If replacement valve guides are not available or you determine the replacement procedure is too involved, the guides can be reconditioned using a procedure known as knurling (machining the inner surface).
REMOVAL & INSTALLATION
- Refer to the Valve, Removal & Installation procedures in this section and remove the valves.
- Place the cylinder head in an oven and heat it to 300°F; this procedure will loosen the valve guides enough to drive them out.
- Place the new valve guides in the freezer section of a refrigerator for about an hour; this contraction procedure will make them easier to install.
- Using a hammer and the Valve Guide Driver tool No. 07942-SA50000, 07942-8230000 or equivalent (exhaust) or 07942-6570100, 07942-6110000 or equivalent (intake), drive the valve guide(s) toward the camshaft side of the cylinder head.
- Using a hammer and the Valve Guide Driver tool No. 07942-SA50000, 07942-8230000 or equivalent (exhaust) or 07942-6570100, 07942-6110000 or equivalent (intake), remove the new guide from the freezer and drive it into the cylinder head from the camshaft side until the guide projects 15.5mm above the cylinder head surface.
- Using the Valve Guide Reamer tool No. 07984-SA50000, 07984-689010A or equivalent (exhaust) or 07984-6110000, 07984-657010A or equivalent, coat the reamer with cutting oil and ream the valve guides to the proper valve stem fit. Use the reamer with an in-out motion while rotating it. For the finished dimension of the valve guide, check the Valve Specifications chart.
Do not forget to install the valve guide seals.
- To assemble, reverse the disassembly procedures.
- To complete the installation, use new gaskets and reverse the removal procedures. Refill the cooling system. Start the engine and check for leaks.
See Figure 1
Knurling is a process in which the metal on the valve guide bore is displaced and raised, thereby reducing the clearance. It also provides excellent oil control. The option of knurling rather than reaming valve guides should be discussed with a reputable machinist or engine specialist.