Getting Ahead of Cylinder Heads

As part of our Tip of the Week series, we’ve previously provided productivity tips for many important engine components. But, one component that we haven’t yet covered is the cylinder head – a critical component that along with the engine block makes up the cylinder.

Sit back and take in this week’s tip to learn the basics about keeping your cylinder head in peak condition.

Cylinder head basics

In an engine, the cylinder block sits of top of the block, separated by the head gasket, to create the cylinder. The block contains the pistons, and once the piston head is in place, the combustion chamber is created. This union provides an area where gases and fuel are introduced, compressed, and ignited. After compression, the exhaust gasses allowed to escape.

Cylinder head

The head is cast and typically made of lightweight aluminum or iron. It allows for the mounting of the valves, springs, push rods, rocker arms, guides, spark plugs (if equipped) and fuel injectors. Head design is typically side valve, although older engines may be of flat head design. In overhead cam engine designs, the cylinder head also contains the cam shaft. On the underside, or combustion side, the head contains the valves seats. The cylinder head contains passages or internal ducts, allowing engine coolant to pass through it, helping to removing heat from combustion.

The number of heads contained in an engine depends on the design and size of the engine. Mobile engines that are in-line, typically four- or six-cylinder engines, usually have one head. In “V” or horizontal engines, there are heads for each bank of pistons. As an example, a V-8 engine would have two heads, one for each four-cylinder bank. In large stationary engines in excess of 600 HP, independent heads may be installed on each cylinder. This is largely due to the weight of the head and for ease of maintenance.

Cylinder head lubrication and cooling

Lubrication of a cylinder head is done from the engine crankcase. The installed oil pump pushes oil up to the cylinder deck. Once the oil reaches the cylinder deck, it lubricates the push rods, overhead cam (if contained), rocker arm assembly, springs by default, and the valve stems. It is guided by bath or splash.

Oils used in cylinder heads are typically multi- or straight-weighted engine oils. They are designed with premium base stocks and additives that deliver exceptional performance and must have:

  • Outstanding oxidation stability
  • Anti-wear capability
  • Excellent soot and viscosity control

These oils may also meet or exceed the requirements of typical heavy-duty engine oil performance categories API CK-4, CJ-4, CI-4 PLUS, CI-4 or CH-4, and in many cases meet API “S” specifications for gasoline engines and key OEM requirements.

As stated earlier, the cylinder head contains passages allowing engine coolant, typically ethylene or propylene glycol, to pass through it. This helps to remove waste heat from combustion. It’s essential to controlling heat to keep the cylinder head form over-expanding and cracking. Engine coolant is provided by the water pump and contained in a circulation system that made up of the radiator, hoses, expansion tanks, block, cylinder head, and expansion tank.

I hope this tip was helpful, and if you have any more questions, don’t hesitate to leave a comment in the section below!