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How to Troubleshoot the Cooling System in Vehicles

by Contributing Writer; Updated June 12, 2017

Before you start troubleshooting your Vehicles cooling system, take a moment to clean the front of your radiator with a hose, soap and brush. The tubes inside the radiator can easily become clogged with dirt, which prevents antifreeze from circulating properly. If this doesn't immediately correct your problem, you can check your system with a few simple steps.

Under The Hood:

 How to Troubleshoot the Cooling System in a Honda Accord

Check for Overloading or Leaks

Park your can in a safe and level location. If you have a manual transmission, put your car in "Neutral." If you have an automatic, transmission put the car into "Park." Apply the parking break.

Look for steam or smoke coming from under the hood. If you see steam or smoke, turn off the engine and wait until the steam and smoke stops, before turning the engine on again. If you don't see steam or smoke, keep the engine running.

Locate your temperature gauge and watch it to see if the engine starts to cool. Your engine should cool if the overheating is due to overloading. If then engine cools to the midpoint of the gauge, it is safe to drive the car again.

Turn the engine off if the temperature gauge stays in the red area, indicating overheating.

Examine the engine for coolant leaks. Look for a split in the radiator hose. If you find coolant leaks, take your car in for service. Move onto checking the coolant level if you don't find leaks.

Examine the Coolant Level

Check the coolant levels in the radiator reserve tank. Add coolant if your coolant level is below the "min" mark.

Add coolant to the radiator if the radiator reserve tank is completely empty. To do this, allow the engine to cool, then use gloves and turn the radiator cap in a counterclockwise direction, without pushing down.

Stop turning the cap when you start to hear hissing. After the hissing stops and the pressure has released, push down and continue turning the cap.

Remove the cap completely and start your car's engine. Set the car's temperature to maximum heat.

Pour coolant into the radiator until the coolant reaches the base of the filler neck. Put the radiator cap back on and start the engine.

Allow the car to run for a few minutes. Watch the temperature gauge. Once the gauge starts to indicate cooling, check the radiator reserve tank one more time. If the coolant level is low, add coolant to the "max" mark.

 How to Troubleshoot the Cooling System in a Chevy Impala

Check the Coolant Level in the Coolant Recovery Tank

Park your Impala on a level surface.

Find the coolant recovery tank, located in the back of the engine compartment on the passenger side.

Look at the coolant recovery tank, to see if the coolant is boiling. If it is boiling, wait and allow it to cool before moving forward.

Verify the coolant level is at or above the word "cold," located on the side of the coolant recovery tank facing the engine.

Add a coolant mixture to your coolant recovery tank if the coolant level has dipped below the "cold" mark.

Add Coolant to the Radiator

Start your Impala after you've checked and filled the coolant recovery tank.

Look to see if the you're still getting the overheat warning. If it's still there, locate your radiator pressure cap, which is towards the front of your engine compartment on the passenger side.

Turn the radiator pressure cap slowly in a counterclockwise direction. Stop turning it if you hear a hiss. Once the hiss stops, turn it again as you push down on the cap. Open the coolant air bleed valves.

Pour a 50/50 water and DEX-COOL mixture into the radiator. Leave the radiator pressure cap off. Close the bleed valves and clean up any coolant that may have spilled.

Fill the coolant recovery tank to the "cold" mark, if necessary, and put the cap back on the tank.

Start your engine and allow it to run until the upper radiator hose is hot to the touch. Replace the radiator pressure cap.

Look at your coolant recovery tank again. If the engine is hot, the coolant level should be at the "hot" mark. If the engine is cool, then it should be at the "cold" mark.

 How to Troubleshoot the Cooling System in a Ford Explorer

Find your Explorer's coolant reservoir under the hood on the passenger's side in front of the engine filler. Check the levels. There's a "MIN" mark on the outside of the coolant reservoir. If the levels are low, add a 50/50 mix of coolant and water.

Run the engine for a few minutes or until its warm then turn the engine off to test whether your thermostat is stuck open. Open your Taurus' hood and locate the two radiator hoses. The hoses are black, made of rubber and connected to the radiator. Touch the top hose and notice if it feels hot. Look for the bottom radiator hose connected to the bottom of the radiator. Touch this hose and notice if it's cold or warmer than the top hose. If your thermostat is working correctly, the bottom hose will be warmer than the top one. If you notice that one hose is significantly hotter than the other, your thermostat is most likely stuck open. If this is the case, you'll need to replace the thermostat.

Look at the radiator cap's condition when the engine is cool. The radiator cap seems like a simple thing, but its condition is crucial to your Explorer's cooling system. A faulty or damaged cap can cause engine overheating.

Check the radiator hoses for cracks and holes. If the hoses are in bad condition, your coolant can leak and lead to the engine overheating.

Take your Explorer to a mechanic to inspect the radiator core. It takes a trained professional to remove the radiator and check for corrosion. Another problem your mechanic can look for is a plugged core. If you notice that the Explorer's engine runs hot while driving at high speeds, this may be the problem.

Listen for your car's cooling fan. The car's fan comes on when the coolant's temperature rises to a certain point. This is an easy step to troubleshoot. Drive your car for 1 to 20 minutes. Park the car and open the hood and keep the engine running. You'll be able to hear the cooling fan. If you don't hear it, that means it's not working and it needs to be replaced.

Items you will need

  • Cleaning brush

  • Garden hose

  • Engine coolant

About the Author

This article was written by the It Still Runs team, copy edited and fact checked through a multi-point auditing system, in efforts to ensure our readers only receive the best information. To submit your questions or ideas, or to simply learn more about It Still Runs, contact us.

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