Everything you need to know about a Cylinder Head.


Everything you need to know about a Cylinder Head.

What is a Cylinder Head?


In an internal combustion engine, the cylinder head (often informally abbreviated to just head) sits above the cylinders on top of the cylinder block. It closes in the top of the cylinder, forming the combustion chamber. This joint is sealed by a head gasket.


What does a Cylinder Head do?


A cylinder head is usually located on the top of the engine block. It serves as a housing for components such as the intake and exhaust valves, springs and lifters and the combustion chamber. This page covers the main function and various designs of cylinder heads, and their causes and symptoms of failure.


General Information about a Cylinder Head.

The cylinder head is located at the top of the engine block. Made from aluminum or iron, it seals the piston chambers, ensuring adequate pressure within them. The first engines using this technology, comparable with the modern engines used to power automobiles today, were patented in the early 1860s. Since this innovation overcame the problem of containing the controlled explosion of fuel within the engine block, the basic design of engines with cylinder block, pistons and cylinder head has barely changed as of 2010.

Head Gasket

The head gasket, usually made from a thin piece of steel, seals the joint between the engine block and the cylinder head. Without the gasket the seal between them, the two components would fail, causing a loss of pressure that would in turn reduce the power output of the engine. Water could also enter the cylinder chamber and mix with engine oil, causing overheating and damage to the internal components.


Your car runs on the ignition of a mixture of fuel and air. Channels within the cylinder head allow gas left over from this ignition to flow away from the engine and into the exhaust system via the exhaust manifold. This channeling removes heat from the engine and prevents the internal pressure from rising too high and causing an explosion.


On overhead valve engines, the inlet valve assembly sits at the top of the piston chamber, within the cylinder head. The valves control the flow of fuel and air into the piston chamber before the spark plugs ignite them. In the place of these valves, fuel-injected engines have injection nozzles that force the fuel-air mixture into the cylinder chamber.

Spark Plug Mounts

Each cylinder requires an ignition source to ignite the fuel-air mixture. Spark plugs are fitted through threaded holes in the cylinder head with their electrodes inside the piston chamber. The threaded holes ensure a gas-tight seal, maintaining the pressure within the cylinder chamber.


Engines with an overhead camshaft have the camshaft assembly housed withing the cylinder head.The engine’s crankshaft, located at the bottom of the engine block, drives the camshaft by means of a belt or chain. As it rotates, it opens the inlet valve of the next cylinder to fire.

Main symptoms of cylinder Head giving problems?


A cylinder head is a very important part of any car engine. Prices for repairing or replacing a cracked or broken cylinder head will vary depending on your vehicle’s engine and where you choose to get it repaired. In this article we discuss cylinder head troubleshooting to make you aware of some of the most common symptoms of cylinder head problems and help you identify them straight away, hopefully saving you time and money long-term. 

What is the Main job of the Cylinder Head?


A vehicle’s internal combustion engine contains many cylinders, with the top of them know as the cylinder head, housing various valves, springs, lifters and also the main combustion chamber. Controlling flow within the cylinders, the cylinder head allows air and fuel in and exhaust gases out. In addition, the cylinder head is a key component in keeping the engine components cool, by transporting coolant into the engine block. The cylinder head, alongside the head gasket, seals the cylinders in the vehicle and all the components that work with them. 

Most common symptoms of cylinder head problems:


Overheating of the engine is the most common symptom of cylinder head issues occurring in a vehicle. As the cylinder is put under pressure by the heat, it causes the components inside the internal combustion engine to overheat, as they can’t pass coolant through and, therefore, they distort in shape. Make sure your radiator is full and in good condition to prevent this from happening and to avoid damage to the cylinder head.


Poor Engine Performance


This is a very clear indicator that there is a cylinder problem which will be instantly noticeable as the engine won’t be running the same and you’ll find you may have to restart the car more frequently. This is because the engine isn’t able to burn fuel efficiently, due to the cylinder head breaking or cracking.


Oil Leaks


If you find you have oil leaking from the vehicle, this may be a result of a cracked cylinder head. As the cylinder head contains oil, if it’s cracked it may cause oil to leak out. Even if you can’t see a leak yourself and the oil light appears on the dashboard, check the engine to see if there’s any evidence of oil around the cylinder head.  


Drop in Coolant Levels


If there is a drop in the level of engine coolant it may cause a leak, which can be easily identified and be seen on the cylinder head. A leak could be caused due to a crack in the cylinder head and this could cause more long-term issues as the engine starts to heat up from the lack of coolant.




Smoke coming from the exhaust is the clearest indicator that you could have a cracked cylinder head. The crack and damage is most likely to be a lot more severe in this instance. If this has occurred, you should try and get this problem fixed as quickly as possible by a professional, to ensure no further damage is caused to the engine.


If you need a new cylinder head due to damage, then it’s important to remember that all diesel engines are different and, as such, no ‘one size fits all’ solution exists for any one diesel engine problem, whether common or uncommon.


It must also be noted that it’s imperative to determine the cause of the problem and address this before simply replacing damaged parts and re-assembling the engine. 


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