after 30 miles the temp gauge goes up to H?

1996 SUBARU LEGACY
120,000 MILES • 4 CYL • 4WD • AUTOMATIC
Avatar
JOYCE HILL
  • MEMBER
  • 1 POST
Engine was just rebuilt. On highway (never exceeding 70MPH) after 30 miles the temp guage goes up to H. When engine cools down it's 2 or 3 cupl low on anti freeze. I've checked and can find no leaks.
Jun 9, 2010 at 1:07 PM
Advertisement
Avatar
SQM
  • CAR REPAIR CONTRIBUTOR
  • 6,383 POSTS
Hello,

Having low coolant can surely make the engine run hot or overheat.
So, what happened after you added coolant? Did it overheat again or lose coolant?

It is possible that there was air trapped in the cooling system and it appeared to be full initially but as you are driving the correct coolant level showed up.

If you do not have any leak and the coolant level stays where it should with no overheating, it was simply low on coolant due to possible air trapped in the system.

You can try to purge the system again. One way to do it is, with the engine cool, remove the overflow cap. Start the engine, then squeeze the radiator hoses (be careful of any moving components) several times. This will let out any air that could be trapped. If the coolant level stays constant and no bubbles out of the coolant, then it is likely that air is out of the system.

If the engine still overheats with the coolant being full, it could be due to a stuck closed thermostat among other things like the radiator or the water pump.

https://www.2carpros.com/articles/symptoms-of-an-overheating-engine

Please let me know if you have any questions.
Thank you.
Dec 18, 2021 at 7:29 PM
Repair Safety Notice: This information is for general instructional purposes only. Vehicle repair can be dangerous. Verify all information, follow manufacturer service procedures, use proper tools and safety equipment, and consult a qualified repair shop when needed.