Rebuilt Cylinder Heads-The Process
In many cases, most cylinder heads are usually salvageable and relatively inexpensive to repair. Rebuilt cylinder heads normally cost less than half of the price of a new cylinder head.
A rebuilt cylinder head is a head that has been remanufactured with parts that are still working. In most cases, the heads have been repaired and welded depending on what the problem was. The cylinder head is then pressure tested to make sure there are no leaks in the casting. New valve seats may be installed if they are needed. Valves are replaced as necessary or ground to the factory specifications. Valve springs are then tested and the heads are painted, resurfaced and then totally reassembled.
Sometimes repairs can be made without having to remove the cylinder heads on some vehicles. Repairs such as replacement of the camshaft seals and camshaft, valve stem seals, hydraulic lash compensators, lifters, valve springs, rocker arms and cam followers.
Rebuilt cylinder heads follow a specific remanufacturing process. Inspection of the head before tearing it down is essential to see if the problem can be seen from the outside. Disassembling begins with the removal of the springs, valves, cam and other parts. The surface of the cylinder head and the line bore are then checked to make sure of alignment of the camshaft. Thermal cleaning comes next which is where the bare cylinders are put in an oven for several hours. The grease is the removed by using either shot blast for cast iron heads or glass beads for cylinder heads made of aluminum. A crack check is then accomplished and all damaged threads are repaired.
The cracks then repaired. The aluminum head is welded or cracks can be stitched in cast iron. The new valve seats are then installed as necessary. A cylinder head can be straightened if it is extremely warped. The head is mounted on a metal plate, torque and shimmed. It is then placed in a five hundred degree oven for four hours. The valves are machined to factory specs. The seats guides are repaired or replaced. The cylinder head is resurfaced. Valves are checked for the right tension and height. The new valve seals are then installed and reassembly ot the rebuilt cylinder head begins.
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