FREE REPAIR MANUALS & LABOR GUIDES 1982-2013 Vehicles
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Home >> Chevy Truck >> 1999 >> Tracker 4WD L4-2.0L VIN C >> Repair and Diagnosis >> Engine, Cooling and Exhaust >> Engine >> Service and Repair >> Overhaul >> Repair Instructions >> 36. Valve Guide Reaming, and Valve and Seat Grinding >> Valve Seat Repair

Valve Seat Repair





Important: Proper reconditioning of the valve seats is very important. Because the valve guide serves to support and center the valve grinder, it is essential that the valve guide is cleaned properly. If the valve guide requires reaming, this must be done first.

1. Use the following as a general guideline when reconditioning the cylinder head.
^ Ream the valve guide bores first and then recondition the valve seats.
^ Inspect the valve seats for excessive wear and burned spots. Valve seats may be reconditioned by grinding. If grinding results in the new seat being too wide it may be narrowed by using a 20 degree or 70 degree stone. The 20 degree stone will lower the seat and the 70 degree stone will raise the seat.
^ The valves must seat perfectly for the engine to deliver optimum power and performance.
^ Cooling the valve heads is another important factor. Good contact between each valve and its seat in the cylinder head is necessary to insure that the heat in the valve head is properly carried away.
^ Regardless of what type of equipment is used, it is essential that the valve guide bores are free from carbon or dirt to ensure the proper centering of the pilot in the guide.
^ The valve seats should be concentric to within 0.05 mm (0.031 inch) total indicator reading.
^ Replace any valve that is not in serviceable condition.
^ Several different types of equipment are available for reconditioning valves and valve seats. Use the manufacturers recommendations to obtain proper results.





2. Grind the exhaust valve seat first with a 15 degree stone (1) and then with a 45 degree stone (2).
Exhaust Valve Seat Width: 1.1-1.3 mm (0.043-0.0512 inch)





3. Grind the intake valve seat first with a 15 degree stone (1), then with a 60 degree stone (3) and then with a 45 degree stone (2).
Intake Valve Seat Width: 1.1-1.3 mm (0.043-0.0512 inch)
4. Lap the valves and seats with a coarse compound and then with a fine compound.
5. Clean all traces of the grinding compound from the valve components before final assembly.
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