40 kW Tier 4 Final diesel commercial standby generator. Kohler-powered diesel with EPA Tier 4 Final emissions compliance for commercial and institutional applications.
The Kohler 40REOZK4 is a 40-kilowatt EPA Tier 4 Final diesel commercial standby generator powered by a Kohler diesel engine at 1800 RPM. It achieves Tier 4 Final compliance through cooled exhaust gas recirculation (EGR) and a diesel oxidation catalyst (DOC). The unit is certified for both stationary emergency and non-emergency applications and features a sound-attenuating housing rated at 67 dB(A) at 7 meters, integrated environmental containment, and an electronic isochronous governor.
OnPoint services Tier 4 Final diesel generators across Northern California, where Bay Area air quality rules frequently require Tier 4 certification. The 40REOZK4 adds cooled EGR and DOC components that require periodic inspection during annual maintenance.
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Adjust load percent and tank size to estimate runtime. Pre-filled with this model's spec where available.
Estimate runtime on this tank
Estimated runtime
30.2 hours(1.3 days)
Fuel consumption ≈ 2.55 GPH at 75% load. Estimate based on industry-typical 1800 RPM standby curves (≈0.07 GPH/kW at full load). Actual consumption varies by engine, ambient temperature, fuel quality, and tuning.
Service intervals
Manufacturer-recommended intervals for the Kohler 40REOZK4 under standby duty. Field intervals may differ based on load profile, ambient conditions, and fuel quality.
Oil & filter
Every 250 hours or 12 months
Coolant change
Every 2000 hours
Air filter
Every 500 hours
Fuel filter
Every 250 hours
Major overhaul
≈ 8,000 hours
Load bank test
Every 12 months
Common failure modes
What we've seen fail on this platform. Use as a service-planning reference, not a diagnostic — actual failure modes depend heavily on duty cycle and maintenance history.
Component
Symptom
Typical hours
Severity
DPF (Diesel Particulate Filter)
Regen warning, back-pressure fault, power derate
4,380+
moderate
Fuel quality / degradation
Injector fouling, hard starting, reduced power output
4,380+
moderate
Battery (starting)
Slow crank, failed exercise, low voltage alarm
8,760+
minor
Frequently Asked Questions
What makes the 40REOZK4 different from the 40REOZK?
The 40REOZK4 is the EPA Tier 4 Final variant with cooled EGR and diesel oxidation catalyst for stricter emissions compliance. It is certified for both stationary emergency and non-emergency applications.
What is the sound level of the 40REOZK4?
Per Kohler specifications, the 40REOZK4 is rated at 67 dB(A) at 7 meters at full load with the sound-attenuating housing.
Does the 40REOZK4 include fuel containment?
Yes. The unit includes a 125% environmental containment basin for oil/coolant and a 110% secondary fuel containment tank with UL 142 listed subbase fuel tank for 24-hour minimum runtime at prime rating.
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