There are two basic types of cylinder heads used on today’s automobiles: the Overhead
Valve (OHV) and the Overhead Camshaft (OHC). The latter can also be broken down into
two subgroups: the Single Overhead Camshaft (SOHC) and the Dual Overhead Camshaft
(DOHC).
Most cylinder heads are made of an aluminum alloy because it is light weight, highly
durable and transfers heat well. However, cast iron was the material of choice in the past,
and is still used on many vehicles today. Whether made from aluminum or cast iron, all
cylinder heads have valves and seats. Some use two valves per cylinder, while the more
hi-tech engines will utilize a multi-valve configuration using three, four and even five valves
per cylinder. All cylinder heads have a valve guide for each valve. The guide centers the
valve to the seat and allows it to move up and down within it. The clearance between the
valve and guide can be critical. Too much clearance and the engine may consume oil, lose
vacuum and/or damage the seat. Too little, and the valve can stick in the guide causing
the engine to run poorly if at all, and possibly causing severe damage. When the valve
contacts the seat, sealing the combustion chamber, it does so with precision-machined
surfaces. The last component all cylinder heads have are valve springs. The spring holds
the valve against its seat. It also returns the valve to the closed position after the valve has
opened. The spring is held in place around its corresponding valve by a retainer and valve
locks. Aluminum heads will also have a valve spring cup to prevent the spring from
wearing away the aluminum of the cylinder head.
Summary of Contents for TrailBlazer
Page 1: ......
Page 26: ...Fig 3 Typical body and undervehicle maintenance locations Refer to chart for descriptions ...
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Page 175: ...Spring free length check Valve spring squareness check ...
Page 192: ...Front of piston mark ...
Page 361: ...5 3L Engine Except Saab Underhood Fuse Block 2003 2005 Early Production ...
Page 469: ...Removing the outer band from the CV boot Removing the inner band from the CV boot ...
Page 470: ...Removing the CV boot from the joint housing Clean the CV joint housing prior to removing boot ...
Page 471: ...Removing the CV joint housing assembly Removing the CV joint ...
Page 472: ...Inspecting the CV joint housing Removing the CV joint outer snap ring ...
Page 473: ...Checking the CV joint snap ring for wear CV joint snap ring typical ...
Page 474: ...Removing the CV joint assembly Removing the CV joint inner snap ring ...
Page 475: ...Installing the CV joint assembly typical ...
Page 553: ...9 Torque the lug nuts to specification 10 Lower the vehicle ...
Page 556: ...Toe in Frame Misalignment Frame misalignment ...
Page 588: ...Bleeding caliper ...
Page 624: ...Manifold gauge set components Refrigerant recovery recycling station ...
Page 676: ...A C Specifications ...
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