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Generac MDG20IF4-MLG20IF4 Generator Set

The Generac MDG20IF4-MLG20IF4 is a 20 kW (20 kVA) standby generator set powered by a Isuzu 4LE2TAGV-03 engine. It is available at 120 V and 240 V. It holds about 10.4 L (2.7 gal) of oil and 17 L (4.5 gal) of coolant. The same 4LE2TAGV-03 engine also powers generator sets from Isuzu, John Deere and Magnum.

20 kW
Standby
2.18 L
Displacement
10.4 L
Oil capacity
1
Document types

How to read your Generac serial & model number →

Service parts for the MDG20IF4-MLG20IF4

Grouped by system, with how many of each the parts manual calls for.

Fuel system

1 required

Oil system

1 required

Prices captured from merchant listings; some links are affiliate links. Confirm against your serial number before ordering.

Specifications

Standby power20 kW
Standby kVA20
Prime power19 kW
Oil capacity10.4 L
AlternatorMarathon 334CSA3028
Voltage options120 V, 240 V

Engine

Isuzu 4LE2TAGV-03
Oil capacity10.4 L
Coolant capacity17.0 L
Displacement2.18 L
AspirationLiquid cooled
Rated speed1800 rpm

Maintenance & consumables

for the Isuzu 4LE2TAGV-03
ItemSpecCapacityPart #Interval
Air filterDry type cartridge air filter250 hr
Fuel filterFuel filter with replaceable element69858500 hr Amazon $21.83 eBay $21.83 FridayParts $36.28
Oil filter6705703041000 hr Amazon eBay $16.89 PartsGeek $7.98 FridayParts $20.19
BatteryClean Battery1000 hr
BeltCheck Fan Belt Tension (Replace If Necessary)1000 hr
CoolantCheck Coolant Level250 hr
OilCheck Oil Level250 hr
Spark plugReplace Air Filter Element1000 hr

Compatible filters for the Isuzu 4LE2TAGV-03 — cross-referenced via Donaldson. Options to verify against your serial number, not confirmed for this exact unit.

  • Air filter: Generac OE3557 Generac OE3656 Isuzu 8972319000 Isuzu 5864014350 Isuzu 8972599390

Common questions

What size generator is the Generac MDG20IF4-MLG20IF4?

The Generac MDG20IF4-MLG20IF4 is rated 20 kW standby (20.0 kVA).

What engine is in the Generac MDG20IF4-MLG20IF4?

The Generac MDG20IF4-MLG20IF4 is powered by the Isuzu 4LE2TAGV-03 engine.

What is the oil capacity of the Generac MDG20IF4-MLG20IF4?

The Isuzu 4LE2TAGV-03 engine in the Generac MDG20IF4-MLG20IF4 has an oil capacity of 10.4 liters.

What alternator does the Generac MDG20IF4-MLG20IF4 use?

The Generac MDG20IF4-MLG20IF4 uses a Marathon 334CSA3028 alternator.

What oil filter does the Generac MDG20IF4-MLG20IF4 use?

The Generac MDG20IF4-MLG20IF4 uses oil filter part number 670570304.

What fuel filter does the Generac MDG20IF4-MLG20IF4 use?

The Generac MDG20IF4-MLG20IF4 uses fuel filter part number 69858.

What air filter fits the Generac MDG20IF4-MLG20IF4?

The Generac MDG20IF4-MLG20IF4 uses air filter part numbers GENERAC OE3557, GENERAC OE3656.

Troubleshooting

2

Symptoms & remedies

SymptomCauseRemedy
Low Oil Pressure Shut-downLow oil level, Oil leaking from engine, Oil pressure senderCheck oil level on dipstick. Add oil, if needed. Visually inspect the engine for leaks. Restart unit and verify loss of pressure. Shut down immediately if pressure does not reach 5 psi (34 kPa) within five seconds. Refer to engine operator’s manual to identify corrective action.
High Coolant Temperature ShutdownLow coolant level, Blockage in radiator, Leakage in coolant hoses, engine block, or water pumpAdd coolant if needed. Allow engine to cool, then check coolant level in radiator. Restart engine and check coolant temperature (on controller). Stop engine immediately if coolant temperature is 210°F (99°C) or more. Check radiator shroud and ducting for blockage and remove any foreign matter. Inspect for visible leaks. Check tension of water pump serpentine drive belt. Remove load on generator and restart engine. Check coolant temperature and shut engine down immediately if it starts to overheat. Refer to the engine operator’s manual for additional information on engine overheating.

Fault codes and symptom→remedy steps extracted from this model’s service/owner documentation; verify against the official manual before servicing.

Parts

4
Part #DescriptionQtySystem
01035Central Lift PointCentral lift point Amazon eBay
01144ControllerController Amazon eBay
90243Air Filter ElementAir filter Amazon eBay
209649Form: SFC626B1Service part / kit Amazon eBay

Service, wear & replacement parts referenced for this model and its engine — confirm the exact part for your serial number. See the full parts catalog to search and cross-reference.

Fuel consumption

RatingLoadL/hgal/h
Prime100%7.82.1

Available documents

Operator's manual — 37100 (Generac)
Full service, cheapest listings

Priced items from this model's own parts manual.

Fuel filter 69858$21.83
Oil filter 670570304$7.98
2 priced items$29.81