MBE 900

Section 1.18 Valve Seats and Guides

Section 1.18
Valve Seats and Guides

Section 1.18.1
Valve Seat Insert Removal

Remove valve seat inserts as follows:‪

  1. Remove the valves. Refer to "1.17.5 Valve Removal" .
  2. Remove the fuel injection nozzle holders. Refer to "2.3.1 Nozzle Holder Removal" .
  3. Clamp the cylinder head on a valve assembly stand.
  4. Locate the point where the groove is to be ground.
    1. Using a measuring device such as calipers, measure the depth of the valve seat bore. See Figure "Critical Dimensions, Valve Seats" . Listed in Table "General Specifications" are the specifications.
      Click to see this graphic in a separate window

      Figure 1. Critical Dimensions, Valve Seats

      Description‪

      Specification‪

      mm (in.)‪

      Valve Seat Interference Fit‪

      0.045-0.080‪

      (0.0018-0.0031)‪

      Depth of Bore in Cylinder Head (see Figure , E)‪

      11.4-11.6‪

      (0.449-0.457)‪

      Height of Valve Seat Insert (see Figure , C)‪

      Intake‪

      7.6-7.7‪

      (0.299-0.303)‪

      Exhaust‪

      8.0-8.1‪

      (0.315-0.319)‪

      Clearance Between Head mating Surface and Valve Seat Insert Face‪

      (see Figure , D)‪

      Intake‪

      3.7-4.0‪

      (0.146-0.157)‪

      Exhaust‪

      3.3-3.6‪

      (0.130-0.142)‪

      Table 1. General Specifications
    2. Measure the distance from the surface of the cylinder head to the point on the valve seat insert where the groove is to be ground.

      Note: This point should be approximately 1.50 mm (0.060 in.) below any angular valve seating face on the valve seat insert.

  5. Groove the valve seat insert for ease of removal.
    1. Install the grinder base on the grinder from the valve seat removal kit (PT-6390) . Adjust the grinding wheel to the proper height, 1.50 mm (0.060 in.). See Figure "Adjusting the Grinding Wheel" .
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       1. Grinder‪

       3. Measuring Device‪

       2. Grinding Wheel‪

      Figure 2. Adjusting the Grinding Wheel

    2. Select the appropriate size grinding wheel from those included in the kit, based on the distance, as measured. Secure the grinder base to the grinding wheel by tightening the set screw.

      Note: Two sizes of grinding wheels are available (1.250 in. diameter and 0.750 in. diameter). To make any wheel smaller, use the dressing stone included in the kit. The dressing stone can also be used to keep the wheels sharp, which increases cutting speed. When dressing a worn wheel, make the edge of the wheel just slightly wider than the width of the steps on the extractors.

    3. Grind a groove around the inside circumference of the valve seat insert. Make the groove approximately 0.75 mm (0.030 in.) deep on a side. See Figure "Grinding the Groove" .
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       1. Pressure Hose‪

       3. Cylinder Head‪

       2. Grinder‪

      Figure 3. Grinding the Groove

  6. Assemble the valve seat remover, using the tools from the valve seat removal kit.
    1. Attach the crank handle onto the threaded shaft assembly.
    2. Select an extractor from the valve seat removal kit. Use the extractor with the largest step that will fit into the inside diameter of the valve seat insert.
    3. Install the extractor on the threaded shaft assembly. See Figure "Installing the Extractor" .
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       1. Extractor Shaft‪

       2. Step‪

      Figure 4. Installing the Extractor

    4. Position the extractor step in the groove in the valve seat insert. Turn the T-handle on the threaded shaft to fully expand the extractor. See Figure "Turning the T-Handle" .
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       1. T-Handle‪

       3. Extractor‪

       2. Threaded Shaft‪

      Figure 5. Turning the T-Handle

      Note: Use only moderate force to expand the extractor.

    5. Install the lifting bridge over the extractor. See Figure "Installing the Lifting Bridge" .
    6. Click to see this graphic in a separate window

       1. T-Handle‪

       3. Lifting Bridge‪

       2. Crank Handle‪

       4. Extractor‪

      Figure 6. Installing the Lifting Bridge

  7. Remove the valve seat insert.
    1. Turn the crank handle to remove the insert from the valve seat bore.
    2. To release the insert from the extractor, turn the T-handle on the threaded shaft.
  8. Measure the valve seat bore. See Figure "Measuring the Valve Seat Bore" . If the bore is not within specifications, it must be machined to the next repair stage. Refer to "1.18.1.1 Valve Seat Bore Cleaning and Machining" .
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     1. Measuring Device‪

     2. Valve Seat Bore‪

    Figure 7. Measuring the Valve Seat Bore

  9. Repeat this procedure for each valve seat insert.
Section 1.18.1.1
Valve Seat Bore Cleaning and Machining

Clean and machine the valve seat bore as follows:‪

  1. Clean the valve seat bore and surrounding area of dirt, debris, and metal chips.
  2. Insert the correct pilot into the valve guide. See Figure "Installing the Pilot in the Valve Guide" . Tighten the pilot in place.
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    Figure 8. Installing the Pilot in the Valve Guide

    NOTICE:

    Install the machining tool carefully in order to avoid damage to the cutter or the head.‪

  3. Install the machining tool.
    1. Coat the pilot lightly with oil.
    2. Position the machining tool over the pilot and move the machining tool in a horizontal direction until it is beyond the bore diameter.
    3. Push the machining tool down until the cutter rests on the head surface.
    4. Push the pilot shaft down until it rests on the pilot.
    5. Raise the machining tool until the cutter clears.
  4. Set the cutting depth. The cutting depth should be equal to the depth of the bore. See Figure "Critical Dimensions, Valve Seats" .

    Note: Dimensions A and B are listed in Table "Repair Stage Specifications" ; dimensions C, D, and E are listed in Table "General Specifications" .

    Click to see this graphic in a separate window

    Figure 9. Critical Dimensions, Valve Seats

  5. Measure the height of the valve seat insert. See Figure "Measuring the Height of the Valve Seat Insert" .
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     1. Valve Seat Insert‪

     2. Measuring Device‪

    Figure 10. Measuring the Height of the Valve Seat Insert

  6. Measure the outside diameter of the valve seat insert. See Figure "Measuring the Outside Diameter of the Valve Seat Insert" .
    Click to see this graphic in a separate window

     1. Valve Seat Insert‪

     2. Measuring Device‪

    Figure 11. Measuring the Outside Diameter of the Valve Seat Insert

  7. Calculate the machining adjustment. See Figure "Determining the Machining Adjustment" .
    Click to see this graphic in a separate window

     1. Pilot Shaft Diameter (P)‪

     2. Machining Adjustment (M)‪

    Figure 12. Determining the Machining Adjustment

    1. Read the value for the valve seat basic bore (dimension "A" listed in Table "Repair Stage Specifications" ).
    2. Repair Stage‪

      Basic Bore in Cylinder Head‪

      (see Figure , A)‪

      Outside Diameter of Valve Seat Insert‪

      (see Figure , B)‪

      Intake‪

      mm (in.)‪

      Exhaust‪

      mm (in.)‪

      Intake‪

      mm (in.)‪

      Exhaust‪

      mm (in.)‪

      Standard‪

      35.000–35.025‪

      (1.378–1.379)‪

      40.000–40.025‪

      (1.575–1.576)‪

      35.07–35.08‪

      (1.3807–1.3811)‪

      40.07–40.08‪

      (1.5775–1.5779)‪

      Standard I‪

      35.300–35.325‪

      (1.390–1.391)‪

      40.300–40.325‪

      (1.575–1.588)‪

      35.37–35.38‪

      (1.3925–1.3929)‪

      40.37–40.38‪

      (1.5893–1.589)‪

      Stage I‪

      35.500–35.525‪

      (1.398–1.399)‪

      40.500–40.525‪

      (1.594–1.595)‪

      35.57–35.58‪

      (1.4004–1.4008)‪

      40.57–40.58‪

      (1.5972–1.5976)‪

      Table 12. Repair Stage Specifications

      Note: Choose the repair stage corresponding to the size of the outside diameter of the valve seat insert (dimension "B" listed in Table "Repair Stage Specifications" ), as measured in the previous step.

    3. Measure the diameter of the pilot (P). See Figure "Determining the Machining Adjustment" .
    4. Add the diameter of the pilot to the valve seat bore and divide by two. Use this formula: M = (A + P)/2. Example: If the valve seat bore is 1.378 inches, and the diameter of the pilot is 0.573 inches, M = (1.378 + 0.573)/2 = 1.951/2 = 0.976 inches.
  8. Set a micrometer to dimension "M" as calculated in the previous step. Lift the machining tool slightly and place the micrometer on the pilot. Set the cutter at dimension "M" and lock it in place.

    Note: For the first cut, it is recommended that the adjustment of the cutter be set at 0.1 mm (0.004 inch) less than the finished dimension (dimension "A" listed in Table "Repair Stage Specifications" ).

  9. Machine the valve seat bore. Continue machining until the finished dimension is reached.
    1. Adjust the cutter as often as is necessary to reach the finished dimension.
    2. Without additional adjustment, turn the cutter through one more time.
  10. Lift the machining tool slightly and machine the face of the valve seat bore. See Figure "Critical Dimensions, Valve Seats" , D. Check the clearance between the head mating surface and the face of the valve seat insert. The specifications for intake and exhaust valves are listed in Table "General Specifications" .

    Description‪

    Specification‪

    mm (in.)‪

    Valve Seat Interference Fit‪

    0.045-0.80‪

    (0.0018-0.0031)‪

    Depth of Bore in Cylinder Head (see Figure , E)‪

    11.4-11.6‪

    (0.449-0.457)‪

    Height of Valve Seat Insert (see Figure , C)‪

    Intake‪

    7.6-7.7‪

    (0.299-0.303)‪

    Exhaust‪

    8.0-8.1‪

    (0.315-0.319)‪

    Clearance Between Head mating Surface and Valve Seat Insert Face‪

    (see Figure , D)‪

    Intake‪

    3.7-4.0‪

    (0.146-0.157)‪

    Exhaust‪

    3.3-3.6‪

    (0.130-0.142)‪

    Table 13. General Specifications
  11. Remove the cutting tool and measure the outside diameter of the valve seat insert. See Figure "Measuring the Outside Diameter of the Valve Seat Insert" . There must be an interference fit of 0.045 to 0.080 mm (0.0018 to 0.0031 in.) between the valve seat insert and the bore.
  12. Install the valve seat inserts. Refer to "1.18.2 Valve Seat Insert Installation" .

Section 1.18.2
Valve Seat Insert Installation

Install the valve seat inserts as follows:‪

warning

FREEZING OR SUFFOCATION

To avoid injury from freezing or suffocation when using liquid nitrogen, wear a face shield and protective clothing and work in a well ventilated area.‪

Note: Do not touch the insert with your bare hands. Handle the inserts with tweezers.

  1. Place the valve seat inserts in liquid nitrogen. Allow the inserts to cool approximately 20 to 30 minutes.

    Note: Liquid nitrogen is commercially available.

    warning

    BURNS

    To avoid injury from burning, use lifting tools and heat-resistant gloves when handling heated components.‪

  2. Heat the head to approximately 80°C (176°F) in a hot water tank. Remove the head from the hot water tank using an overhead hoist and place the head on a workbench or stand. Wear insulated gloves when handling the heated head.
  3. Carefully remove the valve seat inserts from the liquid nitrogen and place the inserts in the bores of the heated head. See Figure "Positioning a Valve Seat Insert" .
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    Figure 13. Positioning a Valve Seat Insert

  4. Drive in each insert, using a suitable driver. See Figure "Driving a Valve Seat Insert Into Place" .
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    Figure 14. Driving a Valve Seat Insert Into Place

  5. Machine the inserts to specifications. Refer to "1.18.2.1 Valve Seat Insert Machining" .
  6. Install the fuel injection nozzle holders. Refer to "2.3.2 Nozzle Holder Installation" .
  7. Install the valves. Refer to "1.17.6 Valve Installation" .
Section 1.18.2.1
Valve Seat Insert Machining

Machine valve seat inserts as follows:‪

Note: Perform this operation with the valve guides installed.

  1. Measure the outside diameter of the valve seat. See Figure "Measuring the Valve Seat Outside Diameter" .
    Click to see this graphic in a separate window

     1. Measuring Device‪

     2. Valve Seat Bore‪

    Figure 15. Measuring the Valve Seat Outside Diameter

    Note: If the valve seats show only slight imprinting from the valves, the seats can be machined without replacing the valve seat inserts, as long as the maximum valve face recess does not exceed 1.5 mm (0.059 in.).

  2. Insert the correct pilot into the valve guide. See Figure "Installing the Pilot in the Valve Guide" . Tighten the pilot in place.
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    Figure 16. Installing the Pilot in the Valve Guide

  3. Secure the machining tool on the support.

    Note: Be sure that the machining tool is mounted with the correct angle adjustment of 20 degrees for the intake valve seat, or 45 degrees for the exhaust valve seat as listed in Table "Valve Seat Specifications" .

    Description‪

    Intake‪

    mm (in.)‪

    Exhaust‪

    mm (in.)‪

    Valve Seat Angle‪

    (see Figure , A)‪

    20 degrees‪

    45 degrees‪

    Valve Seat Width at Valve Seat Insert‪

    (see Figure , B)‪

    1.5-2.5‪

    (0.059-0.098)‪

    1.8-3.0‪

    (0.071-0.118)‪

    Valve Seat Diameter at Insert‪

    (see Figure , C)‪

    31.0‪

    (1.22)‪

    36.0‪

    (1.42)‪

    Machining Dimension‪

    (see Figure , E)‪

    4.2-4.4‪

    (0.165-0.173)‪

    4.3-4.5‪

    (0.169-0.177)‪

    Table 17. Valve Seat Specifications
  4. Coat the pilot lightly with oil. Insert the machining tool onto the pilot and press the tool down until the cutter rests on the cylinder head surface.
  5. Position the machining tool over the pilot. Center the cutter over the valve seat insert.

    NOTICE:

    Do not allow the cutter to strike the cylinder head. This will damage the carbide metal tip of the cutting blade.‪

  6. Lower the cutter until it is touching the middle of the valve seat insert.
  7. Press the pilot shaft down until it seats on the pilot.
  8. Using a marking pen, mark the valve seat insert every 120 degrees. See Figure "Mark the Valve Seat Insert" .
    Click to see this graphic in a separate window

     1. Valve Seat Insert‪

    Figure 17. Mark the Valve Seat Insert

  9. Set the cutter against the inner edge of the seat and lock it in place. Do not feed the tool beyond this setting yet.
  10. Machine the valve seat insert along its inner edge. The cut in the metal will generally be uneven at this time. Adjust the cutter as often as necessary to meet the finished dimensions.
  11. Repeat the machining procedure until the seat is thoroughly clean. Do not exceed the machining limits for the valve seat diameter and width (see Figure "Intake and Exhaust Valve Seat Cross Sections" , C and B) listed in Table "Valve Seat Specifications" . When the seat is clean, make one more full turn with the cutter without further adjustment.

    Note: If new valve seat inserts have been installed, be sure they meet the specifications listed in Table "Valve Seat Specifications" .

    Click to see this graphic in a separate window

    Figure 18. Intake and Exhaust Valve Seat Cross Sections

  12. Machine the valve seat insert along its outer edge. The cut in the metal will generally be uneven at this time. Adjust the cutter as often as necessary to meet the finished dimensions.
  13. Repeat the machining procedure until the seat is thoroughly clean. Do not exceed the machining limits for the valve seat diameter and width (see Figure "Intake and Exhaust Valve Seat Cross Sections" , C and B) listed in Table "Valve Seat Specifications" . When the seat is clean, make one more full turn with the cutter without further adjustment.

    Note: If new valve seat inserts have been installed, be sure they meet the specifications listed in Table "Valve Seat Specifications" .

  14. Install the valves. Refer to "1.17.6 Valve Installation" .
  15. Install the cylinder head. Refer to "1.2.2 Cylinder Head Installation" .

Section 1.18.3
Valve Guide Removal

Remove the valve guides as follows:‪

  1. Remove the cylinder head. Refer to "1.2.1 Cylinder Head Removal" .
  2. Remove the valves. Refer to "1.17.5 Valve Removal" .
  3. Secure the cylinder head in a vise.
  4. Using the go/no go gauge J-46396 , try to insert it into the valve guide. The smaller diameter end of the gauge should fit into the guide. If the larger diameter end fits in either side of the guide, replace the guide. See Figure "Insert the Go/No Go Gauge" .
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     1. Valve Guide‪

     2. Go/No Go Gauge‪

    Figure 19. Insert the Go/No Go Gauge

  5. Drive the valve guides out of the head from the combustion side using the valve guide remover J-46397 . See Figure "Removing the Valve Guides" .
    Click to see this graphic in a separate window

     1. Valve Guide Remover‪

     2. Valve Bore‪

    Figure 20. Removing the Valve Guides

  6. Measure the valve guide bore in the cylinder head. See Figure "Measure the Valve Guide Bore" .
    Click to see this graphic in a separate window

     1. Cylinder Head‪

     2. Valve Seat Insert‪

    Figure 21. Measure the Valve Guide Bore

    1. Insert the gauge into the bore and adjust it until the telescoping tips are firm against the walls of the bore.
    2. Tighten the gauge.
    3. Using a measuring device such as calipers or a micrometer, read the measurement off the tips of the gauge. See Figure "Reading the Bore Measurement" .

      Note: Measure the telescoping bore gauge from tip to tip.

      Click to see this graphic in a separate window

       1. Measuring Device‪

       2. Telescoping Bore Gauge‪

      Figure 22. Reading the Bore Measurement

    4. If the measurement is not within the specifications listed in Table "Repair Stage Specifications" and shown in see Figure "Cylinder Head Cross Section" , machine the cylinder head valve guide bore.
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       1. Valve Guide‪

       2. Cylinder Head‪

      Figure 23. Cylinder Head Cross Section

      Repair Stage‪

      Valve Guide Outside Diameter‪

      (see Figure , A1)‪

      Bore in Cylinder Head‪

      (see Figure , A)‪

      mm (in.)‪

      mm (in.)‪

      Standard‪

      14.028-14.046‪

      (0.552-0.553)‪

      14.000-14.018‪

      (0.551-0.552)‪

      Standard I‪

      14.228-14.246‪

      (0.560-0.561)‪

      14.200-14.218‪

      (0.559-0.560)‪

      Table 25. Repair Stage Specifications

      Note: For standard bores, use the 14.0 mm reamer and ream the bore to the Standard specifications listed in Table "Repair Stage Specifications" . For oversize bores, use the 14.2 mm reamer and ream the bore to the Standard I specifications. Turn the reamer only in a clockwise direction.

  7. Using the 14.0 or 14.2 mm reamer J-46394 , ream the valve guide bore in the cylinder head. See Figure "Ream the Valve Guide Bore" .
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     1. Reamer‪

    Figure 24. Ream the Valve Guide Bore

  8. After reaming, clean the cylinder head to remove metal shavings.

Section 1.18.4
Valve Guide Installation

Install the valve guides as follows:‪

warning

FREEZING OR SUFFOCATION

To avoid injury from freezing or suffocation when using liquid nitrogen, wear a face shield and protective clothing and work in a well ventilated area.‪

Note: Do not touch the valve guide with bare hands.

  1. Place the valve guide in liquid nitrogen. Allow the valve guide to cool about 20 to 30 minutes.
  2. Using pliers, remove the valve guide from the cooling box.
  3. Fit the valve guide adapter J-46404 onto the valve guide installer J-46402 . See Figure "Guide Installer Adaptor" .
    Click to see this graphic in a separate window

     1. Valve Guide‪

    Figure 25. Guide Installer Adaptor

    Note: The guide installer adaptor has a different machined depth on each end. Use the end marked "14.5" for intake valve guides and "18.0" for exhaust valve guides.

  4. Coat the new valve guide with graphite oil and drive it into the bore using the valve guide installer J-46402 and the guide installer adapter J-46404 . See Figure "Driving the Valve Guide into the Bore" .
    Click to see this graphic in a separate window

     1. Hammer‪

     2. Valve Guide‪

    Figure 26. Driving the Valve Guide into the Bore

  5. Check the valve guide protrusion from the spring surface (from the base relative to the top edge of the valve guide). See Figure "Cylinder Head Cross Section" , D. The valve guide protrusion specifications are listed in Table "Valve Guide Specifications" .
    Click to see this graphic in a separate window

     1. Valve Guide‪

     2. Cylinder Head‪

    Figure 27. Cylinder Head Cross Section

    Description‪

    Specification‪

    mm (in.)‪

    Valve Guide Inside Diameter, Intake and Exhaust (see Figure , B)‪

    8.000-8.022 (0.315-0.316)‪

    Valve Guide Length, Intake and Exhaust (see Figure , C)‪

    60.000-60.30 (2.36-2.37)‪

    Valve Guide Protrusion from the Spring Surface‪

    (see Figure , D)‪

    Intake‪

    13.7-14.5 (0.539-0.571)‪

    Exhaust‪

    17.2-18.0 (0.677-0.709)‪

    Valve guide Overlap in Cylinder Head‪

    0.010-0.046 (0.0004-0.0018)‪

    Table 31. Valve Guide Specifications
  6. Using the valve guide reamer J-46395 , ream the inside diameter of the valve guide. See Figure "Cylinder Head Cross Section" , B. The inside diameter of the valve guide is listed in Table "Valve Guide Specifications" .

    Note: Turn the reamer only in a clockwise direction.

  7. After reaming, clean the cylinder head to remove metal shavings.
  8. Install the valves. Refer to "1.17.6 Valve Installation" .
  9. Install the cylinder head. Refer to "1.2.2 Cylinder Head Installation" .


MBE 900 Service Manual - 6SE414
Generated on 10-13-2008

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