Cummins/Onan — Priming the Lubricating System
Maintenance
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
- Do not prime the engine lubricating system from the by-pass filter.
- Clean the area of any lubricating oil spilled while priming or filling the crankcase.
Procedure
- Fill the crankcase to the 'L' (low) mark on the dipstick.
- Remove the plug from the lubricating oil crossover passage on NH/NT-855 engines, from the head of the lubricating oil filter housing on V engines, or from the front of the oil cooler housing on KT/KTA
- Connect a hand or motor-driven priming pump line from clean lubricating oil to the plug boss in the housing.
- Prime until a 30 psi [207 kPa] minimum pressure is obtained.
- Crank the engine at least 15 seconds with fuel shut-off valve closed, maintaining external oil pressure at a minimum of 15 psi [103 kPa].
- Remove the external oil supply and replace the plug; tighten to proper torque.
- Fill the crankcase to the 'H' (high) mark on the dipstick.
Tools required
- hand or motor-driven priming pump Amazon
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Prime to 30 psi [207 kPa] minimum
- Maintain 15 psi [103 kPa] minimum while cranking
- On turbocharged engines add 2 to 3 oz. [50 to 60 cc] clean lubricating oil to the turbocharger bearing
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.