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Toyota Corolla Radiator Problem

Your Toyota Corolla’s engine should always remain at the correct temperature when you’re driving, about halfway between C and H. But if it gets closer to the H level, there might be a radiator problem to blame.

A Toyota Corolla radiator problem is a relatively simple fix. Typical solutions include adding more coolant, using a stop leak product, replacing some parts such as the temperature sensor, or flushing a clogged radiator.

Hand opening radiator cap

How do you diagnose and troubleshoot radiator problems in your Toyota Corolla? Read on and learn how easy it is to get your car back to good running condition and take away the risk of overheating.

How To Flush the Radiator Toyota Corolla

Car radiator

When repairing leaks or replacing parts when you have a Toyota Corolla radiator problem, you might need to flush the radiator. Flushing the radiator will also help protect your engine and make it run smoother.

How do you do this? Follow the steps below:

  1. Be sure that your Toyota engine is completely cool, and then pop off the radiator cap.
  2. Put a drain pan underneath where the radiator is.
  3. Loosen the petcock valve by turning it a bit until it opens.
  4. The radiator fluid will start draining.
  5. Take out the radiator fluid reservoir and clean it out with water.
  6. Rinse out the radiator and close the petcock valve shut.

If you have an especially dirty coolant, you might want to get something like the Prestone AF-Kit Flush ‘N Fill Kit that can help get rid of the muck.

Toyota Corolla Radiator Leak

Hand working on car radiator

Your Toyota Corolla has a cooling system that circulates antifreeze throughout the engine, including the radiator, thermostat, water pump, hoses, and other parts. The thing with radiator leaks is that they’re pretty easy to detect: if you let your car idle for some time, you’ll see a puddle right under where your radiator is.

However, be careful not to confuse it with leaks from other components, such as the water pump, thermostat housing, or hose. If these are the parts leaking, the puddle would most likely appear under the engine.

Another telltale sign of a leaking radiator is when your car overheats. So be sure to monitor your coolant level and temperature gauge to avoid overheating.

Another symptom of a radiator leak is a squealing belt. The leak could spill coolant onto the belt, which can slow down the accessories of your engine. There’s also the white smoke that can come from under the hood, even if the car isn’t overheating. This white smoke stems from the coolant that gets into the exhaust or the hot engine.

How To Fix a Toyota Corolla Radiator Leak

For smaller leaks, there are stop leak products that you can use. Products like these are made with aluminum or other pliable materials that can help close the leak:

  • Prestone Radiator Sealer Stop Leak
  • Bar’s Leaks Block Seal Liquid Copper Intake and Radiator Stop Leak
  • K-Seal Multi-Purpose Leak Repair

Toyota Corolla Radiator Hose Replacement

Person working on car engine

If the leak is too big or is located on the radiator hose, it’s time to replace the hose. A radiator hose can wear out for two reasons: time or oil leaks. These situations could make the hose swell or crack.

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Driving with a leaking radiator hose can easily lead to overheating. You can buy a replacement radiator hose, such as the Dayco Radiator Hose, for less than $25. Meanwhile, an OEM version, such as the Genuine Toyota Radiator Hose, is similarly inexpensive.

Toyota Corolla Radiator Fan Not Working

Car radiator fan

The radiator fan helps keep your engine cooler, even when it’s been running for a long time. When it stops working, it might lead to your car overheating or running into problems when the radiator isn’t working correctly. How do you know if the radiator fan isn’t working?

  • When the AC is on at the second setting, you can see that at least one of the fans isn’t spinning.
  • When the car has been running for a while with the AC off, even when the engine is hot enough, at least one of the fans isn’t running.

There are a few reasons why your radiator fan isn’t working as it should. Locating the problem is key to solving it.

Electrical Problems

Check the fuse of your Toyota Corolla’s radiator fan. If it’s blown, replace it. But you have to locate the fuses first because they could be in a different place, depending on your Toyota Corolla’s model.

Checking the Cooling Fan Temperature Switch

The location of this switch varies depending on your Toyota Corolla model year, so be sure to check your user manual to find out where it is.

Using a test light such as this OctagonStar Circuit Tester, you can check on the temperature switch. Connect the test light to the battery ground and then start your engine. Let it idle and back probe the connector terminals of the switch using the test light.

One of these terminals will trigger the light. Wait for the engine to get to operating temperature and then back probe the other wire that didn’t light up.

If the other terminal didn’t trigger the test light, then the switch is faulty.

Checking for Short Circuits

When the fans blow out the fuses regularly, then there might be a short circuit between the fan and the relay.

Checking the Coolant Temperature Sensor

There are five symptoms of a faulty temperature sensor. These are:

  • Overheating
  • Poor idling or hard starting
  • Poor fuel mileage
  • Emits black smoke
  • The Check Engine light comes on

Depending on the year model of your Toyota Corolla, the location of the engine temp sensor will vary. But the thing is, replacement sensors such as the following products don’t cost much and are easy to replace:

  • Hoypeyfiy Engine Coolant Temperature Sensor
  • YCT Engine Water Coolant Temperature Sensor
  • OTUAYAUTO Engine Coolant Temperature Sensor

Replacing the Cooling Fan or Motor

Sometimes, it’s a problem with the cooling fan assembly, and that’s best remedied by replacing the cooling fan. Here are a few options:

  • Automotive Cooling Inc Radiator And Condenser Fan
  • JP Auto Engine Cooling Fan Motor
  • TYC Replacement Cooling Fan Assembly

Toyota Corolla Radiator Fan Stays On

Person working on car engine

Your radiator fan should only turn on when the engine gets hot enough. So there’s a problem when the fan starts running the moment you turn the engine on or while it’s still cold.

There are several possible culprits behind this: a broken temperature sensor or a faulty relay. First, check the relay by swapping out the fan relay with another one you can find in your Corolla’s engine.

Or, you can just buy something like the Aotop Coolant Fan Relay and put it into the slot where the old one is.

If that doesn’t solve the problem, check the temperature sensor.

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KnowMyAuto is the sole owner of this article was published on May 20, 2021 and last updated on .

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