Detroit Diesel — Checking of Valve Lift
Testing & diagnosis · Valvetrain/Camshaft
From a Detroit Diesel service manual — check it applies to your exact model before use.
Before you start
- If the gauge reading fails to reach specification, be sure the valves were completely open; the dial gauge shows the highest reading when the valve is completely open.
Procedure
- Remove the cylinder head cover(s).
- Install the engine barring tool J-46392 in the flywheel housing.
- Rotate the flywheel until the piston in the selected cylinder is at ignition TDC.
- Adjust the valve lash.
- Mount a dial gauge on the valve bridge with approximately 15 mm (0.60 in.) preload.
- Set the dial gauge to zero and rotate the flywheel counterclockwise.
- Read the intake valve lift when completely open; must reach at least 11.546 mm (0.4546 in.).
- Move the gauge to the exhaust spring retainer, set zero, and read exhaust valve lift; must reach at least 11.963 mm (0.4710 in.).
- Check the remaining cylinders one at a time.
- Remove the dial gauge and adjust the valves.
- Remove the engine barring tool and install the inspection cover; torque bolts 25 N·m (18 lb·ft).
- Install the cylinder head cover(s).
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Specified dial gauge preload for checking valve lift 15 mm (0.60 in.)
- Valve lift with intake valves completely open 11.546 (at least 0.4546) mm (in.)
- Valve lift with exhaust valves completely open 11.963 (at least 0.4710) mm (in.)
Source: Detroit Diesel service manual. Steps and values are as documented; always cross-check against the official manual and any later revisions for your exact serial number before servicing.