Engine hot while driving and cools when stopped

JASONTYE

MEMBER
2014 CHEVROLET MALIBU
2.5L
4 CYL
2WD
AUTOMATIC
145,000 MILES

I was driving to work this morning and noticed that my engine was running much hotter than normal but would cool down when I slowed down or stopped at a red light. Got to work and noticed coolant pooled up in the front bumper on the driver side. We noticed the coolant tank was nearly empty even though it was where it was supposed to be last week. We put coolant in and ran the engine but couldn't find any leaks. I'm lost.

5 Replies

SQM

MECHANIC
6,383 POSTS

Hello,

When an engine overheats the coolant system goes under more pressure than the radiator cap can handle. This will make the coolant come out of the system through the cap.

After filling up the coolant. How long did you run it?
Did it overheat again?

There are several reasons why an engine can overheat. It could be due to a stuck closed thermostat, bad water pump, being low on coolant etc.

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

Let me know what it does if you just let it idle or drive again.
Thank you.

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Friday, January 21st, 2022 AT 9:50 AM

JASONTYE

MEMBER
3 POSTS

Thank you for your reply. I just took it a few miles down the road and back. I'm idling it right now and so far, everything looks okay. But when I stopped at the gas station where I turned around, there was a small pool of coolant. I don't know how to find where it's leaking from. Could it be the radiator cap?

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Friday, January 21st, 2022 AT 9:56 AM

SQM

MECHANIC
6,383 POSTS

It could be a weak cap that allows coolant to escape. And when the coolant is low the engine will overheat.
See if it comes out of the cap, as it idles.
The radiator cap can be tested. Most auto parts stores have radiator cap tester that you can use to check for pressure leak.

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Friday, January 21st, 2022 AT 10:14 AM

JASONTYE

MEMBER
3 POSTS

It appears coming from under the engine.

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Friday, January 21st, 2022 AT 10:24 AM

SQM

MECHANIC
6,383 POSTS

I need you to inspect under the hood. Look close to the fire wall, you will see there are a few coolant bypass hoses at the back of the engine. It could be from one of those.