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 "A" and "B" exceeds the limit, replace them with new one.






- If reduction of outer diameter appears in a position other than "d2", use it as "d2" point.

Cylinder Head Distortion

NOTE:
When performing this inspection, cylinder block distortion should be also checking. Service and Repair.
1. Using a scraper, wipe off 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.

Limit : Refer to Specifications.

- If it exceeds the limit, replace cylinder head.

VALVE DIMENSIONS
- Check dimensions of each valve. For dimensions, Specifications.
- If dimensions are out of the standard, replace valve.

VALVE GUIDE CLEARANCE

Valve Stem Diameter





Measure the diameter of valve stem with a micrometer (A).

Standard : Refer to Specifications.

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

Standard : Refer to Specifications.

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

Standard and Limit : Refer to Specifications.

- If it exceeds the limit, replace valve guide and/or valve. When valve guide must be replaced. Disassembly And Assembly.

VALVE SEAT CONTACT
- After confirming that the dimensions of valve guides and valves are within 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 conditions (B) even after the recheck, replace valve seat. Disassembly And Assembly.

A : OK

VALVE SPRING SQUARENESS





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

B : Contact

CAUTION:
Never remove valve spring seat from valve spring.

Limit : Refer to Specifications.

- If it exceeds the limit, replace valve spring (with valve spring seat).

VALVE SPRING DIMENSIONS AND VALVE SPRING PRESSURE LOAD





- Check valve spring pressure with valve spring seat installed at the specified spring height.

CAUTION:
Never remove valve spring seat from valve spring.

Standard : Refer to Specifications.

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

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.
- 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.