Kohler · REOZ Series (Diesel Commercial Standby)

Kohler 30REOZK4

30 kW standby / 28 kW prime · Diesel · Liquid-cooled

30 kW Tier 4 Final diesel commercial standby generator. Kohler-powered diesel with EPA Tier 4 Final emissions compliance for commercial and institutional applications.

Kohler Kohler 30REOZK4 generator — specifications and details
Standby power
30 kW / 28 kW prime
Voltage options
120/208V, 277/480V, 120/240V
Frequency / Phase
60 Hz · 1/3-phase
Engine
Kohler KDI 1903 TCR · 1.9L
EPA / Emissions
Tier 4 Final
CommercialHealthcareGovernment
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Overview#

The Kohler 30REOZK4 is a 30-kilowatt EPA Tier 4 Final diesel commercial standby generator powered by a Kohler diesel engine at 1800 RPM. Unlike the standard 30REOZK, this model is certified for both stationary emergency and non-emergency applications, making it suitable for jurisdictions with stricter air quality requirements. The unit features a 4-pole rotating-field alternator with PowerBoost excitation and sustained short-circuit capability up to 300% of rated current.

Our service experience#

OnPoint services Tier 4 Final diesel generators across Northern California, where Bay Area Air Quality Management District rules often require Tier 4 certification. The 30REOZK4 adds exhaust aftertreatment components that require periodic inspection as part of the annual PM program.

Engineering specifications

Physical

Length
86 in
Width
40 in
Height
63.9 in
Wet weight
3,080 lb

Acoustic

Sound @ 7m, full load
67 dBA
Enclosure
Sound-attenuated

Fuel system & runtime

Integral fuel tank
77 gal
Fuel use @ full load
2.8 GPH
Fuel use @ 75% load
2.1 GPH
Fuel use @ 50% load
1.4 GPH

Photos

Kohler 30REOZK4 — product photo

Documents & downloads

Spec sheets & manuals

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Configure your Kohler 30REOZK4

Lock the enclosure, fuel system, transfer switch, and add-ons — we'll confirm pricing, availability, and lead time within one business day. Prefer a free-form quote? That option is still here.

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Estimate runtime for the Kohler 30REOZK4

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

35.6 hours(1.5 days)

Fuel consumption ≈ 2.16 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 30REOZK4 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.

ComponentSymptomTypical hoursSeverity
DPF (Diesel Particulate Filter)Regen warning, back-pressure fault, power derate4,380+moderate
Fuel quality / degradationInjector fouling, hard starting, reduced power output4,380+moderate
Battery (starting)Slow crank, failed exercise, low voltage alarm8,760+minor

Frequently Asked Questions

What makes the 30REOZK4 different from the 30REOZK?
The 30REOZK4 is the EPA Tier 4 Final variant, certified for both stationary emergency and non-emergency applications. It uses exhaust aftertreatment to meet stricter emissions requirements.
What engine is in the Kohler 30REOZK4?
The 30REOZK4 uses a Kohler diesel engine rated at 1800 RPM with EPA Tier 4 Final emissions certification.

Compatible equipment

Transfer switches

More in the REOZ Series (Diesel Commercial Standby)

Kohler's diesel commercial standby series — 10 to 510 kW, John Deere and Kohler engines, built for life-safety loads.

View all 33models in this series →

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