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 1,000 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!
  1. Home
  2. Questions
  3. Over heating coolant not siphoning back into coolant over flow tank

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: Front car window stuck

Hi there. Although your window motor is engaging your window maybe of its track. This mean that the "guide" that it follows is no longer directing the window the correct direction. This leads to the window making a clicking noise...

Q: Silhouette

Many different parts can cause the vehicle to overheat. The most common would be the thermostat, radiator, water pump, air in the coolant, or a coolant leak. When a vehicle overheats at idle the usual suspect is the radiator fans....

Q: How do I handle this car issue?

Hi Ashley. Thanks for contacting us today. This is a very good question and one that often confuses car owners as to the proper way in which to handle. The solution really depends on what type of warranty or coverage...

Related articles

P0240 OBD-II Trouble Code: Turbocharger Boost Sensor B Circuit Range/Performance
P0240 code definition Turbocharger Boost Sensor B Circuit Range/Performance What the P0240 code means P0240 is an OBD-II generic code triggered when the Engine Control Module (ECM) detects the intake boost...
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...
P2428 OBD-II Trouble Code: Exhaust Gas Temperature Too High Bank 1
P2428 code definition A P2428 trouble code signifies that the PCM has detected a problem in the exhaust gas temperature sensor circuit in bank 1, which subsequently contains the number one...