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Home›Engines›Kohler 1.9L

Kohler 1.9L Engine

The Kohler 1.9L is a 1.9 L engine. It powers generator sets from Kohler, including the 175REOZT4, 35 REOZT4 and 45 REOZT4.

Also known as: KOHLER® 1.9L

1.9 L
Displacement
On this pageSpecsGenerator setsFAQService intervalsTorque & specsProcedures

Engine specifications

Displacement1.9 L

Common problems

6
  • Emergency Stop 32A
    Fix: Reset the emergency stop switch.
  • Pre Low Oil Pressure 41
    Fix: Check and adjust oil level or replace oil pump.
  • Pre High Coolant Temp. 40
  • Low Fuel 63
    Fix: Refuel the generator set.
  • Low Battery Volts 62
  • High Coolant Temperature 32

Compiled from service & troubleshooting documentation across every generator set that uses the Kohler 1.9L.

Service intervals

2
ItemActionHoursMonthsNotes
Paralleling boxInspect12 moAnnually by a Kohler authorized distributor/dealer, or when wear, damage, deterioration, or malfunction is evident or suspected.
Paralleling box internal componentsInspect1 moMonthly or when a condition noticed during external inspection may have affected internal components; enclosure cover must be removed by trained personnel.

Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.

Service specifications

26
TypeItemValueUnitCondition
GapSpeed sensor air gap0.36- 0.71mm
OtherEngine speed adjustment50default setting; settings between 40 and 60 acceptable; 52 increases speed by 2 RPM, 49 decreases by 1 RPM
OtherGenerator to bus phase angle-10 to 10degreesverify with contactor closed
OtherReactive droop1%default setting; range 0.5 - 2%
PressureBattery equalizer input voltage (24 volts nominal)20- 35volts
PressureBattery equalizer output voltage(input voltage/2) ±2%volts
PressurePressure switch 364345483 ±14kPa
ResistancePressure sender 264390 value A240 +17/- 15ohms at 0 psi
ResistancePressure sender 264390 value B153 +12/- 15ohms at 25 psi
ResistancePressure sender 264390 value C33.5ohms at 100 psi
ResistancePressure sender 365624 value A241 ±16ohms at 0 psi
ResistancePressure sender 365624 value B152 ±13ohms at 50 psi
ResistancePressure sender 365624 value C33.5ohms at 200 psi
ResistanceTemperature sender 226717 value A123.8 +7.2/- 7.8ohms at 90.6 C (195 F)
ResistanceTemperature sender 226717 value B35.6 +3.4/- 3.6ohms at 137.8 C (280 F)
ResistanceTemperature sender 226919 value A942 ±22ohms at 37.7 C (100 F)
ResistanceTemperature sender 226919 value B35ohms at 115.6 C (240 F)
SpeedOverspeed shutdown70Hz60 Hz models
TemperatureBattery equalizer operating temperature- 40 to 71C (- 40 F to 160 F)
TemperatureTemperature switch 241308107 ±4C (225 F ±7 F)normally open to close on temp. rise
TemperatureTemperature switch 290090/GM5170516 ±3C (60 F ±5 F)normally open to close on temp. fall
TorquePGEN terminal block connections0.5Nm
TorquePGEN terminal block connections4.4in. lbs.
VoltageController measurement accuracy2%without calibration; requires a calibrated multimeter for calibration
VoltageSpeed sensor voltage, wire 2 (black) & 16 (white)3- 6volts DC
VoltageSpeed sensor voltage, wire 2 (black) & 24 (red)8- 10volts DC

Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.

Procedures

12
Calibration adjustment

⚠ Copying personality profiles from one controller to another can overwrite calibration coefficients and requires re-calibration.

Tools: Calibrated multimeter with recent calibration verification

  1. Use a calibrated multimeter to measure the generator voltage and enter the correct value in the CONTROLLER CONFIG -> CALIBRATION screen.
  2. Use a calibrated multimeter to measure the bus voltage and enter the correct value in the CONTROLLER CONFIG -> CALIBRATION screen.
Overfrequency Adjustment (Over/Underfrequency Relay, Decision-Maker 3+) adjustment
  1. Turn the overfrequency adjustment potentiometer fully clockwise (CW).
  2. Place master switch in RUN to start the generator set.
  3. Adjust governor per engine operation manual, engine service manual, or governor section of this manual.
  4. Slowly turn overfrequency potentiometer counterclockwise (CCW) until the LED starts flashing; after about 10 seconds the set shuts down on auxiliary fault.
  5. Place master switch to OFF/RESET to reset the controller.
  6. Place master switch to RUN to start the generator set.
  7. Readjust the governor to the desired frequency as required.
  8. Place master switch to OFF/RESET to stop the generator set.
Overvoltage Feature Testing and Adjustment (Decision-Maker 3+) adjustment

⚠ Hazardous voltage. Moving parts. Will cause severe injury or death. Operate the generator set only when all guards and electrical enclosures are in place.

⚠ Disconnecting the electrical load. Hazardous voltage will cause severe injury or death.

  1. Disconnect generator set from load by opening line circuit breaker or disconnecting and taping output leads.
  2. Determine overvoltage shutdown value based on user requirement; factory setting is 15% above nominal line-to-neutral voltage.
  3. Remove the controller cover.
  4. Place master switch in RUN to start the generator set.
  5. Observe AC voltmeter; turn voltage adjustment potentiometer CW until generator set shuts down.
  6. If the shutdown point is correct, go to step 12; otherwise continue.
  7. Turn controller circuit board R42 adjustment potentiometer fully CW.
  8. Place master switch to OFF/RESET to reset; then to RUN to start.
  9. Observe AC voltmeter while turning voltage adjustment potentiometer to desired overvoltage shutdown point.
  10. Turn R42 adjustment potentiometer slowly CCW until the generator set shuts down.
  11. Turn controller voltage adjustment potentiometer slightly CCW.
  12. Place master switch OFF/RESET then RUN to start; adjust for correct voltage and phase.
  13. Place master switch OFF/RESET to stop.
  14. Disconnect battery negative lead first; reconnect generator set to load; reconnect battery negative lead last.
Reactive Droop Compensator Adjustment Procedure adjustment

Tools: Voltmeter, Wattmeter

  1. Remove any load; start each generator set with master switch in RUN.
  2. Set reactive droop compensator rheostat on generator set no. 1 to minimum CCW; record rpm/frequency and voltage at 1/4 load steps to full load.
  3. Repeat for generator set no. 2.
  4. Compare readings; adjust voltage within 1 volt and speed within 3 rpm (or 0.1 Hz) at each load step.
  5. Check droop compensation on each unit with an inductive load 1/2 to full load.
  6. Adjust rheostat to approximately 4% below rated voltage at full load.
  7. Repeat for unit no. 2.
Reactive Droop Compensator Alternate Adjustment Procedure adjustment

Tools: Voltmeter

  1. Turn reactive droop compensator rheostat on generator set no. 1 to minimum setting.
  2. Remove controller cover; move voltage sensing lead from V7 to V9 at the AC fuse terminal block.
  3. Remove any load connected to the generator set.
  4. Start the generator set with master switch in RUN.
  5. Use controller or remote voltage adjusting potentiometer to fine adjust voltage.
  6. Apply resistive load (1.0 power factor) until reaching rated current.
  7. Adjust reactive droop compensator rheostat to achieve a 4% droop in voltage.
  8. Remove the resistive load and stop the generator set.
  9. Return voltage sensing lead from V9 to V7 at the AC fuse terminal block.
  10. Replace the controller cover and repeat for generator set no. 2.
Underfrequency Adjustment (Over/Underfrequency Relay, Decision-Maker 3+) adjustment
  1. Turn underfrequency adjustment potentiometer fully clockwise (CW).
  2. Place master switch in RUN to start the generator set.
  3. Adjust governor per engine operation manual, engine service manual, or governor section of this manual.
  4. Slowly turn underfrequency potentiometer counterclockwise (CCW) until LED starts flashing; after about 10 seconds the set shuts down on auxiliary fault.
  5. Place master switch to OFF/RESET to reset the controller.
  6. Place master switch to RUN to start the generator set.
  7. Readjust the governor to the desired frequency as required.
  8. Place master switch to OFF/RESET to stop the generator set.
2-Wire Low Water Level Sender Test diagnostic

⚠ Hot engine and exhaust system can cause severe injury or death. Do not work on the generator set until it cools.

⚠ Hazardous voltage. Moving parts. Will cause severe injury or death. Operate the generator set only when all guards and electrical enclosures are in place.

Tools: DC voltmeter

  1. Measure DC voltage between lead 31A (+) and ground (- ) with sender submerged in coolant; voltmeter indicates approximately 12.5 VDC.
  2. Measure DC voltage between lead 31A (+) and ground (- ) with sender removed from coolant for at least 5-15 seconds; voltmeter indicates a drop to approximately 7 VDC.
3-Wire Low Water Level Sender Test diagnostic

⚠ Hot engine and exhaust system can cause severe injury or death. Do not work on the generator set until it cools.

⚠ Hazardous voltage. Moving parts. Will cause severe injury or death.

Tools: Ohmmeter

  1. Measure resistance between lead 31 and ground with sender submerged in coolant; ohmmeter indicates a high resistance reading.
  2. Measure resistance between lead 31 and ground with sender removed from coolant for at least 5-15 seconds; ohmmeter indicates a low resistance reading.
Battery Equalizer Troubleshooting diagnostic

⚠ To prevent reverse polarity damage to the battery equalizer, remove the ground (GND) connection first and attach the ground connection last when disconnecting the battery equalizer.

Tools: 12-volt test light with alligator clips, Voltmeter with 0.01 volt resolution, Battery load tester

  1. Remove the ground (GND) connections from the battery equalizer; do not allow contact with other connections.
  2. Verify a differential of 12 volts between the +12 volt and +24 volt terminals using a 12-volt test light; the light will illuminate on a functional unit. Remove the test light.
  3. Connect the test light between the +12 volt and GND terminals; the light will illuminate on a functional unit.
  4. With the test light connected, measure and record the voltage between the +12 volt and +24 volt terminals.
  5. With the test light connected, measure and record the voltage between the +12 volt and GND terminals.
  6. Remove the test light.
  7. Compare the values from steps 4 and 5; the difference should be - 0.5 and +0.13 volts on a functional unit.
Oil Pressure Sender Testing diagnostic

Tools: Ohmmeter, Mechanical oil pressure gauge

  1. Disconnect the oil pressure sender lead 7C.
  2. Check the sender resistance with an ohmmeter.
  3. Compare resistance values when the generator set is shut down and when running at operating temperature to Section 1, Specifications.
  4. Use a mechanical oil pressure gauge to further verify correct readings.
Overcrank Test (Typical) diagnostic
  1. On gas-fueled sets, disconnect the coil wire at the distributor cap and ground it or disconnect the ignition system.
  2. On diesel-fueled sets, unplug the fuel injector harness from ECM or disconnect wire no. 70 from the injector pump solenoid.
  3. Place unit in RUN mode; observe 15-second on-off cranking cycles and maximum 75-second elapsed time to overcrank shutdown.
  4. Observe controller fault lamp and display for an overcrank shutdown.
  5. Place unit in OFF/RESET mode.
  6. Reconnect the ignition coil wire/ignition system, or reconnect the fuel injector harness/wire no. 70.
Speed Sensor Test with Generator Set Running diagnostic

⚠ Keep leads connected to the speed sensor terminals during the test; do not disconnect the leads.

Tools: DC voltmeter

  1. Connect a DC voltmeter between positive (+) lead (wire 24) at the speed sensor and ground (wire 2) with master switch OFF/RESET; read approximately 8- 12 volts DC.
  2. Place master switch in RUN to start the generator set.
  3. Connect DC voltmeter negative probe to 0 terminal (wire 16 white) and positive probe to positive (+) terminal (wire 24 red); read approximately 7- 12 volts DC.
  4. Place master switch in OFF/RESET to stop the generator set.
  5. If sensor emits a signal, check continuity of speed sensor leads (wires 2, 16, 24) between controller P1 connector and sensor terminals.

Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.

Common questions

What is the displacement of the Kohler 1.9L?

The Kohler 1.9L has a displacement of 1.9 liters.

Which generators use the Kohler 1.9L engine?

The Kohler 1.9L powers 3 generator set(s), including Kohler 175REOZT4, Kohler 35 REOZT4, Kohler 45 REOZT4.

What is a common problem with the Kohler 1.9L engine?

A commonly reported issue on generators using the Kohler 1.9L is: Emergency Stop. Fix: Reset the emergency stop switch..