Cylinder Head Resurfacing
Only engine professionals invest in quality machine shop equipment
Roughness Average (Ra) is the average micro-inch measurement of peak-to-valley roughness height of a “flat” surface. The lower the Ra number, the smoother the surface. When the cylinder head surface is straight and true the lifespan of the gasket is extended, if left ignored a newly installed gasket can cause leaks especially if the engine was previously overheated, when an overheat occurs the cylinder head can warp and cause uneven tension on the gasket.
When the surface is too rough it is necessary to take off a very small amount of material to make the surface smooth. We also take a measurement across the entire cylinder head to check for warpage, if the head is warped as little as the width of a human hair about 0.004 inches the head must be surfaced to bring it straight again.
Wash & Assembly
Now that the cylinder head surface is within specification it is washed in our ultrasonic cleaner to remove all metal cuttings. After it is dried and is assembled and awaits installation onto the cylinder block.
Cylinder Block Washing
Frankly Its a dirty job!
Depending on the type of engine failure different types of contamination can occur, in this case the customer snapped a connecting rod. The connecting rod fragments destroyed the inside of the block allowing the coolant from the cooling passageway to engine the oil cavity. The only solution is to dispose of the contaminated oil properly to send to a recycling facility for reclamation. Despite the engine block being broken there are many components we can salvage bringing down the cost of the engine build.
In modern diesel engines SCR catalysts can fail causing increased backpressure, this can cause the engine oil to exceed acceptable temperatures causing the oil to "cook" This presents itself as a goop that sticks to everything and is heavily contaminated with soot particles. The engine must be power washed first before solvents are applied to break down the oils before caustic acid washing is done.
Lake water Contamination
In marine applications when the engine is not properly winterized the remaining water in the cooling passageways freeze. The expanding ice is capable of splitting cast iron like a toothpick! When the operator runs the engine in this situation the lake water mixes with the engine oil. The engine oil pump then churns the mixture into a fine pancake like batter that is very difficult to remove from components that would come in contact with engine oil.
When an engine is dismantled one of the first steps is to inspect the bore for excessive wear, in this case uneven cylinder temperature is the cause of failure, The excessive heat deformed the pistons and in conjunction with high running hours allowed this type of damage to occur
The cylinder block is completely washed to allow the remaining cylinder to be measured for sizing in most cases the allowable wear deviation is between 0.001 - 0.003 thousands of an inch! If the measurement exceeds manufacturer specification the cylinder is either bored to the next available piston size or a cylinder liner/sleeve will be installed.
Now that the cylinder is back to manufacturer specification the new piston can be installed. If the boring step is not performed correctly or skipped the engine will burn a large amount of oil or the piston with crack and cause catastrophic damage to the cylinder block