Engine coolant has many avenues of escape. For the most part, leaks in the cooling system can be confirmed by evidence under the vehicle. Leaks can also be seen on the passenger-side floor if a heater core springs a leak. Loss of coolant that is not evident is usually due to a problem with the radiator, or else the engine is ingesting the coolant into the cylinders because of a head gasket leak.
Things You'll Need
- Coolant system pressure tester
- 3/8-inch ratchet
- Spark plug socket
Remove the radiator cap and check the level of coolant. Check the radiator cap and fluid for a muddy appearance, which suggests that oil has entered the cooling system. Fill the radiator as necessary.
Pull the dipstick and the oil filler cap and inspect both for a muddy appearance. If any oil contamination shows up in this test and in Step 1, then the head gasket has been compromised and must be replaced.
Install the radiator pressure tester and pump it to 17 pounds of pressure. Inspect the undercarriage completely for any leaks. Check the water pump, freeze plugs, hoses, intake manifold, radiator and heater core. If the leak is found, then repair it and re-test. If the leak is not found, then proceed to Step 4.
Remove the spark plugs. Look to for evidence of water contamination. This shows up either as moisture on the plug or a completely clean plug due to the hot water. Have someone turn the engine over, with all the plugs out. Watch for water exiting the holes. Water blowing out of the spark plug holes while the engine is being turned over indicates a blown head gasket.
Tips & Warnings
- Never attempt to open a radiator cap while the engine is hot. The coolant system is under pressure, and hot water will blow up in your face. You will not be able to shut the cap once you start opening it. The pressurized water and antifreeze mixture can reach temperatures of 240 degrees Fahrenheit or higher.
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