Inspection

CYLINDER HEAD


Inspection


INSPECTION AFTER REMOVAL

Cylinder Head Bolts Outer Diameter
- Cylinder head bolts are tightened by plastic zone tightening method. Whenever the size difference between (C) and (B) exceeds the limit, replace them with new one.





Limit [(C) - (B)] : 0.18 mm (0.0071 in)

- If reduction of outer diameter appears in a position other than (B) use it as (B) point.

Cylinder Head Distortion

NOTE:
When performing this inspection, cylinder block distortion should be also checking. Refer to Inspection.
1. Using a scraper, wipe out oil, scale, gasket, sealant and carbon deposits from surface of cylinder head.

CAUTION:
Never allow gasket fragments to enter engine oil or engine coolant passages.





2. At each of several locations on bottom surface of cylinder head, measure the distortion in six directions (A, B, C, D, E, and F).

Limit : Refer to "Cylinder Head". Cylinder Head

- If it exceeds the limit, replace cylinder head.

INSPECTION AFTER DISASSEMBLY

Valve Dimensions
- Check the dimensions of each valve. For the dimensions, refer to Cylinder Head.
- If dimensions are out of the standard, replace valve and check valve seat contact. Refer to "VALVE SEAT
CONTACT".

Valve Guide Clearance

Valve Stem Diameter
- Measure the diameter of valve stem with micrometer (A).






Standard (Intake and exhaust) : Refer to "Cylinder Head". Cylinder Head

Valve Guide Inner Diameter
- Measure the inner diameter of valve guide with bore gauge.

Standard (Intake and exhaust) : Refer to "Cylinder Head". Cylinder Head

Valve Guide Clearance
- (Valve guide clearance) = (Valve guide inner diameter) � (Valve stem diameter)

Valve guide clearance : Refer to "Cylinder Head". Cylinder Head
Standard and limit (Intake and exhaust)

- If the calculated value exceeds the limit, replace valve and/or valve guide. When valve guide must be replaced, refer to Disassembly and Assembly.

Valve Seat Contact
- After confirming that the dimensions of valve guides and valves are within the specifications, perform this procedure.
- Apply Prussian blue (or white lead) onto contacting surface of valve seat to check the condition of the valve contact on the surface.
- Check if the contact area band is continuous all around the circumference.





- If not, grind to adjust valve fitting and check again. If the contacting surface still has "NG" (B) conditions even after the recheck, replace valve seat. Refer to Disassembly and Assembly.

Valve Spring Squareness
- Set a try square (A) along the side of valve spring and rotate spring. Measure the maximum clearance between the top of spring and try square.






Limit : Refer to "Cylinder Head". Cylinder Head

- If it exceeds the limit, replace valve spring.

Valve Spring Dimensions and Valve Spring Pressure Load
- Check the valve spring pressure at specified spring height.






Standard (Intake and exhaust) : Refer to "Cylinder Head". Cylinder Head
Free height
Installation height
Installation load
Height during valve open
Load with valve open

- If the installation load or load with valve open is out of the standard, replace valve spring.

INSPECTION AFTER INSTALLATION

Inspection for Leakage

The following are procedures for checking fluids leakage, lubricates leakage and exhaust gases leakage.
- Before starting engine, check oil/fluid levels including engine coolant and engine oil. If less than required quantity, fill to the specified level. Refer to Maintenance.
- Use procedure below to check for fuel leakage.
- Turn ignition switch "ON" (with engine stopped). With fuel pressure applied to fuel piping, check for fuel leakage at connection points.
- Start engine. With engine speed increased, check again for fuel leakage at connection points.
- Run engine to check for unusual noise and vibration.
- Warm up engine thoroughly to check there is no leakage of fuel, exhaust gases, or any oil/fluids including engine oil and engine coolant.
- Bleed air from lines and hoses of applicable lines, such as in cooling system.
- After cooling down engine, again check oil/fluid levels including engine oil and engine coolant. Refill to the specified level, if necessary.