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Understanding Cylinder Heads

Posted by Scott Goldfarb on

Your diesel engine is comprised of many complex parts, but one of the most complex parts of any diesel engine is the cylinder head. There are more moving parts in the cylinder head than there are in any other part of the engine.

Since cylinder heads are in a fixed position and sealed with the head gasket, they are rarely in need of being replaced because they experience much less wear than other parts of the engine. But, because of the complexity of the cylinder head and the intricacy of all of its parts, replacing or repairing a cylinder head is also complicated, and it can be expensive, too. What does a cylinder head do, and what problems could a damaged cylinder head cause? Keep reading to find out all you need to know about cylinder heads.

What does a Cylinder Head do?

A cylinder head allows the air and fuel to flow in and the exhaust gases to flow out of the cylinders. Its main purpose is to close off the combustion chamber of the engine (to the lower part of the engine called the engine block) from the top (the cylinder head).

The cylinder head also lubricates the cylinder constantly. This constant lubrication facilitates the smooth operation of the engine, making the cylinder head a crucial part of the engine.

The cylinder head is subjected to extreme temperatures, but it avoids overheating and damage because of the coolant that runs through the engine. Cylinder heads are sometimes made of aluminum alloys and light metals that can dissipate heat. However, some cylinder heads are made of cast iron, as it is more durable and less expensive, but it is less efficient at helping to cool the engine.

What is in a Cylinder Head?

Cylinder heads have many parts.

  • Intake and exhaust ducts and valves: The intake and exhaust ducts and diesel fuel valves allow the air and air-fuel gas mixtures to travel in and out of the engine.
  • Springs: Engines use valve springs to close the exhaust and intake valves.
  • Diesel camshaft: The valves are opened and closed by camshafts (which are driven by the timing chain).
  • Injectors: The injectors inject fuel into the combustion chambers of the diesel engine.
  • Combustion chamber: The combustion chamber is the area within the head cylinder where the mix of fuel and air is ignited. After it is combusted, it is pushed out of the combustion chamber as a form of energy.

Potential Cylinder Head Problems

Because cylinder heads experience much less wear than other parts of the engine and therefore do not need to be serviced as regularly as other parts of the engine, how can you know if your diesel engine is having problems with its cylinder head? This list shows potential issues that could arise from a damaged cylinder head.

1. Overheating. Caused by cracked cylinder head leaking coolant and overheating the engine. A crack in the cylinder head will also cause the oil to leak into the combustion chambers. This can cause irreversible damage that would result in the entire engine needing to be replaced.

2. Smoke. If you see excessive smoke coming from the exhaust, it may indicate a cracked cylinder head. If smoke is present, the damage to the cylinder head is more likely to be severe. If you see smoke, it is in your best interest to have the engine examined by an experienced professional as soon as possible to prevent further damage.

3. Oil leaks. Oil leaking from your vehicle may be coming from a cracked cylinder head. Whenever you have an oil leak, check the area around the cylinder head for evidence of excess oil.

4. Drop in Coolant Level. A cracked cylinder head could also contribute to coolant leaks, which would drop the level of coolant in the engine. Not only would the cracked cylinder head need to be replaced, but if it is not caught soon enough, the lack of coolant could cause a lot of other damage to the engine from overheating.

5. Poor Engine Performance. If a cylinder head is cracked or broken, fuel is not able to be burned as efficiently. When fuel is not burned efficiently, the result is poor engine performance. The poor engine performance will manifest itself in the engine needing to be restarted frequently.

If your car is experiencing problems you suspect could be related to the cylinder head of your engine, have it checked out as soon as possible. What may start as a minor problem could escalate if not addressed quickly.

If you are in need of parts for your cylinder head (or any other part of your diesel engine), you can find them on our website.


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