, just make sure the coolant is full. If it is, then I recommend the flush.

Let me know if you have other questions.

Joe