An internal combustion engine, found in most of the vehicles you see around, comes with a cylinder block comprising a couple of cylinders. The cylinder head sits on top of all the cylinders to seal and keep them safe. More importantly, the cylinder head houses passages for the mixture of fuel and air to facilitate combustion in the engine. It also has exhaust valves for removing the unwanted gases produced by combustion in the engine. All this work wears the cylinder head and you will have to recondition it for you to enjoy optimal engine performance. If you need to do this for the first time, here are the first four must-dos of cylinder head reconditioning:
Stripping the Cylinder Head
Internal combustion engines are complex machines assembled over long hours of precision engineering. Reconditioning the cylinder head begins with the careful stripping of the head to prevent any damage to the other parts of the engine.
Cleaning the Cylinder Head
After stripping the cylinder head, cleaning follows to remove the dirt and grime that has accumulated over time. A good service provider should clean the head using a waterjet and soap. Thereafter, the cylinder should be dried using dry, compressed air.
Hydraulic Testing of the Cylinder Head
Today, most manufacturers use two techniques when making cylinder heads. They either fit them with aluminium screw plugs or glue them together using Loctite. Both of these techniques must be tested hydraulically to identify any leaks in the cylinder head. Hydraulic testing involves the following steps:
- Loctite glued heads are taken off, refurbished, re-glued and clenched together using a special machine. This restores the cylinder head bond and ensures that no leaks occur.
- Cylinder heads sealed using aluminium screw plugs are re-drilled according to the manufacturer's guidelines. Air testing then follows at a pressure of about six kilogrammes per centimetre squared. If the leakage persists at the drilling points, then the hydraulic test is carried out again until the cylinder head stops leaking.
Restoring the Firing Place
The firing place refers to the point of ignition of the air/fuel mixture. For perfect fuel ignition, the fuel the firing place needs to be refaced. This begins with scrubbing the region with a scratch brush to remove rust, dirt and paint residue. The technician then uses a set of gauges to examine the flatness of the firing place. If the region has bumps and marks, then the technician must grind it to make sure that it as flat as required.