[Petertay]

BACKGROUND: Cool day, 65 degrees. Driving on Interstate at 70 mph. The engine overheat light came on.

Lifting the hood, we see antifreeze moisture was blown around the engine compartment, but the radiator was not boiling over. The coolant resovoir had the right amount, neither high not low. Took the radiator cap off and, of course, didn't see any liquid. The upper and lower hoses seemed in good shape tightly clamped. Got towed off the tollway.

I added 1/2 gallon water directly into the radiator with engine running, to see where it might be leaking. Engine ran for 20 minutes--no drips or leaks, no overheat, but the cooling fans did not run either. Turned on the AC and the fans started up, so apparently they work.

Drove home, two hour drive. No problems, though it did take a few cups of water when trip was done.

QUESTION: What might have gone wrong to cause coolant lose and overheat? What do we need to do to avoid future problems? Thanks for replies.

 

[adc]

Since you did not list a profile we don't know what year/engine you have..makes a difference.
I personally don't answer any questions unless the person gives a profile..that's just me.

 

[Easy Fixer]

won't hold pressure

Your system isn't holding pressure. I disagree the system is boiling over. Pressure check the system and find out where it's losing pressure.

 

[Theseus161]

You may need a new radiator cap. The spring can loose tension after a while. I just replaced mine after 66k miles.

 

[Petertay]

We pressure tested the radiator and it holds pressure. What could it be? Maybe the thermostat. Since I have to drain the radiator anyway to put in new coolant, I’ll put in a new thermostat.

 

[adc]

Use a subaru Tstat

 

[Easy Fixer]

radiator

A partially clogged radiator will cause these problem. Next time the radiator get warm feel for hot and cold spots on the radiator. Or replace will a new radiator.

 

[Petertay]

Thank you for the replies and suggestions. Much appreciated. We ordered the Subaru thermostat, and will check the radiator more closely when we put it in.