SEAL-O-RING 5F3999 - Caterpillar

Remove the cylinder head from the engine.
Remove the water temperature regulator housing.
Inspect the cylinder head for signs of gas or coolant leakage.
Remove the valve springs and valves.
Clean the bottom face of the cylinder head thoroughly. Clean the coolant passages and the lubricating oil passages. Make sure that the contact surfaces of the cylinder head and the cylinder block are clean, smooth and flat.
Inspect the bottom face of the cylinder head for pitting, corrosion, and cracks. Inspect the area around the valve seat inserts and the holes for the fuel injection nozzles carefully.
Test the cylinder head for leaks at a pressure of 200 kPa (29 psi).
Illustration 1 g01332569
Flatness of the cylinder head (typical example)
(A) Side to side
(B) End to end
(C) Diagonal
Measure the cylinder head for flatness. Use a straight edge and a feeler gauge to check the cylinder head for flatness.
Measure the cylinder head from one side to the opposite side (A).
Measure the cylinder head from one end to the opposite end (B).
Measure the cylinder head from one corner to the opposite corner (C).Refer to Specifications, "Cylinder Head" for the requirements of flatness.Resurfacing the Cylinder Head
The bottom face of cylinder head can be resurfaced if any of the following conditions exist:
The bottom face of the cylinder head is not flat within the specifications.
The bottom face of the cylinder head is damaged by pitting, corrosion, or wear.Note: The thickness of the cylinder head must not be less than 94.80 mm (3.7323 inch) after the cylinder head has been machined.Note: The dimension of the valve seats to the flame face must be corrected after resurfacing the cylinder head. Refer to Specifications, "Cylinder Head" for the correct dimensions for the valve seats.