Inspection After Disassembly

Cylinder Head Bolts Outer Diameter 

• Cylinder head bolts are tightened by plastic zone tightening method. Whenever the size difference between (B) and (A) exceeds the limit, replace them with new one.

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  Limit [(B) - (A) ]

  : 0.18 mm (0.0071 in)

  c	: 55 mm (2.17 in)
  d	: 12 mm (0.47 in)

• If reduction of outer diameter appears in a position other than (A), use it as (A) point.

Cylinder Head Distortion 

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, F).

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   Limit

   : Refer to Cylinder Head .

   • If it exceeds the limit, replace VVEL ladder assembly & cylinder head assembly.
     NOTE: Cylinder head assembly cannot be replaced as a single part, because it is machined together with VVEL ladder assembly.

Valve Dimensions 

• Check the dimensions of each valve. For the dimensions, refer to Cylinder Head .
• If dimensions are out of the standard.
  • Replace valve (EXH) and check valve seat contact. Refer to "VALVE SEAT CONTACT". (Exhaust side)
  • Replace VVEL ladder assembly & cylinder head assembly. Refer to Exploded View . (Intake side)
    NOTE: Since the valve (INT) cannot be replaced by the piece, VVEL ladder assembly & cylinder head assembly replacement are required.

Valve Guide Clearance 

Valve Stem Diameter

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

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  Standard

  : Refer to Cylinder Head .

Valve Guide Inner Diameter

• Measure the inner diameter of valve guide with bore gauge.

  Standard

  : Refer to Cylinder Head .

Valve Guide Clearance

• (Valve guide clearance) = (Valve guide inner diameter) - (Valve stem diameter)

  Standard

  : Refer to Cylinder Head .

• If the calculated value exceeds the limit.
  • Replace valve (EXH) and/or valve guide (EXH). Refer to Exploded View . (Exhaust side)
  • Replace VVEL ladder assembly & cylinder head assembly. Refer to Exploded View . (Intake side)
    NOTE: Since the valve (INT) and valve guide (INT) cannot be replaced by the piece, VVEL ladder assembly & cylinder head assembly replacement are required.

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.

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  A	: OK
  B	: NG

  • If not, grind to adjust valve fitting and check again. If the contacting surface still has "NG" conditions even after the re-check, replace valve seat (EXH). Refer to Exploded View . (Exhaust side)
  • If not, replace VVEL ladder assembly & cylinder head assembly. Refer to Exploded View . (Intake side)
    NOTE: Since the valve seat (INT) cannot be replaced by the piece, VVEL ladder assembly & cylinder head assembly replacement are required.

Valve Spring (with valve spring seat) Squareness 

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

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  B

  : Contact

  Limit

  : Refer to Cylinder Head .

• If it exceeds the limit.
  • Replace valve spring (with valve spring seat) (EXH). Refer to Exploded View . (Exhaust side)
  • Replace VVEL ladder assembly & cylinder head assembly. Refer to Exploded View . (Intake side)
    NOTE: Since the valve spring (with valve spring seat) (INT) cannot be replaced by the piece, VVEL ladder assembly & cylinder head assembly replacement are required.

Valve Spring Dimensions and Valve Spring Pressure Load 

• Check the valve spring (with valve spring seat) pressure at specified spring height.

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  Standard

  : Refer to Cylinder Head .

• If the installation load or load with valve open is out of the standard.
  • Replace valve spring (with valve spring seat) (EXH). Refer to Exploded View . (Exhaust side)
  • Replace VVEL ladder assembly & cylinder head assembly. Refer to Exploded View . (Intake side)
    NOTE: Since the valve spring (with valve spring seat) (INT) cannot be replaced by the piece, VVEL ladder assembly & cylinder head assembly replacement are required.