6 Common Bad Radiator Symptoms You Most Know

bad radiator symptoms

Bad radiator symptoms you should look out includes overheating coolant loose and more. The radiator is a component of the cooling system that transfers heat from coolant to outside.

The Radiator houses valves and passage ways through which coolants flow. These action of the radiator thereby helps to regulate the engine’s temperature and preventing it from overheating.

Radiators are also often used to cool automatic transmission fluids, air conditioner refrigerant, intake air, and sometimes to cool motor oil or power steering fluid. When the radiator is blocked the engine is said to overheat.

Major Cause of Overheating


Over heating being the first sign of a bad radiator is just the beginning and could cause even blown head gasket if not taken cared of in due time. Below are the basic seven bad radiator symptoms you should look out for

  • Broken or thermostat failure

The primary work of the thermostat is regulation and monitoring the temperature of the coolant in the engine. It also ensure flow of coolant through the engine in the right proportion and needed areas.

The thermostat is necessary and an important component of the car cooling system. Whenever the coolant gets hot the thermostat opens allowing coolant to flow through to the radiator to be cooled.

A temperature gun is needed to determine how efficient a thermostat is. To test for thermostat efficiency, follow the steps below

  1. Start your car and warm up the engine for 15 minutes.
  2. Scan the top and lower radiator hoses with infrared gun for temperature reading.
  3. Wait for about 5 minutes to get a heat reading.
  4. If both hoses stay cold or one becomes hot its a symptoms of a bad thermostat.

If you notice overheating temperature in the coolant allow the engine to cool down for about an hour before attempting to open the radiator hoses. You can easily fix this by flushing the radiator with a garden hose.

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If there is any clog or dirt stopping the normal flow of coolant through the cooling system it is worth giving quick attention. An internal radiator is clog is the least that can happen to when coolant is have not been changed in a long time.

Coolants starts to show elements and sign of rust finally gets clogged if the coolant is not replaced on time. The walls of the radiator too may start to show some signs of rusting thereby clogging the radiator.

Radiator clog could be internal and external, if your radiator has an internal clog, the coolant flow is restricted. On the other hand, the external clog cause the airflow to become restricted and lead to overheating. Here’s what you need to do to check:

  1. Off the car and allow the engine to totally cool off
  2. Open the radiator pressure cover
  3. Have look inside the radiator and check for clogs and any form of dirt
  4. If you notice any of dirty or clog you might need a radiator flush or replacement.
  5. Examine the outer part of the radiator for any visible clog
  6. Clean the exterior by flushing it with garden hose

An overheating engine is a symptoms of clogged radiator. If you have an external clog in your radiator, it might cause the airflow to become restricted and lead to overheating.

  • Leaking Cooling system

If there’s a leak in the cooling system, your engine will overheat. You must repair this immediately if you want to prevent further damage. To perform this check, you’ll need a cooling system pressure tester and coolant dye kit.

  1. Cool the engine completely.
  2. Take off the pressure cap and set it somewhere safe.
  3. Follow the manufacturer’s instructions and apply pressure with your tester.
  4. Examine the system for a leak.
  5. If you need to, add some coolant dye after removing your tester.
  6. Put your radiator cap back on and start your engine.
  7. Watch for a leak by keeping an eye open for the dye.
  • A loose radiator cap cover

Yes loose radiator cap is not a good thing for the cooling system. A loose radiator cap is another bad radiator symptom you should always look out for.

When the radiator cap is loose it will not hold pressure causing the coolant to overheat and boil. Failure of the radiator to hole pressure will in turn lead to the engine overheating. To check for radiator cap lost of pressure, do as follows

  • Allow the engine to cool off for an hour
  • Unscrew the pressure cap and remove it
  • Replace the radiator with the pressure tester
  • Ensure that the pressure tester is attached the right way
  • Bad water pump

A broken water pump will cause inefficient flow and circulation of coolant through the cooling system. Endeavor to check the thermostat for any form of malfunctioning signs before checking the water pump.

The process of checking the water is also easy and straight forward. To check for a bad or malfunctioning thermostat follow the guide below

  1. Cool the engine completely.
  2. Take off the pressure cap.
  3. Start the engine and watch the coolant to see if it begins circulating.
  4. If it doesn’t move, you could need a water pump.
  5. Look at the water pump. It might have signs of a leak.
  6. Look for wet spots or dry green or white residue.

This 5 mentioned points are the major bad radiator symptoms you should look out for to avoid and overheating engine. If you have any more questions please endeavor to use the comment box to ask us.

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