Cylinder head repair is a common practice among car owners. It involves various processes, such as welding cracks, machining warps, or fixing failed valves train components. If you are a DIY car repair enthusiast, read on. This article explains the cylinder head refurbishment and resurfacing process in an easy-to-understand way. First, a look at why you would need to fix a cylinder head in the first place.
Why Repair a Cylinder Head?
Reasons for cylinder head reconditioning and resurfacing vary. They include
- Cost savings- the cylinder head repair cost is lower than buying a new head. It saves you some money. Cylinder head price mostly ranges from $200 to $500, while labor to install a new head costs between $50 to $ 100. Cylinder head resurfacing cost is much lower that.
- Product unavailability– the cylinder head could a discontinued design and not available on the market. If your vehicle uses the older flathead cylinder head, you may find repair the only way to continue using the part.
- When only mounted parts are damaged– it could be that only a few parts are damaged. If such is the case, cylinder head refurbishment would be a better option.
Most cylinder head repair tasks are relatively easy to carry out, as we shall see next. Some, like resurfacing or milling, may not be DIY-able since they require special tools. Despite that, you can easily get the services within your locality. Simple search phrases like “cylinder head repair near me” or “cylinder head repair shop near me” will give you many options to choose from.
As we have already seen, there are different cylinder head repair processes. You may choose to recondition the head, machine it, or seal voids. Costs also vary. Cylinder head reconditioning cost may be different from the amount for cracked cylinder head repair, for example. That is because refurbishing would involve several other parts.
Let us look at what the different repair tasks mean.
What is Cylinder Head Reconditioning?
It means giving the cylinder head a new face (and a new lease of life). Refurbished cylinder heads will go for a few more years, saving you the costs to buy a new piece. Problems that can be repaired this way include cracks and warps. Also worn components such as valve seals, valve guides, and other replaceable cylinder head parts.
Cylinder head refurbishment essentially involves disassembling, cleaning, and changing various components. Some parts may need to be resurfaced when reconditioning a cylinder head. The components include valve angles, valve seats, and generally warped spots.
Apart from optimizing the operation of the engine, cylinder head repair helps prevent wastage of fuel or damage by partially burnt air/fuel mixture. The following section show the steps to recondition a typical cylinder head.
Steps to Repair a Cracked Cylinder Head
Materials: Ratchet and socket set, valve spring compressor, and needle-nose pliers. You will also need cleaning materials such as solvent, wire brush, and gasket scraper. Have new oil and coolant with you, too.
Warning: To avoid shock, always remember to start by disconnecting the negative terminal of the battery.
Step 1 Draining the oil and coolant
Drain coolant by opening the radiator drain cap and oil by removing the plug on the oil pan.
Step 2 Removing the Cylinder Head Parts
Use a valve compressor, pliers, and ratchet and socket to disassemble the different components in this sequence: intake and exhaust manifolds, timing belt, and rocker arm or arms.
Remove also the valves, valve keepers, valve springs, seals, rocker, and other parts. Place each part in a labeled container. It will make assembly easy.
Step 3 Removing the Cylinder Head
Using the manufacturer’s recommended sequence, untighten and remove the head’s mounting bolts. Take the head off the engine block.
Step 4 Cleaning the Cylinder Head
The head will be covered by sludge or material buildup, such as carbon. Remove the deposits from both outside and inside. Clean the oil and coolant passageways, too, using the materials mentioned at the beginning.
Step 5 Examining the Cylinder Head
Once clean, the cylinder head is now ready to be inspected. Check it for cracks and pits. Fix openings with a sealant such as epoxy. There is no difference between aluminum cylinder head repair epoxy and the one used to on iron heads.
Using a micrometer, measure the camshaft to see if the dimensions are correct (within the specifications of the manufacturer). You can consult the car manual for the specs. Do not forget to inspect the camshaft for signs of wear.
Step 6 Inspecting Cylinder Head parts
Check the valve guides, rocker arms, studs, and other components for excessive wear. Replace damaged parts.
Step 7 Assembling the Cylinder Head
After ensuring the head is clean and every part in good condition, it is now time to assemble the parts. Use the same disassembly procedure to place the components back. The valves and other parts must be in their correct position, or the cylinder head will not work as required.
Step 8 Re-installing the Cylinder Head
After assembling the parts, it is now time to mount the cylinder head back on the engine block. Follow the steps to remove the head, ensuring to mount every component correctly. Do not forget to put new oil in the oil pan and new coolant.
A word of caution here: Some components may be confusing, and you may not be sure about their location during assembly. If in doubt, it is advisable to seek cylinder head repair service from your mechanic.
What is Cylinder Head Resurfacing?
Resurfacing means removing some parts of the cylinder head. It is usually done to restore the head’s flatness, remove deposits and weld joints, or improve surface finish. Sometimes, the heads are milled to reduce effective cylinder height and increase the compression ratio.
A cylinder head gasket is machined to improve its sealing properties. The gasket may not be producing an airtight seal and leaking coolant or oil. When carrying out cylinder head gasket repair, it is advisable to avoid excessive resurfacing.
Cylinder head resurfacing should be done the right way, efficiently, and using the right tools. A mistake can mean extra costs since the removed parts cannot be put back. To resurface a cylinder head, you need a resurfacing machine.
And if aiming to create a surface finish, the correct Roughness Average (Ra) specs for your particular head. The Ra value mostly depends on the cylinder head material. Wrong cylinder head machining can result in poor sealing at the gasket. The same applies to head gasket repair, as we have already seen.
Below are different resurfacing techniques.
Wet Grinding- grinding provides a smooth surface finish and the reason for its popularity among cylinder head refurbishment experts. A grinding wheel made of silicon carbide is usually used. However, it tends to overheat when resurfacing aluminum head, requiring the use of lubricant and coolant during the process.
Dry Milling- milling is faster than grinding and touted to be one of the best cylinder head repair methods available today. One pass removes a bigger piece of metal, unlike grinding, where multiple cuts are necessary. Dry milling is also less mess, and the introduction of polycrystalline diamond tools has improved the technique tremendously.
Belt Sanding- belt sanding is not as popular as milling or grinding. Its precision is largely limited and results generally depend on the person doing the resurfacing. However, it is/a simple technique that does not need fittings to mount the cylinder head. The abrasives used in a sanding belt range from silicone carbide, aluminum oxide to ceramics.
How to Repair a Blown Cylinder Head Gasket
A head gasket seals the head to the engine block, among other functions. Just like the cylinder head, the gasket can get damaged by high temperatures. A blown head gasket causes coolant and lubricant to leak. That, in turn, causes overheating and leads to more engine problems.
You can repair a blown head gasket easily and without requiring specialized tools. Start by checking the gasket for damage. Look for signs such as high engine temperature, low levels of coolant, contaminated oil, and white smoke at the exhaust.
You can also carry out a blown head gasket test. It is known as a leak-down test and essentially looks for the presence of combustion gases in the car’s cooling system. After confirming that you may have a bad gasket, make preparations for repair. Here is fix a blown head gasket and other problems.
Cylinder Head Gasket Repair Procedure
Things needed: Wrenches, a sealant such as epoxy, coolant, and oil.
Step 1
Disconnect the battery to avoid shock. Drain the radiator by opening the valve and placing a container underneath to hold the draining coolant.
Step 2 Getting at the Head Gasket
Use wrenches to loosen bolts and take out parts that prevent access to the gasket. The parts include air intake assembly, exhaust manifold, rocker arm, and the air conditioner pump. Remove also the water pump. Loosen the alternator and disconnect the radiator pipes or hoses.
Step 3 Taking the Cylinder Head Out
Remove the cylinder head bolts following the installation torquing sequence. You may need to consult the car’s manual for the sequence.
Step 4 Repairing the Head Gasket
Access the cylinder head gasket and check it for damage. Remove it from the engine block. There are three ways to fix the gasket.
- Resurface the gasket to achieve required flatness
- Clean and close leaks using sealant
- Tighten the bolts that hold the gasket to the engine block
Depending on the nature of damage, carry out repairs.
Step 5 Reassembling the Head Gasket
After the cylinder head gasket repair, it is now time to put it back. Use the same procedure as you did to take it out. Replace the coolant that you drained.
Cylinder head gasket repair is such a labor-intensive procedure. Most of the time, it is not a DIY thing. It requires a qualified professional who uses the right tools and processes. Very often, the repair involves fixing or replacing other parts such and can take from several hours to as long as a few days.
Conclusion
Cylinder heads and head gaskets are crucial parts. Their failure can bring about many problems such as leaks, overheating, and general engine performance issues. Some cylinder head or head gasket problems are repairable- easily and inexpensively. With the information in this article, you now understand how the components are fixed. When carrying out the repair ensure you have the right tools and repair knowledge. Otherwise, it is advisable to look for a mechanic to do the work.
