Skip the auto shop - Our mechanics make house calls

Q: Over heating coolant not siphoning back into coolant over flow tank

asked by on

About 2 weeks ago my car started to over heat as i was going on the highway. When i checked my coolant (after i let it cool made it home and let it cool completely) i noticed that the coolant overflow tank was completely empty but the radiator was over filled with coolant. Added more coolant to tank. Couple days later car wad over heating again opened hood and noticed the coolant was spilling out onto the ground because it was being spit outta the overflow port on the cap that goes to the coolant tank. Was told by one mechanic it was my thermostat. Had it replaced yesterday. Today care is still over heating and spitting coolant out of the overflow spout instead of siphoning back into coolant overflow tank.

My car has 250000 miles.
My car has an automatic transmission.

Hey there:

It’s common for many mechanics to make the mistake of mis-diagnosing the cause of an overheating situation; especially when they assume it’s a thermostat issue. The problem could be caused by a blockage in the coolant tubes running from the radiator to the overflow tank and back to the radiator. However, it also may be due to air trapped in the coolant lines. I think a good idea would be to contact a different ASE certified mechanic, such as one from YourMechanic, and have them complete a coolant flush, which should remove any blockages in the coolant tubes and may solve your problem.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: Car cut off on the highway and never started back up.

Hello there, many faults will cause your 2004 Chevrolet Impala to die while running and not restart. The P0443 code is for the Evaporative Emission Control System Purge Control Valve Circuit and though this will need to be addressed will...

Q: Refill of coolent

This is a little odd given the age of the vehicle as it should not be too low on coolant this soon, however there are numerous reasons this may happen. A common problem is a slow leak or potentially some...

Q: Car won't start and only makes a single clicking sound with a brand new battery

You could be right, it may be the starter. But I wouldn't run out and buy a new part yet. It could also be a number of other problems like relays, electrical connections, or even the security system.. Trying to...

Related articles

P0052 OBD-II Trouble Code: HO2S Heater Control Circuit High (Bank 2 Sensor 1)
P0052 code definition HO2S Heater Control Circuit High (Bank 2 Sensor 1) What the...
Rules of the Road For Iowa Drivers
Driving on the roads requires knowledge of the rules, many of which are based on common sense and courtesy. However, even though you know the rules in...
P2103 OBD-II Trouble Code: Throttle Actuator Control Motor Circuit High
P2103 means there is a fault with the throttle actuator control motor circuit, likely due to a defective electrical component or part.