Cummins/Onan — Injector Plunger Adjustment Using Torque Method (V/VT-378, V/VT-504, V/VT-555)
Adjustments · Injectors
From a Cummins/Onan owner's manual covering: KT38, KTA19, Kt19, KtA38, KtA50, N-855, NH-672, NH-743, NH-855, NT-855, NTA-855, NTC-270…. Check it applies to your exact model before use.
Applies to: Cummins/Onan Kt19, Cummins/Onan KTA38, Cummins/Onan KTA50
Before you start
- Use only proper engine barring techniques; do not attempt to rotate the engine by pulling or prying on the fan.
Procedure
- Turn the crankshaft in direction of rotation until the No. 1 'VS' mark appears; verify both intake and exhaust valves are closed for cylinder No. 1.
- Tighten the injector hold-down capscrew to 30 to 35 ft-lbs [41 to 47 N·m].
- Turn the adjusting screw down until the plunger contacts the cup and advance an additional 15 degrees to squeeze the oil from the cup.
- Loosen the adjusting screw one turn; tighten with an in-lb torque wrench and screwdriver adapter to the cold-setting value.
- Hold the adjusting screw and tighten the locknut to the specified torque.
- Turn the crankshaft to the next 'VS' mark per firing order and repeat.
Tools required
- Snap-On Model TQ12B or equivalent in-lb torque wrench Amazon
- screwdriver adapter Amazon
- ST-669 Adapter Amazon
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Cold setting 80 in-lbs
- Hot setting 60 in-lbs
- Locknut torque 40 to 45 ft-lbs [54 to 61 N·m]; 30 to 36 ft-lbs [41 to 47 N·m] with ST-669 Amazon eBay $204.59
Full service-parts list: Cummins/Onan Kt19 →, Cummins/Onan KTA38 →, Cummins/Onan KTA50 →
Source: Cummins/Onan owner's 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.