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Detroit Diesel S50 Engine

The Detroit Diesel S50 is a 8.5 L 6-cylinder turbocharged, intercooled engine rated at 1800 rpm, producing up to 156 kW. It powers generator sets from Cummins/Onan, including the 4D6. It holds 6.8 L (1.8 gal) of oil and 9.2 L (2.4 gal) of coolant.

Also known as: Detroit Diesel S50

8.5 L
Displacement
6
Cylinders
1800 rpm
Rated speed
156 kW
Gross power
On this pageSpecsGenerator setsMaintenanceFAQ

Engine specifications

Oil capacity6.8 L
Coolant capacity9.2 L
Displacement8.5 L
Cylinders6
Aspirationturbocharged, intercooled
Rated speed1800 rpm
Gross power156 kW

Common problems

15
  • Voltage potentiometer out of setting.
    Fix: Reset voltage.
  • Unstable voltage
    Cause: Speed variation in engine.
    Fix: Check regularity of rotation.
  • Speed variation in engine.
    Fix: Check regularity of rotation.
  • Regulator out of setting.
    Fix: Regulate stability of regulator by acting on “STABILITY” potentiometer.
  • No residual voltage.
    Fix: For an instant apply on the + and – terminals of the electronic regulator a 12 V battery voltage with a 30 Ω resistor in series respecting the polarities.
  • Lower than rated voltage at load
    Cause: Intervention by protection.
  • Low voltage at no load
    Cause: Intervention of protection.
    Fix: Check rpm.
  • Insufficient residual voltage.
    Fix: Increase the speed by 15 %.
  • Higher than rated voltage at load
    Cause: Voltage potentiometer out of setting.
    Fix: Reset voltage potentiometer.
  • High voltage at no load
    Cause: Failed regulator.
    Fix: Substitute regulator.
  • Engine runs in idle speed
    Cause: No SAPE connected.
    Fix: Put single/parallel switch in single position.
  • Current too high, power factor lower than 0.8; speed lower than 10 % of rated speed
    Cause: Failed regulator.
    Fix: Substitute regulator.
  • Connections are interrupted.
    Fix: Check connection cables as per attached drawings.
  • Blown fuse.
    Fix: Replace fuse.
  • Alternator does not excite Blown fuse.
    Fix: Replace fuse.

Compiled from service & troubleshooting documentation across every generator set that uses the Detroit Diesel S50.

Maintenance schedule

ItemSpecCapacityPart #Interval
Air filterClean/Replace—2000 hr
Fuel filterReplace—500 hr
Oil filterReplace—2000 hr
BatteryReplace—500 hr
BeltReplace—2000 hr
CoolantCheck/Clean9.2—500 hr
OilHigh-quality, mineral, hydraulic or synthesized hydrocarbon oil with rust and oxidation inhibitors, anti-foam and anti-wear properties is recommended.6.8—2000 hr
Spark plugCheck/Replace—2000 hr

Pooled from every document that names this exact engine — confirm the interval and part number against your unit's serial number.

Common questions

What is the oil capacity of the Detroit Diesel S50?

The Detroit Diesel S50 engine has an oil capacity of 6.8 liters.

What is the displacement of the Detroit Diesel S50?

The Detroit Diesel S50 has a displacement of 8.5 liters with 6 cylinders.

Which generators use the Detroit Diesel S50 engine?

The Detroit Diesel S50 powers 1 generator set(s), including Cummins/Onan 4D6.

How often should you change the oil in the Detroit Diesel S50?

The Detroit Diesel S50 oil change interval is every 2000 hours.

What is a common problem with the Detroit Diesel S50 engine?

A commonly reported issue on generators using the Detroit Diesel S50 is: Voltage potentiometer out of setting.. Fix: Reset voltage..