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Caterpillar 3304B Engine

The Caterpillar 3304B is a 7 L 4-cylinder naturally aspirated engine rated at 1800 rpm, producing up to 73 kW. It powers generator sets from Caterpillar, including the 3304. It holds 22 L (5.8 gal) of oil and 32 L (8.5 gal) of coolant.

Also known as: Caterpillar 3304B

Part of the Caterpillar 3304B engine family — 2 variants share parts & fitment.

7.0 L
Displacement
4
Cylinders
1800 rpm
Rated speed
73 kW
Gross power

Engine specifications

Oil capacity22.0 L
Coolant capacity32.0 L
Displacement7.0 L
Cylinders4
AspirationNaturally Aspirated
Rated speed1800 rpm
Gross power73 kW

Maintenance schedule

ItemSpecCapacityPart #Interval
Coolant32.0 L—
OilCaterpillar DEO 10W30 or 15W4022.0 L—500 hr

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

Service specifications

21
TypeItemValueUnitCondition
ClearanceCrankshaft end play.178 to .635mm (0.0070 to 0.0250 inch)measured with dial indicator
ClearanceCrankshaft end play after assembly0.178 to 0.635mm (0.0070 to 0.0250 inch)after assembly
ClearanceEnd play at heat sink after assembly0.076 to 0.635mm (0.0030 to 0.0250 inch)after assembly
ClearanceGap at 3, 6, 9, 12 o'clock positions0.03 to 0.13mm (0.001 to 0.005 inch)between
ClearanceGap between generator and flywheel housing at locations (E), (F), (G), (H)>0.03 and <0.13mm (0.001 inch to 0.005 inch)more than 0.03 mm and less than 0.13 mm
ClearanceGenerator forward offset from midpoint of end play+ 0.50mm (+ 0.0200 inch)while generator supported by crane
ClearanceRotor end play3.81 to 7.62mm (.150 to .300 inch)approximately
ClearanceShim thickness divisor for number of shims0.8mm (0.03 inch)divide Letter L by this value
ClearanceSupport deflection during bolt tightening0.13mm (0.005 inch)maximum allowed movement
TorqueBearing Nut Torque (129-3253 Spanner Socket, 121-9871 Bearing Nut)2375N·m
TorqueBearing Nut Torque (129-3254 Spanner Socket, 119-3711 Bearing Nut)2375N·m
TorqueBolts (10)100N-m (75 lb ft)Tighten in pairs at 180 degree intervals in three stages
TorqueBolts (7) for shim pack and plate assembly525 + 45N-m (390 + 30 lb ft)Tighten bolts (7)
TorqueCoupling plate assembly bolts (5)525 + 25N-m (390 + 20 lb ft)Tighten in 180 degree intervals in three stages
TorqueFan mounting bolts (11)200N-m (150 Ib ft)Tighten in pairs at 180 degree intervals in three stages
TorqueGenerator mounting bolts (half of standard torque)450N-m (332 lb ft)one half of standard torque
TorqueGenerator support bolts (half of final torque)450N-m (332 Ib ft)half of final torque
TorqueLocknut torque (260-0626 Spanner Socket Assembly, 1T-0229 High Torque Locknut)985N·m
TorqueSolenoid nut torque (FT3198 Solenoid Tool, 352-2733 solenoid)3.75Nm+/- .75
TorqueTightening torque for 369-5916 Lifting Eyebolt (M12 Hex Bit)115N·m
TorqueWorking torque capacity of locknut spanner wrenches (126-6608 / 126-6609)950N·m

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

Recommended fluids

FluidGradeStandardAmbientCapacityNotes
CoolantCat DEACDiesel; 3,000 Service Hours or Three Years; annual S·O·SSM Level 2 coolant sampling and analysis
CoolantCat ELCDiesel; 12,000 Service Hours or Six Years; add Cat ELC Extender at 6,000 service hours or one half of service life; annual S·O·SSM Level 2 coolant sampling and analysis
CoolantCat NGECNatural Gas; 16,000 Service Hours or Three Years; use interval that occurs first
Engine oilCat NGEONatural Gas
Engine oilCat Arctic DEO SYN SAE 0W-30-40°C to 30°CEngine Crankcase; Industrial Engines
Engine oilCat DEO SYN SAE 5W-40-30°C to 50°CEngine Crankcase; Industrial Engines
Engine oilCat DEO SAE 10W-30-18°C to 40°CEngine Crankcase; Industrial Engines
Engine oilCat DEO SAE 15W-40-9°C to 50°CEngine Crankcase; Industrial Engines
GreaseCat Generator Set GreasePart Number 108-8611

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

Procedures

8
Alignment Of Electric Sets With Supports At The Flywheel Housing / Installation Of A New Generator Or Flexible Plates adjustment

Tools: crane, dial indicator, shims, torque wrench

  1. Loosen all bolts connecting base to foundation; loosen all bolts fastening engine supports and generator supports to base.
  2. Ensure enough clearance between bolts and bolt holes in base, engine supports, generator supports at all locations.
  3. Check clearance between base and foundation at all mounting locations; use shims to prevent deflection; tighten base-to-foundation bolts to final torque.
  4. While generator supported by crane, loosen all bolts (2) fastening generator to flywheel housing; tighten alternate bolts to final torque; check clearance between base and engine and generator support
  5. Tighten all bolts fastening engine supports and generator supports to base to half of final torque; loosen all bolts (2); measure gap between generator and flywheel housing; ensure bolts centered in c
  6. Gaps at (E), (F), (G), (H) should be more than 0.03 mm (0.001 inch) and less than 0.13 mm (0.005 inch); adjust shims or move rear of generator right or left.
  7. After shim correction, tighten generator support bolts to half of final torque 450 N-m (332 Ib ft); check gaps; repeat until 0.13 mm (0.005 inch) or less; begin with Step 5.
  8. Install dial indicator on base with tip next to support mounting bolt (4); put tip on support (3); check while tightening bolt to final torque; if indicator moves more than 0.13 mm (0.005 inch), insta
Alignment Of Electric Sets Without Supports At The Flywheel Housing adjustment

Tools: shims, torque wrench

  1. Loosen all bolts connecting base to foundation; loosen all bolts fastening generator supports and engine supports to base.
  2. Ensure clearance between bolts and bolt holes in base, engine supports, generator supports at all locations.
  3. Check clearance between base and foundation at all mounting locations; use shims to prevent base deflection; tighten base-to-foundation bolts to final torque.
  4. Check clearance between base and engine, base and engine supports, base and generator supports over entire length; use shims to prevent support deflection; tighten all mounting bolts to final torque.
Rechecking The Alignment adjustment

Tools: torque wrench, shims

  1. Loosen the sixteen close coupled adapter bolts (2); visually ensure they are centered in clearance holes.
  2. Check gaps at 3, 6, 9, and 12 o'clock positions; use 2, 4, 8, and 10 o'clock if 12 and 6 are inaccessible.
  3. If gaps are between 0.03 mm (0.001 inch) and 0.13 mm (0.005 inch), tighten all bolts; alignment check complete. If not, loosen bolts fastening generator to base frame; adjust shims; move rear of gener
  4. After adjustment, tighten generator mounting bolts to one half of standard torque 450 N-m (332 lb ft); repeat procedure starting with Step 1.
Installation Of The Generator For Generator Sets That Are Equipped With A 3500 Engine installation

⚠ Damage to engine and generator can result if electric set is operated with a plate assembly that does not have proper clearance.

⚠ If N or O is less than initial A, disassemble and check coupling plate for bowing; replace if bowed.

Tools: dial indicator, straight edge, magnetic bases, crane, torque wrench, 17 5N-4478 Plates

  1. Ensure generator is disengaged from engine; clean generator support and base contact surfaces; remove protective material from flywheel pilot bearing bore and coupling contact surface.
  2. Remove two engine side covers; rotate engine until no. 1 crankshaft throw is perpendicular; measure crankshaft end play with dial indicator; record as A and divide by two for B.
  3. With crankshaft at extreme forward position, measure distance from straight edge to flywheel housing mounting surface (C) and flywheel pilot surface (D); subtract D from C for E.
  4. Remove coupling bolts and washers; remove plates, shims, and exhaust fan; lift rotor; locate rotor so air gap equal; move rotor to extreme rear.
  5. Place dial indicator on vertical surface of heat sink at rear of rotor shaft; measure rotor end play (approximately 3.81 to 7.62 mm); record F and divide by two for G.
  6. Move rotor to extreme rear; position straight edge across mounting ring diameter; measure distance to mounting ring surface (H) and hub mounting surface (I); subtract H from I for J.
  7. Bolt a standard set of 17 5N-4478 Plates together; measure thickness in two locations along contour; average as K.
  8. Determine number of shims: subtract B, E, G, K from J for L; divide L by 0.8 mm (0.03 inch) for M; round up.
  9. Put coupling plate in flywheel bore; check clearance between coupling plate outside diameter and flywheel bore inside diameter.
  10. Install coupling plate assembly, bolts (6) and calculated shims; tighten bolts (5) in 180 degree intervals in three stages to 525 + 25 N-m (390 + 20 lb ft).
  11. Install guide bolts in flywheel; put generator on engine; install bolts (10); tighten to 100 N-m (75 lb ft) in pairs at 180 degree intervals in three stages.
  12. While crane supports generator, place dial indicator on heat sink vertical surface; push generator forward within + 0.50 mm (+ 0.0200 inch) of midpoint of end play.
  13. Install fan mounting bolts (11) into flywheel; tighten to 200 N-m (150 Ib ft) in pairs at 180 degree intervals in three stages.
  14. Place dial indicators on no. 1 crankshaft throw and heat sink; push crankshaft forward; check crankshaft end play 0.178 to 0.635 mm and heat sink end play 0.076 to 0.635 mm; record N and O.
  15. If N or O is less than initial A, disassemble; check coupling plate for bowing; replace if bowed; check calculations; install generator and repeat steps 13 and 15.
Installation Of The Generator For Generator Sets That Are Not Equipped With A 3500 Engine installation

⚠ Damage to engine and generator can result if electric set is operated with a plate assembly that does not have proper clearance.

Tools: dial indicator, indicator assembly, bar, torque wrench, guide bolt, crane

  1. Remove dirt, burrs, paint from generator support and base contact surfaces; remove protective material from flywheel pilot bearing bore and coupling contact surface.
  2. Remove timing pointer cover; install indicator assembly on front of engine; tip contacts crankshaft pulley face.
  3. Position plate assembly in flywheel bore; check clearance between plate outside diameter and bore inside diameter.
  4. Install full shim pack and plate assembly on generator with bolts; tighten bolts to 525 + 45 N-m (390 + 30 lb ft).
  5. Install guide bolt in flywheel; put generator on engine; install bolts (9) and (10); tighten but do not bend locks under bolts (8).
  6. Use dial indicator to check crankshaft end play; if reading differs from initial, remove generator and enough shims to get original end play.
  7. Install generator again and check crankshaft end play; after correct shims, bend locks under bolts (8).
Installation of two-piece seal into slack adjuster piston (209-6381 Seal Installer Group) maintenance

Tools: 207-3440 Loading Mandrel, 207-3442 Ring Pusher, 207-3444 Seal Sizer, 8F-8178 Bolt

  1. Place 207-3440 Loading Mandrel over small piston.
  2. Place inner portion of two-piece seal onto mandrel and push onto piston using 207-3442 Ring Pusher. Repeat for outer portion of seal.
  3. With both sets of seals installed, push piston assembly into 207-3444 Seal Sizer.
  4. Allow seals to compress for one minute and then install small piston into large piston.
Sprocket wheel removal - 8T-5243 Adapter Group installation maintenance

Tools: 8T-5243 Adapter Group, 7B-2499 Ring, 6H-4158 Pin, 5F-9306 Arm, 8S-9975 Ram Adapter, 9S-8900 Cylinder Group

  1. Install adapter groups evenly spaced in the holes in the sprocket flange; install the hooked adapter (1) first, then the plate (2).
  2. Fasten plate to adapter with two bolts (3) and washers (4); plate retains adapter in sprocket wheel.
  3. Before installing remainder of tooling, loosen bolt (5) to leave about 6.35 mm (0.25 in) gap between retainer (6) and sprocket wheel.
  4. Install the hydraulic cylinder and the remainder of the tooling in the conventional manner.
STOR Plug Assembly application for disc brake piston retainer spring (174-5354) repair

Tools: 174-5354 STOR Plug Assembly, 134-2562 Guides, 9S-9334 Plugs, 6N-9155 Pin

  1. Insert four 134-2562 Guides and discontinued 130-8718 Springs as an assembly into brake group anchor exterior holes where 9S-9334 Plugs are normally located.
  2. Insert four 174-5354 Plug Assemblies into exterior holes and finger tighten.
  3. Screw in attached bolts until guide noses protrude through brake piston.
  4. Insert discontinued 6N-9155 Pin into each guide hole and remove bolts and plugs.
  5. Insert four 9S-9334 Plugs into vacated holes.

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

Parts cataloged across the Caterpillar 3304B family

32
Part #DescriptionCategory
1M7250Air filter housingAir filter
7M4705V-beltBelt
M-1W3711Alternator, V, .69in (17.5mm) - 67.99in (1727mm)Belt
1R-1740Standard Efficiency Fuel FilterFilter
151-2409Filter water separatorFuel filter
1R0750Filter fuelFuel filter
3S3875Filter fuelFuel filter
8N0205Filter water separatorFuel filter
8N9803Filter water separatorFuel filter
9N3717Filter water separatorFuel filter
9Y1979Gasket exhaust manifoldGasket
3T9561Glow plugGlow plug
3T9562Glow plugGlow plug
1R0741Filter hydraulicHydraulic filter
9T0973Filter hydraulic/transmissionHydraulic filter
7N5910Water pump impellerImpeller
102-2828Filter oilOil filter
1R0719Filter oilOil filter
9M9740Filter oilOil filter
8N1721Connecting rodService part / kit
8N1984Connecting rodService part / kit
PEHP3036Cat Reman Short and Long BlocksService part / kit
PEHP3036-01Cat Reman Short and Long BlocksService part / kit
172-7766Water pumpPump
1W1695Lift/transfer pumpPump
6I1346Oil pumpPump
4W3864Water pump sealSeal
DM-6J6915SEAL RING 3304Seal
3E2026SwitchSensor
ESD5500ESpeed ControllerSpeed controller
111-8010ThermostatThermostat
4N8969TurbochargerTurbocharger

Parts cataloged across all variants of this engine family — verify the exact part fits your specific variant and serial number before ordering.

Aftermarket parts that fit this engine

55
12Teeth FridayParts $419.99 207-1560 FridayParts $422.25 7G-7889 FridayParts $187.20 SinoCMP $329.00 2W-1709 FridayParts $93.98 124-5572 KuduParts $50.00 FridayParts $52.10 6I-2499 KuduParts $63.00 FridayParts $65.00 6I-2500 FridayParts $87.99 7T-2798 FridayParts $41.23 140-2246 FridayParts $162.56 391-8229 FridayParts $162.56 8N-1984 Amazon eBay $275.00 FridayParts $114.19 2PCS FridayParts $7.59 SinoCMP $27.00 KuduParts $38.00 2P2696 FridayParts $65.00 4N-7694 FridayParts $1228.00 4N-7695 FridayParts $1228.00 1W9812 KuduParts $84.00 FridayParts $85.99 142-5867 eBay $41.66 FridayParts $39.38 1N-3574 FridayParts $2373.63 1B-7709 FridayParts $19.99 4P-8915 FridayParts $98.89 7W-8003 FridayParts $1248.80 133-6350 FridayParts $1301.00 1R-0749 Amazon Amazon eBay $135.88 eBay $135.88 NAPA $28.51 NAPA $28.51 KuduParts $17.00 FridayParts $47.50 3R-2251 FridayParts $39.99 9G-8010 eBay $39.00 FridayParts $16.90 170-0061 FridayParts $29.99 KuduParts $39.00 133-5673 Amazon eBay $19.99 eBay $19.99 NAPA $70.35 KuduParts $19.00 FridayParts $20.99 513-4490 Amazon eBay $23.43 PartsGeek $48.97 FridayParts $29.99 KuduParts $39.00 2W-4234 FridayParts $68.83 3I-1169 FridayParts $68.83 129-0375 KuduParts $22.00 FridayParts $24.26 1W-0613 KuduParts $38.00 FridayParts $40.00 5N-8757 FridayParts $359.99 5R-3178 FridayParts $23.25 163-8516 FridayParts $57.79 6N-1030 FridayParts $545.30 2W-1711 FridayParts $379.00 168-4531 FridayParts $113.50 613-5133 FridayParts $2440.86 6I-1872 FridayParts $2440.86 036-1865 FridayParts $35.11 6L-8617 FridayParts $39.59 3L-2866 FridayParts $39.59 9M-0853 FridayParts $201.39 561-2205 FridayParts $852.80 2N-8378 FridayParts $852.80 4N-6657 FridayParts $852.80 148-8861 FridayParts $248.36 102-0050 Amazon eBay FridayParts $72.00 4W-8471 FridayParts $197.56 8T-1606 FridayParts $85.80 172-7767 FridayParts $236.99 CA1W9812 KuduParts $84.00 CA3801513 KuduParts $84.00 3801513 KuduParts $84.00

Parts listed by aftermarket suppliers as fitting this engine — leads compiled from supplier catalogs; verify the exact part for your serial number.

Also used in

12
  • Broyt X20 — Excavator
  • Broyt X21 — Excavator
  • Broyt X21TL — Excavator
  • Caterpillar 225 — Excavator Tracked
  • Caterpillar 527 — Skidder
  • Caterpillar 963 — Loader Tracked
  • Caterpillar CP643 — Compactor
  • Caterpillar CP653 — Compactor
  • Caterpillar D4E — Tractor Tracked
  • Caterpillar D5H — Tractor Tracked
  • Caterpillar D5H II — Tractor Tracked
  • Caterpillar D5H LGP — Tractor Tracked

Other equipment known to use this engine, via filter-application cross-reference — useful for sourcing parts even when your exact machine isn't listed elsewhere on this page.

Common questions

What is the oil capacity of the Caterpillar 3304B?

The Caterpillar 3304B engine has an oil capacity of 22.0 liters.

What is the displacement of the Caterpillar 3304B?

The Caterpillar 3304B has a displacement of 7.0 liters with 4 cylinders.

Which generators use the Caterpillar 3304B engine?

The Caterpillar 3304B powers 1 generator set(s), including Caterpillar 3304.

How often should you change the oil in the Caterpillar 3304B?

The Caterpillar 3304B oil change interval is every 500 hours.