Detroit Diesel — Adjust Exhaust Valve Clearance (Two Valve Cylinder Head)
Adjustments
From a Detroit Diesel service manual — check it applies to your exact model before use.
Before you start
- If a wrench is used on the crankshaft bolt do not turn the engine in a left-hand direction of rotation.
Procedure
- Place the speed control lever in idle; secure the stop lever in no-fuel position.
- Remove the valve rocker cover(s).
- Rotate the crankshaft until the injector follower is fully depressed on the cylinder to be adjusted.
- Loosen the exhaust valve rocker arm push rod lock nut.
- Place a .012 in feeler gage J 9708 between valve stem and rocker arm and adjust the push rod for a smooth pull.
- Hold the push rod with a 5/16 in wrench and tighten the lock nut with a 1/2 in wrench.
- Recheck: the .010 in gage passes freely and the .012 in does not.
- Adjust the remaining valves the same way.
- At normal operating temperature recheck: the .008 in gage passes and the .010 in does not.
Tools required
- Feeler gage J 9708 Amazon
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Cold setting .012 in (0.010 in passes, 0.012 in does not)
- Hot setting .008 in (0.008 in passes, 0.010 in does not)
- Normal operating temperature 160-185 F (71-85 C)
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.