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
See Figures 1 and 2
- 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 using an accurately positioned cooking thermometer to determine temperature; 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 will caus them to contract making them easier to install.
- Using a hammer and the Valve Guide Driver tool No. 07942-SA50000, 07942-8230000 or equivalent (for exhaust side) or 07942-6570100, 07942-6110000 or equivalent (for intake side), drive the valve guide(s) toward thecamshaft side of the cylinder head.
- Using a hammer and the Valve Guide Driver tool No. 07942-SA50000, 07942-8230000 or equivalent (for exhaust side) or 07942-6570100, 07942-6110000 or equivalent (for intake side), remove the new guide from the freezer and drive it into the cylinder head from the camshaft side until the guide projects above the cylinder head surface. Valve guide installed height for 1984-87 engines is 0.8 in (20.0mm) (intake), and 0.76 in (19.0mm) (exhaust); for 1988-91 engines it is 0.648 in. (16.2mm); for 1992-95 D16Z6, D15Z1 engines it is 0.714-0.734 in (17.85-18.35mm) (intake), and 0.746-0.766 in. (18.65-19.15mm) (exhaust); for 1992-95 D15B7, D15B8 engines it is 0.638-0.658 in. (15.95-16.45) (intake and exhaust).
If installing a whole set of guides (8 or 16 depending on engine), it may be necessary to re-heat the cylinder head more than once.
- 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 elsewhere in this section.
When replacing the valve springs, place the closely wound end toward the cylinder head.
- To assemble the cylinder head, first lubricate the valves with clean engine oil and slide the valves up and down in the valve guides to make sure they move smoothly.
- Then install the valve guide seals and lubricate the parts with clean engine oil. Use a valve spring compressor to compress the valve springs and carefully install the valve keepers, retainers and springs. (The exhaust valve seal uses a black spring, while the intake valve seal uses a white spring.)
- After removing the valve spring compressor, tap the valve stems 2-3 times to make sure the valve keepers and valves are fully seated. Only tap each valve stem along its axis so you do not bend it.
- Refer to "Rocker Arms/Shafts, Installation" and "Camshaft, Installation" in this section for procedures to assemble the rest of the cylinder head.
- To complete the installation, use new gaskets and install the cylinder head on the vehicle.
- Refill the cooling system. Start the engine and check for normal operation and leaks.
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.