Suzuki Engine 2002 GRAND VITARA SQ420 Service Manual page 546

• Check cylinder head for cracks on intake and exhaust ports,
combustion chambers, and head surface.
Using straightedge and thickness gauge, check flatness of
gasketed surface at a total of 6 locations. If distortion limit,
given below, is exceeded, correct gasketed surface with a
surface plate and abrasive paper of about #400 (Waterproof
silicon carbide abrasive paper) : Place abrasive paper on
and over surface plate, and rub gasketed surface against
paper to grind off high spots. Should this fail to reduce thick-
ness gauge readings to within limit, replace cylinder head.
Leakage of combustion gases from this gasketed joint is
often due to warped gasketed surface : such leakage results
in reduced power output.
Limit of cylinder head gasketed surface distortion
0.05 mm (0.002 in.)
• Distortion of manifold seating faces :
Check seating faces of cylinder head for manifolds, using a
straightedge and thickness gauge, in order to determine
whether these faces should be corrected or cylinder head
replaced.
Limit of manifold seating face distortion
0.10 mm (0.004 in.)
ENGINE MECHANICAL (J20 ENGINE) 6A4-57