How to Repair a Head Gasket

Written by april kohl
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How to Repair a Head Gasket
Cracked head gaskets can be repaired temporarily with block sealant. (Jupiterimages/ Images)

Engine trouble is any motorist's worst nightmare and a damaged head gasket is no exception. Because of its central role in the engine block, a cracked or seal-damaged head gasket often signals an expensive repair bill. Thankfully it is possible to learn how to repair a head gasket yourself, so you can effect a quick temporary repair to keep you motoring while you save up for a replacement part.

Skill level:

Things you need

  • Bowl
  • Pliers
  • Block sealant

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  1. 1

    Check your radiator to find the petcock valve. It is usually on the bottom of the radiator but if you cannot find it, consult your vehicle's owner's manual for instructions. Place the bowl underneath the petcock valve to collect the fluid that will come out. Open the petcock using the pliers and drain the antifreeze from the radiator into the bowl. Dispose of the contents of the bowl safely. Close the petcock valve on your radiator.

  2. 2

    Prepare the block sealant, following the instructions provided for the particular brand of sealant you are using. Open the intake cap on the radiator. Pour the block sealant mixture into the radiator. Close the intake cap. Close the bonnet on your vehicle. Turn on the engine and allow the vehicle to idle for thirty minutes, so the mixture has time to settle into the head gasket.

  3. 3

    Take the vehicle on a long trip, driving aggressively rather than for economy. This will work the block sealant into the cracks and give it time to react; sealing the cracks and repairing the head gasket. Turn off the engine. Pop the bonnet and place the bowl under the petcock valve. Drain the water and leftover sealant from the radiator. Close the petcock valve. Refill the radiator with coolant.

Tips and warnings

  • Make sure that all the coolant has been drained from the radiator before adding the block sealant. There are chemicals in the coolant fluid that will react with the sealant solution, preventing the sealant from setting correctly. As a result, cracks in the head gasket will not plug correctly.
  • Sealing cracks in a head gasket using block sealer is a temporary fix at best and cannot be guaranteed to work in the long term. While block sealer will prolong the life of your head gasket, your best option for a repair on your vehicle is to replace the damaged head gasket as soon as you can.

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