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Engine Head Gasket Repair

Dan Ferrell writes about DIY car maintenance and repair. He has certifications in Automation and Control Technology and Technical Writing.

Head Gasket Repair: Be Prepared

Engine head gasket repair is an expensive job. However, car owners with some mechanical experience, or those willing to take the time to learn, can save a lot of money.

What you need for a successful gasket repair

  • Access to required tools for the job
  • Time for the project
  • Suitable space to work on the project
  • Good organizational skills
  • Repair manual for your particular vehicle model

Of course, these factors may depend on your experience working on cars, how motivated you are for the project, and the engine model you need to work on. Some vehicle models are much easier to work on than others.

How much do you need to invest?

At a repair shop, replacing the head gasket could run over $2000.00 depending on vehicle model and type of repair.

Engine head gasket

$38.00 to $50.00

Related components (gaskets, water pump, timing belt, thermostat, valve kits, oils, antifreeze)

$200.00 to $500.00

Engine block or head service

$200.00 to $2000.00

Before You Start

Before you start, it is important to:

  • Have a good diagnosis of the problem.
  • Know the state of "health" of your engine.
  • Evaluate alternatives: a new head, a new or rebuilt engine, a used or new car.

Note that if the engine head gasket has failed due to overheating or detonation, the chances of the engine block or cylinder head being damaged increases. But you won't know this until you disassemble the engine and, possibly, have it inspected.

If you are dealing with a small head gasket leak, head or block crack, you may want to try a sealer first. K-Seal is a good product and is easy to use.

Usually, after the first 20 minutes, you'll know whether the product will work in your engine. Make sure to read the instructions carefully.

If you are dealing with a coolant leak into a combustion chamber, remove the spark plug and disable the fuel injector before using the product to relieve some of the pressure during the repair.

Head Gasket Home Repair

  1. Can You Replace the Engine Head Gasket at Home?
  2. Before You Begin
  3. Disassembling the Engine
  4. Removing the Cylinder Head
  5. After Removing the Cylinder Head
  6. What You Need to Know When Installing a New Head Gasket
  7. Resources

1. Can You Replace the Engine Head Gasket at Home?

On some engines, replacing the head gasket is relatively easy; on others it's a challenge. As mentioned earlier, replacing the head gasket successfully depends on the engine you need to work on, your experience, and the tools you may need access to for your particular model.

Still, such a project is possible for the DIYer following a few recommendations:

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  • Find out in advance what the project entails by consulting the repair manual for your specific car model.
  • Make sure you have the necessary tools.
  • Get in touch with someone who has more experience and is willing to offer some advice. For this purpose, you can visit a forum where car technicians or DIYers meet to discuss their own projects. They might be able to guide you before you start and during the project.
  • Implement a good method of organization that works for you.

Start your project by going through the following sections. They give you important information for the project.

Go through the repair manual for your vehicle model as well. If you don't have one yet, you can get a relatively inexpensive copy through Amazon.

Haynes manuals include:

  • Step-by-step procedures
  • Images and photos
  • Location of components
  • Description of the different systems
  • Diagnostics
  • Torque specifications
  • Maintenance program

Besides guiding you to replace the head gasket, the manual helps you carry out many maintenance, mechanical, and diagnostic tasks that will allow you to recover the small investment in a short time.

2. Before You Begin

Aside from having the necessary tools and the corresponding repair manual for your specific vehicle model, make sure your local auto parts store, or online stores, have the parts you need for your model.

Some of the parts you may need for this project:

  • Head gasket kit
  • New engine oil
  • Antifreeze
  • Spark plugs
  • Timing belt or chain kit
  • Cover gasket
  • Intake manifold gasket
  • Exhaust manifold gasket
  • New cooling system thermostat
  • Water pump
  • Drive belt
  • Valve train kit

Check your car's manual for a complete list of tools and components you'll need for the project.

When buying parts for your vehicle, it's a good idea to use the vehicle identification number (VIN) to make sure you're buying components for your specific model. Engine designs change from year to year.

3. Disassembling the Engine

The success of the project can be determined by where and how to work, especially if you don't have much experience.

Here are some suggestions:

  • If possible, work in an enclosed garage or porch where you can isolate the engine and critical components from dust and debris.

    It is important that an engine, ready to be assembled, doesn't become contaminated with dust and other coarse particles that may scratch internal surfaces once it is assembled. This could result in leaks and affect engine performance later.

  • Follow the suggestions in your vehicle repair manual for engine disassembly. Make a list of the main tasks you need to do and the tools you will need. This list can serve as a general guide during the project. A list can serve as an excellent organization tool to work on a cylinder head buried under a bunch o components you need to remove to gain access.
  • Disconnect the battery and drain the oil and antifreeze from the engine and radiator. Store them in a safe container for later recycling.
  • Work in an organized way. Arrange the parts that you are removing from the engine on a shelf or safe area in the order in which you remove them, along with screws, nuts, pins and any other parts related to each component. This will speed up the reassembling process.
  • To adjust the timing chain, some vehicle models use oil pressure, and you must follow a specific procedure to work on it. Follow the instructions in your repair manual.
  • Your repair manual tells you the sequence and torque you need to apply to remove the camshaft(s) and cylinder head screws. See the next section.
  • Sometimes, it's a good idea to leave the intake and exhaust manifolds installed until you are ready to remove the head. You can use the manifolds as a lever to gently separate the head from the block once you've removed the head screws. Do not use screwdrivers or wedges to separate the head from the block, this could damage the head or block gasket surface.

4. Removing the Cylinder Head

According to your repair manual, installing or removing the cylinder head bolts has to follow a pre-determined sequence and torque.

  1. The head bolts are installed to a certain torque specification, such as 46 lb-ft (pound-feet). The bolts have to be removed in three or more passes, decreasing the degree of torque during each phase.
  2. Start with the bolts located on the outside of the cylinder head until you reach the bolts in the center. Your repair manual will tell you the correct sequence.

    The bolts toward the outside of the head have to be loosened first to prevent distorting the head. Distortion may occur when the center bolts are loosened first, especially on a head that has suffered overheating.

  3. Mark each head bolt so you know its exact location on the head. Install new head bolts and use the old ones as a guide. Many cylinder heads mix bolts of different sizes and must be installed in the correct location.
  4. Once you remove the head bolts, you can use the intake or exhaust manifold as leverage to gently separate the head off the block if necessary. Lift the cylinder head straight up first, so that it clears the mounting dowels. Don't use a screwdriver or similar tool to force off the head. You may damage the head or block.
  5. Place the cylinder head on wooden blocks.
  6. Take the cylinder head, and the block if necessary, to a machine shop for cleaning and inspection. If overheated, the head may need to be resurfaced.

5. After Removing the Cylinder Head

After removal, the cylinder head needs to be serviced.

  • Remove pieces of old gasket stuck to the surface of the head using a plastic putty knife or card, like an old credit card or something similar. This prevents scratching or damaging the surface of the head.
  • To remove burrs and other deposits from the gasket surface use special chemicals. You can buy them at your local auto parts store. Avoid using abrasives, especially with drills, which could leave slight indentations on the gasket surface and prevent the correct seal of the cylinder head or block.
  • If the gasket failed due to overheating or detonations, send the cylinder head and block to the machine shop for inspection and cleaning. The head or block may be cracked, warped, distorted, or crooked.
  • Before installation, the head should be completely clean, including the threads in the screw holes. This ensures the correct amount of torque is applied during the assembly process.
  • Likewise, if your engine uses an overhead camshaft, the centerline of the bearing supports may need to be refaced.
  • On a V-type engine, if the head was resurfaced, the intake manifold gasket surface area might have to be refaced as well. This is done to maintain proper mating between the manifold holes and the bolt holes in the head.
  • Consider replacing other key components such as the water pump, engine belt, timing belt, valves and related accessories. This will increase head gasket service life and improve overall engine performance.

6. What You Need to Know When Installing a New Head Gasket

Here are some tips you need to know when installing a new head gasket.

  • After sending the engine head, and possibly the block as well, for inspection and repair, the tool shop may suggest a different type of gasket than the one recommended by the automaker. This might be necessary to compensate for a head that has been polished or grounded. Follow the workshop recommendations.
  • On many V-type engines, the heads are interchangeable, but not all. Be sure to install the correct gasket for each head. On the head gasket, match the holes for the coolant and oil with those on the block and cylinder head. In a gasket, however, the coolant holes are much smaller in order to control the rate of flow, so don't be confused by this.
  • The new head gasket may come with a sheet of instructions. These may help you prepare the engine block and head for installation, tips for a better seal, and some spots on the head and block that may require special attention.
  • Tighten the head bolts in three or more steps using a torque wrench, depending on the engine model. This will help the gasket compress and conform to the block and head surfaces. Consult your vehicle repair manual.
  • Your repair manual lists the head bolt's torque specifications and the correct sequence. Remember that the screws and threads have to be completely clean so that the torque can be applied correctly to each screw. And use only the specified lubricant for the head screws. For example, if the instructions in the manual call for SAE 40 motor oil, don't use 15W-40. Using the wrong grade of lubricant can affect the clamping force applied to the head gasket.
  • After installing the cylinder head, install the timing belt or chain. Refer to the repair manual. Also, check the article included in the Resources section at the end of this post.
  • If you are replacing the head gasket for a reason other than wear or corrosion, discover the source of the problem. If the gasket failed due to overheating or detonation, diagnose the problem and fix it; otherwise, the new gasket could fail.

After installing all engine accessories and flushing the cooling system, add a sealant to the new coolant and make sure there are no air pockets left in the system to prevent overheating. Bleed the cooling system following the instructions in your repair manual.

Also, take a look at the article How to Change Coolant Without Causing the Engine to Overheat listed in the Resources section at the end of this post.

Resources

This article is accurate and true to the best of the author’s knowledge. Content is for informational or entertainment purposes only and does not substitute for personal counsel or professional advice in business, financial, legal, or technical matters.

© 2022 Dan Ferrell

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