Valve, Valve Guide Inspection

Measure the valve head margin thickness using a vernier caliper.
- If it is less than the standard specification, replace the valve.
Standard valve head margin thickness

IN: 1.75-1.95 mm {0.0689-0.0767 in}

EX: 1.95-2.15 mm {0.0768-0.0846 in}

Fig 1: Valve Head Margin Thickness Specifications
Courtesy of MAZDA MOTORS CORP.
Measure the length of the each valve using a vernier caliper.
- If it is less than the minimum specification, replace the valve.
Standard valve length

IN: 107.00-107.60 mm {4.2127-4.2362 in}

EX: 117.09-117.69 mm {4.6099-4.6334 in}

Minimum valve length

IN: 106.78 mm {4.2039 in}

EX: 116.87 mm {4.6012 in}.

Fig 2: Measuring Length Of Valve Using Vernier Caliper
Courtesy of MAZDA MOTORS CORP.
Measure the valve stem diameter of each valve using the micrometer. Measurement positions total six and are in the X and Y directions, at three points (A, B, and C) as shown in the figure.
- If it is less than the minimum specification, replace the valve.
Standard valve stem diameter

IN: 5.470-5.485 mm {0.2154-0.2159 in}

EX: 5.465-5.480 mm {0.2152-0.2157 in}

Minimum valve stem diameter

IN: 5.424 mm {0.2135 in}

EX: 5.419 mm {0.2133 in}

Fig 3: Measuring Point For Valve Stem Diameter Of Valve
Courtesy of MAZDA MOTORS CORP.
Measure the inner diameter of each valve guide using the caliper gauge. Measurement positions total six and are in the X and Y directions, at three points (A, B, and C) as shown in the figure.
- If it is not within the specification, replace the valve guide.
Standard valve guide inner diameter

IN: 5.510-5.530 mm {0.2170-0.2177 in}

EX: 5.510-5.530 mm {0.2170-0.2177 in}

Fig 4: Measuring Inner Diameter Of Valve Guide Using Caliper Gauge
Courtesy of MAZDA MOTORS CORP.
Calculate the clearance between the valve stem and the valve guide by subtracting the inner diameter of the valve guide from the outer diameter of the corresponding valve stem.
- If it exceeds the maximum specification, replace the valve or valve guide.
Standard clearance between valve stem and guide

IN: 0.025-0.060 mm {0.0010-0.0023 in}

EX: 0.030-0.065 mm {0.0012-0.0025 in}

Fig 5: Checking Clearance Between Valve Stem And Valve Guide
Courtesy of MAZDA MOTORS CORP.

Maximum clearance between valve stem and guide 0.10 mm {0.0039 in}
Measure the projection height (dimension A) of each valve guide using the vernier caliper.
- If it is not within the specification, replace the valve guide.
Standard valve guide projection height

IN: 16.4-17.0 mm {0.646-0.669 in}

EX: 16.4-17.0 mm {0.646-0.669 in}

Fig 6: Measuring Projection Height (Dimension A) Of Valve Guide Using Vernier Caliper
Courtesy of MAZDA MOTORS CORP.