Automotive Systems

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Valve Guide Service

Valve Guide Service

Servicing of valve guides is an important, but often neglected, part of a good valve job. The guide must be clean and in good condition before a good valve seat can be made. Valve guide wear is a common problem; it allows the valve to move sideways in its guide during operation. This can cause oil consumption (oil leaks past the valve seal and through the guide), burned valves (poor seat to valve face seal), or valve breakage.

There are several satisfactory methods of checking for valve guide wear. One procedure for checking valve guide wear is to slide the valve into its guide. Full it open approximately 1/2 inch, then try and wiggle the valve sideways. If the valve moves sideways in any direction, the guide or stem is worn Another checking procedure involves the use of a small hole gauge to measure the inside of the guide and a micrometer to measure the valve stem; the difference in the readings is the clearance. Check the manufacturer's manual for the maximum allowable clearance. When the maximum clearance is exceeded the valve guide needs further servicing before you proceed with the rest of the job.

Servicing procedures depend on whether the guide is of the integral or replaceable type. If it is the integral type, it must be reamed to a larger size and a valve with an oversize stem installed. But if it is replaceable, it should be removed and a new guide installed

KNURLING of the valve guides has become more popular as a method of compensating for wear of the valve guides. Knurling is accomplished by attaching a special tool to an electric drill and inserting the tool in the worn guide. This method is not recommended if the guide has been worn excessively or knurled previously.

Valve guides should be removed and replaced with special drivers (fig. 3-59). When working on a valve in the cylinder head of an engine, you may use an arbor press to remove and replace the valve guides.

After the valve guides are serviced and the valve seats are ground, check the concentricity of the two with a valve seat dial indicator (fig. 3-60). Any irregularity in the seat will register on this dial.

Figure 3-59.—Puller used in removing valve seat inserts.

Figure 3-60.—Determining concentricity of the valve seat with a valve seat dial indicator.

Published by SweetHaven Publishing Services
Based upon a text provided by the U.S. Navy

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