Diagnosing Coolant Smells and Leaks in Your Car, SUV, or Truck

by parker
YouTube video

Are you noticing the smell of antifreeze in your car? It could be a sign of coolant leaks, which can lead to running issues and overheating. In this article, we will discuss how to diagnose coolant smells and leaks in your vehicle so you can address the issue promptly and prevent further damage. We will cover step-by-step procedures to identify the problem areas and provide expert tips for fixing them.

Checking the Freeze Point of Your Coolant

One of the first things you should do when diagnosing coolant smells and leaks is to check the freeze point of your coolant. To do this, you can use a refractometer, a tool that measures the amount of ethylene glycol in the coolant. Ensuring that your coolant won’t freeze up in colder temperatures is crucial for the proper functioning of your vehicle.

When using a refractometer, look for the ethylene glycol gauge, usually located on the right-hand side. The gauge should read just below negative 40 to ensure optimal freeze point protection. If the gauge reads zero or worse, it indicates a need to flush out the coolant system.

Testing for Coolant Leaks

To test for coolant leaks, you will need a pressure tester, a tool designed to identify leaks in the cooling system. Begin by attaching the pressure tester to the radiator cap, making sure it is securely locked. Then, pump the pressure tester to at least 15 pounds, or up to 20 pounds, and let it sit for 15-20 minutes.

If the gauge shows a significant drop in pressure during this time, it indicates a coolant leak. However, if the pressure remains relatively stable, you need to investigate other potential causes for the coolant loss.

Checking the Radiator Cap

Another critical component to inspect is the radiator cap. Ensure that the rubber on the cap is not torn or worn. A damaged radiator cap can cause coolant leaks, and it needs to be replaced if it does not hold pressure.

To test the radiator cap, use a tester with an adapter that attaches to the cap. Pump the tester until it reaches the cap’s pressure relief point. It should hold pressure all the way up to the specified limit, usually around 18 pounds. If it fails to do so, it indicates a faulty cap that requires replacement.

Identifying Other Potential Leak Sources

Aside from the radiator and radiator hoses, coolant leaks can occur in other areas of your vehicle. Examples of potential leak sources include:

  1. Radiator Hoses: Inspect the upper and lower radiator hoses for any signs of leakage. Pay attention to where they connect to the engine or radiator. Any drips or visible moisture may indicate a leak.
  2. Water Pump: Check the water pump for any fluid coming down from it. The lower hose connection is a common area for potential leaks.
  3. Heater Core Hoses: Follow the heater core hoses and look for any signs of leakage along the firewall. Dripping coolant could indicate a leak in the heater core hoses.
  4. Head Gasket or Intake: Although rare, a faulty head gasket or intake can also cause coolant leaks. If you suspect these components, it is advisable to consult a professional mechanic.

Diagnosing a Bad Head Gasket

While diagnosing coolant smells and leaks, it’s essential to pay attention to the exhaust tailpipe. Have someone start the vehicle while you observe the tailpipe for any smoke. White smoke billowing out of the tailpipe is a clear sign of a bad head gasket.

Summary of Findings and Recommended Fixes

After thoroughly testing your cooling system and inspecting potential leak sources, you can conclude your diagnosis and plan the necessary repairs. In the example mentioned earlier, the radiator cap was identified as the source of pressure loss. Additionally, a slight leak was found in the petcock, which needed replacement. By fixing these issues and ensuring a proper seal, the coolant level can be maintained, preventing running issues and potential overheating.

Remember to road test your vehicle after making any repairs to ensure that the coolant system is functioning correctly.


Diagnosing coolant smells and leaks is crucial for maintaining the health of your vehicle. By following the step-by-step procedures outlined in this article, you can identify the problem areas and take the appropriate measures to fix them. Regular maintenance and prompt action will help you avoid expensive repairs and keep your car, SUV, or truck in optimal condition for years to come.

For high-quality auto parts, visit 1aauto.com. They offer a wide selection of parts that can be conveniently delivered to your door. Subscribe to their YouTube channel for more useful repair tips and secrets that only mechanics know.

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