Skip the auto shop - Our mechanics make house calls

Q: Overheats at 120 C even after replacing thermostat and water pump.

asked by on

Overheats at 120 C even after replacing thermostat and water pump, upper and lower radiator hoses still cold. Replaced coolant as well. Car does not get warm inside when the blowing fan is on.
My car has an automatic transmission.

If the hoses are cool, engine coolant is not flowing due to a blockage in passageways or hoses or inadequate water pump speed due to a loose drive belt. If you just added coolant after replacing the water pump and thermostat, but did not use the purge points to expel trapped air, that in itself could be the cause. Trapped air in cooling systems causes overheating because the coolant flow is blocked. Trapped air could also explain why there is no cabin heat as no coolant is flowing to the heater core. If you suspect trapped air, swerving sharply while driving can sometimes dislodge the bubble of air and get it to travel to the top of the radiator where it won’t impede coolant flow. Apart from trapped air, the radiator could be partially plugged. The water pump might not be running at engine speed due to a loose belt.The lower radiator hose could be blocked or partially collapsed. An option for you is to request an overheating diagnostic and the responding certified mechanic will get this diagnosed for you, once and for all. Once the root cause of the overheating is identified, the mechanic will let you know of the required repair.

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: Do you work on Old Mercedes Benz?

It will depend on what kind of work you will be needing. Most maintenance like brakes, filters, belts or most window or body electrical repairs can be done by most mechanics. If you need diesel engine repairs then it will...

Q: Car burning coolant

Hi there. If your car has overheated, it may have caused your head gasket to warp. This warpage allows coolant to enter combustion chambers causing your vehicle to not efficiently cool. An external leak is not necessary for this blown...

Q: Starter turning over without cranking

Hello. Two common component failures that will cause the conditions you've described are a faulty fuel pump relay or a crank position sensor. Both parts have the potential to fail intermittently when they become hot. But when they cool off...

Related articles

What Causes Hoses to Leak?
While the largest part of your engine is mechanical, hydraulics plays a significant role. You’ll find fluids at work in a number of different areas. Your car's fluids include: Engine oil Transmission...
How Long Does a Distributor O Ring Last?
The distributor is part of the ignition system in your vehicle and its purpose is to route high voltage from the ignition coil to the spark plug. The spark plug then...
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.