How to Clean an Engine After a Blown Head Gasket

by Melissa MorangUpdated July 06, 2023
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Maintaining a car requires effort. Certain things will happen over time on any vehicle. However, doing your own repairs and maintenance can save a lot of money, such as fixing a blown head gasket. But after the repair you must take special care to clean the engine thoroughly. The blown head gasket will most likely contaminate the engine oil with engine coolant and vice versa. Cleaning the engine is simple and will ensure a well-functioning system.

Things You'll Need:

  • Oil filter
  • Oil
  • Coolant system flush
  • Engine coolant
  • Catch basin

1. Run the engine for one to two minutes

Run the engine for one to two minutes. This must be done after the head gasket repair. Basically, this allows the oil to circulate and pick up any particles or dirt that may have entered the engine while it was open for the head gasket replacement. The circulation of the oil brings any foreign matter or dirt into the oil filter or oil pan.

2. Change the engine oil and the oil filter

Change the engine oil and the oil filter. The oil and filter are contaminated with dirt and foreign matter, and even engine coolant. So, the old oil must be drained from the engine completely. Place the catch basin under the engine and remove the engine oil drain plug located in the oil pan on the bottom of the engine.

3. Replace the oil filter and replace the oil drain plug

Replace the oil filter and replace the oil drain plug after all the old oil has drained. Refill with fresh clean oil.

4. Drain engine coolant

Drain engine coolant. Since the coolant can also be contaminated with engine oil, it must be replaced. Drain out coolant by removing the radiator cap and the lower radiator hose connection from the radiator. Make sure the catch basin is underneath the open radiator hose to catch the coolant. After drainage, reconnect the radiator hose.

5. Refill the radiator with coolant system flush

Refill the radiator with coolant system flush, which can be purchased at most auto parts stores. Another option is to use a mixture of coolant and water at approximately 50 percent each. Replace the radiator cap.

6. Circulate the coolant or coolant system flush

Circulate the coolant or coolant system flush. This is accomplished by starting the engine and running until it is up to operating temperature. This typically takes about 10 minutes. Allow to run for another five to 10 minutes after the engine has reached operating temperature.

7. Drain the coolant system

Drain the coolant system. This is accomplished by first turning off the engine and allowing it to completely cool before attempting to open the radiator cap or radiator hose. The radiator cap should be cool to the touch. Remove the radiator cap and the lower radiator hose connection at the radiator side. Allow the cooling system to drain completely into the catch basin. Reconnect the lower radiator hose.

8. Refill the engine coolant system completely

Refill the engine coolant system completely. To accomplish this, pour coolant into the radiator until full. Leaving the radiator cap off, start the engine and allow it to run until you see circulation of the coolant in the radiator. Turn the engine off. In most cases, you will see the level in the radiator drop. This happens because the running of the engine removes air pockets, thus lowering the level. Add more coolant and replace the radiator cap.

9. Clean the engine compartment

Clean the engine compartment by spraying an engine degreaser on the exterior portion of the engine. Also, spray the degreaser on the radiator and any components that may have become contaminated with engine oil or coolant. Spray degreaser on the warm engine. Let it sit for approximately five minutes. Then start the engine and allow iit to run while spraying the engine with water to clean the residue of the degreaser. Run the engine for an additional five minutes. This will ensure everything is dried.

Tips and Warnings

Run the engine while spraying with water to keep the electronic connections from shorting out.

Make sure the system is completely cool before opening the radiator. A hot radiator can cause severe burns. Make sure to catch both the engine oil and the coolant in a catch basin. Oil and coolant are dangerous to the environment, pets, wildlife and even humans. Dispose of properly.

Video showing how to clean an engine after a blown head gasket:

Comments on this video:

  • Sometimes there's just no substituting a pressure washer for those hard top get to areas on the mating surfaces of the engine/transmission.
  • So grateful to finally see this video! Thanks so much! Also, would this technique work on exhaust pipes as well? How about cleaning the underside of a car in general? Keep up the good work!

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