Cylinder head quality inspection focuses on the following dimensions:

I. Core Inspection Items
Flatness Inspection
Standard Value: Overall flatness error no more than 0.05mm, local flatness error (50mm x 50mm area) no more than 0.03mm.
Method: Use a knife-edge ruler and feeler gauge to measure lateral, vertical, and diagonal warpage.
Risk: Exceeding tolerances can lead to seal failure, oil leaks, oil burning, or coolant seepage into the combustion chamber.

Appearance and Dimensional Inspection
Inspect for surface cracks, pores, pinholes, and deformation and wear.
Measure key dimensions such as cylinder bore and valve seat diameter to ensure they meet design tolerances.

Valve System Inspection
Valve seat seal: Ensure there are no leaks to prevent unstable idling or power loss.
Valve seal condition: Aging can lead to oil burning. Observe for "stone-like" carbon deposits.

Water and Oil Passage Inspection
Check that coolant passages are unobstructed to avoid engine overheating due to blockage. Oil passage leaks can cause the oil to emulsify (disappearing milky white), requiring pressure testing for verification.
II. Auxiliary Inspection Items
Material Analysis: Verify that the cylinder head (cast iron/aluminum alloy) meets high-temperature resistance and deformation resistance requirements.
Bolt Tightness: Looseness may cause cylinder head deformation or gasket failure.
III. Fault Correlation Detection
Symptoms of Seal Failure: Abnormal idling noise (squeaking), blue smoke (oil burning) or white smoke (coolant leakage) from the exhaust pipe.
High-Temperature Risk Points: An overly thin cylinder block design can easily cause high-temperature deformation, requiring special inspection of the cylinder head heat dissipation structure.
Note: High-performance engines have stricter flatness requirements (as low as 0.5 microns), so the inspection should be tailored to the vehicle model.