Geely JL481Q, Manual, Page: 51 / 198

(3) Clean valve guide
Use valve guide brush and solvent to clean all valve guides (Fig. 77).
(4) Clean cylinder head
Use soft brush and solvent to clean cylinder head thoroughly (Fig. 78).
3. Check cylinder head
(1) Check planeness
Use precision ruler and feeler gauge to measure whether there is any warping on contact surfaces of cylinder head (Fig.
79). Specified max. allowable warping value of planeness: At cylinder block side: 0.030mm, manifold side: 0.08mm If
planeness exceeds the above-mentioned maximum value, replace the cylinder head.
(2) Check whether there is any crack Use dye penetrant to check (Fig. 80) whether there is crack in combustion chamber,
air inlet, air outlet and the surface of cylinder head. Replace cylinder head if any crack is found.
4. Clean valve
(1) Use scraper to eliminate carbon deposit attached on valve end.
(2) Use wire brush to eliminate fuel combustion residue on the valve thoroughly (Fig. 81).
Fig. 77 Clean valve guide Fig. 78 Clean cylinder head
Fig. 75 Don’t scrape surface when eliminating
residual material on contact surface of cylinder head
Fig. 76 Use wire brush to remove carbon
deposit in combustion chamber
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