Nissan Micra Cylinder Head Disassembly & Inspection - Warpage & Valve Guide Specs

This is page EM-11 of a Nissan engine service manual covering cylinder head disassembly (continued) and inspection procedures. The disassembly section lists steps 4–7: remove the rocker shaft with rocker arms, remove the camshaft, remove valve component parts using special tool KV101092S0 (a valve spring compressor), and remove valve oil seals using special tool KV10107900. Illustrations (SEM031B, SEM991, SEM644) accompany each step. The inspection section covers two checks. First, cylinder head distortion: the gasket surface is measured with a straightedge and thickness gauge at multiple points in an X-pattern; warpage must be less than 0.1 mm (0.004 in). If beyond the limit, the head must be resurfaced, but the combined amount of head resurfacing ("A") plus block resurfacing ("B") must not exceed 0.2 mm (0.008 in). Second, valve guide clearance: it should be measured parallel to the rocker arm, where most wear occurs. The stem-to-guide clearance maximum limit is 0.10 mm (0.0039 in), with maximum allowable deflection (dial indicator reading) of 0.2 mm (0.008 in), measured at 28 mm (1.10 in) valve lift height. Illustrations SEM006A and SEM005A show the measurement setups.