Service manual

181 CID (3.0L) 4 CYLINDER GM ENGINE
SERVICE MANUAL NUMBER 26
90-861329--1 MARCH 1999 Page 3A-27
5. Thoroughly clean valve guides with valve guide cleaner (J-8101).
74286
a
a-Valve Guide Cleaner (J-8101)
Inspection
1. Inspect cylinder head for cracks in exhaust ports, water jackets and combustion cham-
bers (especially around spark plug holes and valve seats). Replace heads if any cracks
are found.
2. Inspect cylinder head gasket surface for burrs, nicks, erosion or other damage. Check
flatness of cylinder head gasket surface, using a machinist’s straight edge and feeler
gauges as shown. Take measurements diagonally across head (both ways) and straight
down center head. Refer to “Specifications.”
72885
b
a
a-Straight Edge
b-Feeler Gauge
IMPORTANT: Cylinder head-to-block gasket surface should be resurfaced if warped
more than specified. When head resurfacing is required, cylinder head-to-intake
manifold gasket surface on head must be milled to provide proper alignment
between intake manifold and head.
3. Inspect valves for burned heads, cracked faces or damaged stems.
IMPORTANT: Excessive valve stem to bore clearance will cause excessive oil
consumption and possible valve breakage. Insufficient clearance will result in noisy
and sticky valves.
4. Measure valve stem clearance as follows:
a. Attach a dial indicator to cylinder head, positioning it against the valve stem and
close to the valve guide.
b. Holding valve head off seat about 1/16 in. (2 mm), move valve stem back and forth
in direction shown. Compare stem clearance with specifications.
Index