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Caterpillar CM25-8 Engine

The Caterpillar CM25-8 is a 163 L engine. It powers generator sets from Caterpillar, including the CM25.

Also known as: Caterpillar CM25-8

Part of the Caterpillar CM25 engine family — 3 variants share parts & fitment.

163.0 L
Displacement

Engine specifications

Displacement163.0 L

Generator sets powered by this engine

1
Caterpillar CM25

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Service intervals

8
ItemActionHoursMonthsNotes
Engine oil (S-O-S oil sample)Test125 hrSevere service occurs at high loads, in high temperatures, and in dusty conditions
Coolant (S-O-S coolant analysis Level 1)Test250 hrCat ELC - Every 250 Hours; also the recommended sampling interval for all conventional heavy-duty coolant/antifreeze and for commercial coolants that meet Cat EC-1
Engine crankcase oil (S-O-S oil sample)Test250 hrTable 6 S-O-S Oil Sampling Interval; severe applications may require a more frequent oil sampling interval
SCA (Supplemental Coolant Additive) concentrationTest250 hrTest the concentration of SCA or submit a coolant sample at 250 hour intervals or at PM Level 1 intervals; check at every oil change or every 250 hours, whichever occurs first
Coolant (S-O-S coolant analysis Level 2)Test500 hr12 moFirst service — For new systems, refilled systems, and converted systems that use Cat ELC or Cat DEAC; also every year; use the interval that occurs first
Cat ELC Extender addition (cooling system)Other6000 hrTreat the cooling system with Cat ELC Extender at 6000 hours or one half of the coolant service life
Coolant (Cat ELC)Change12000 hr12000 service hours or six years; use the interval that occurs first
Coolant (S-O-S coolant analysis Level 1 and Level 2)Test12 moCat DEAC - Yearly

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

12
TypeItemValueUnitCondition
OtherGross Input Torque (TH55-E70)12 667N•m (9350 lb-ft)
OtherGross Input Torque (TH55-E90)12 677N•m (9350 lb-ft)
OtherRating condition (diesel 7 L and higher)99 kPa (29.31 in Hg) dry barometer, 25°C (77°F)SAE J1995 inlet air standard
OtherRating condition (diesel up to 6.6 L)100 kPa (29.5 in Hg) total barometric pressure, 1 kPa (.295 in Hg) vapor pressure, 25°C (77°F)ISO/TR14396 inlet air standard
OtherRating condition (gas)100 kPa (29.61 in Hg) and 25°C (77°F)SAE J1349 standard
OtherStall Torque Ratio (TH55-E70)2.23
OtherStall Torque Ratio (TH55-E90)2.23
PressureWS255 pump plunger load238,000lb (107,960 kg)
PressureWS273XD pump plunger load275,000lb (124 738 kg)
PressureWS305XD pump plunger load250,000lb (113 398 kg)
SpeedMaximum Input Speed (TH55-E70/TH55-E90 transmissions)1970rpm
SpeedRated Input Speed (TH55-E70/TH55-E90 transmissions)1900rpm

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 DEAC (Diesel Engine Antifreeze/Coolant)Acceptable coolant; commercial heavy-duty antifreeze/coolant must meet ASTM D4985 or ASTM D6210Conventional heavy-duty coolant/antifreeze. Caterpillar recommends a 1:1 mixture of water and glycol. Do not use a commercial coolant/antifreeze that only meets the ASTM D3306 specification. Do not use Cat SCA at the initial fill when Cat DEAC is used.
CoolantCat ELC (Extended Life Coolant)Caterpillar EC-1 specification (preferred); also meets ASTM D4985, ASTM D6210, and ASTM D3306Service life of 12000 service hours or six years. Premixed ELC provides freeze protection to -37 C (-34 F); ELC Concentrate can be used to lower the freezing point to -52 C (-62 F). An Extender is the only additional maintenance needed at 6000 service hours or one half of the ELC service life. Cat ELC cooling systems can withstand contamination to a maximum of ten percent of conventional heavy-duty coolant/antifreeze and/or SCA.
CoolantCat SCA (Supplemental Coolant Additive) with waterSCA concentration in a cooling system that uses SCA and water should be six to eight percent by volume; do not exceed the eight percent maximum concentration. If Cat SCA is not used, the commercial SCA must provide a minimum of 2400 mg/L or 2400 ppm (140 grains/US gal) of nitrites in the final coolant mixture when used with water, and a minimum of 1400 mg/L or 1400 ppm (82 grains/US gal) with heavy-duty coolant/antifreeze.
CoolantGlycol (ethylene glycol / propylene glycol)Propylene glycol coolant must meet ASTM D6210-04Ethylene glycol: 50 percent = freeze protection -37 C (-34 F), boil protection 106 C (223 F); 60 percent = -52 C (-62 F), 111 C (232 F). Propylene glycol: 50 percent = -32 C (-26 F), 106 C (223 F). Do not use propylene glycol in concentrations that exceed 50 percent; do not use ethylene glycol in concentrations that exceed 60 percent. All Caterpillar diesel engines equipped with air-to-air aftercooling (ATAAC) require a minimum of 30 percent glycol.
Engine oilCat DEO (Diesel Engine Oil) 10W-30 and 15W-40Cat ECF-1 (exceeds); API CI-4, API CI-4 PLUS, API CH-4, API CG-4, API CF (Cat DEO SAE 15W-40)Caterpillar oils are used to fill diesel engines at the factory. Non-Caterpillar commercial oils are second choice oils. Do not use API CF-4 oils in Caterpillar diesel engines. Do not use single grade API CF oils or multigrade API CF oils in 3500 Series, C175 Series and smaller DI diesel engines.
Engine oilCommercial oils (DI engines)Cat ECF-1 required; API CG-4 multigrade acceptable; API CH-4, API CI-4 and API CI-4 PLUS acceptable only if the requirements of Cat ECF-1 are met; do not use API CF-4 oilsMinimum TBN must be 10 times the fuel sulfur level (ASTM D2896); minimum TBN of the oil is 5 regardless of a low fuel sulfur level. API CG-4 oils: do not exceed the standard oil drain interval.
Engine oilCommercial oils (PC engines)Cat ECF-1; API CH-4, API CI-4, API CI-4 PLUS (if Cat ECF-1 requirements met); API CG-4 multigrade; API CF-4 multigrade; API CFMinimum TBN of the oil that is used in PC engines must be 20 times the fuel sulfur level; minimum TBN of new oil is five. Change the oil when the TBN deteriorates to 50 percent of the original TBN.
Engine oilRe-refined base stock oilsAcceptable if they meet the performance requirements specified by Caterpillar; filtering is inadequate for producing high quality re-refined base stock oils.
Engine oilSynthetic base stock oilsAcceptable if they meet the performance requirements specified for the engine compartment. Caterpillar does not recommend the automatic extension of oil drain intervals for any type of oil.
Engine oilSAE 0W-20-40°C to 10°CTable 1 Lubricant Viscosities for Ambient Temperatures (DI diesel engines)
Engine oilSAE 0W-30-40°C to 30°CTable 1 Lubricant Viscosities for Ambient Temperatures (DI diesel engines)
Engine oilSAE 0W-40-40°C to 40°CTable 1 Lubricant Viscosities for Ambient Temperatures (DI diesel engines)
Engine oilSAE 5W-30-30°C to 30°CTable 1 Lubricant Viscosities for Ambient Temperatures (DI diesel engines)
Engine oilSAE 5W-40-30°C to 50°CTable 1 Lubricant Viscosities for Ambient Temperatures (DI diesel engines)
Engine oilSAE 10W-30-18°C to 40°CTable 1 Lubricant Viscosities for Ambient Temperatures (DI diesel engines); SAE 10W-30 is the preferred viscosity grade for the 3116, 3126, C7, C-9 and C9 diesel engines between -18 C (0 F) and 40 C (104 F)
Engine oilSAE 10W-40-18°C to 50°CTable 1 Lubricant Viscosities for Ambient Temperatures (DI diesel engines)
Engine oilSAE 15W-40-9°C to 50°CTable 1 Lubricant Viscosities for Ambient Temperatures (DI diesel engines)
Engine oilCat SAEO SAE 30API CF-4 category0°C to 40°CTable 2 - 3116 and 3126 Marine Engines with mechanical unit injection; factory fill has API CF-4 category and viscosity grade of SAE 30
Engine oilSAE 300°C to 40°CTable 3 Lubricant Viscosities for Ambient Temperatures - PC engines only
Engine oilCat SAEO SAE 40API CF-4 category5°C to 50°CTable 2 - 3116 and 3126 Marine Engines with mechanical unit injection. Caterpillar does not recommend the use of multigrade oils in the 3116 and 3126 Marine Diesel Engines that use mechanical unit injection.
Engine oilSAE 405°C to 50°CTable 3 Lubricant Viscosities for Ambient Temperatures - PC engines only
Fuel35° API gravity, LHV 42 780 kJ/kg (18,390 btu/lb)SAE J1995Diesel engines 7 liter and higher; used at 29°C (84.2°F) with density 838.9 g/L
FuelBiodiesel blendsCaterpillar biodiesel specification, ASTM D6751, or EN 14214May be blended in amounts up to a maximum of 30 percent (models C6.6, C7, C9, C11, C13, C15, C18, C27, C32, 3114, 3116, 3126, 3176, 3196, 3208, 3306, C-9, C-10, C-12, 3406, C-15, C-16, C-18, 3456, 3408, 3412, 3500 Series, C175 Series, 3600 Series, C280 Series, CM20, CM25 and CM32); for 3003 through 3034, 3046, 3054, 3056, 3064, and 3066 engines, maximum ratio of 5% biodiesel to 95% acceptable diesel fuel. Caterpillar recommends a maximum of one year for fuel storage.
FuelEPA 2D 89.330-96EPA 2D 89.330-96Diesel engines up to 6.6 liter; density 0.845-0.850 kg/L @ 15°C (59°F); fuel inlet temperature 40°C (104°F)
FuelJP-5, JP-8, Jet A-1MIL-DTL-5624U, MIL-DTL-83133E, ASTM D1655-05Table 8 - may be used in extreme cold ambient conditions down to -54 C (-65 F); these fuels typically do NOT meet ULSD fuel requirements; if viscosity is below 1.4 cSt at 40 C (104 F) use the fuel only in temperatures below 0 C (32 F); do not use any fuels with a viscosity of less than 1.2 cSt at 40 C (104 F).
FuelNo. 1-D / No. 2-D distillate diesel fuelASTM D975; Caterpillar Specification for Distillate Diesel Fuel (Table 7)Cetane number 40 minimum (DI engines) or 35 minimum (PC engines); aromatics 35% maximum; ash 0.02% maximum (weight); carbon residue on 10% bottoms 0.35% maximum (weight); copper strip corrosion No. 3 maximum; distillation 10% at 282 C (540 F) maximum, 90% at 360 C (680 F) maximum; flash point legal limit minimum; pour point 6 C (10 F) minimum below ambient temperature; sulfur 0.1% maximum; kinematic viscosity 1.4 cSt minimum and 20.0 cSt maximum as delivered to the fuel injection pumps; water and sediment 0.1% maximum; water 0.1% maximum; sediment 0.05% maximum; gums and resins 10 mg per 100 mL maximum; lubricity 0.52 mm (0.0205 inch) maximum at 60 C (140 F) by ASTM D6079; cloud point must not exceed the lowest expected ambient temperature.
FuelUltra Low Sulfur Diesel (ULSD)ASTM D5453, ASTM D2622, or DIN 51400; <15 ppm (0.0015%) sulfurIn North America, diesel fuel identified as "ASTM D975 Grade No. 1-D S15" or "ASTM D975 Grade No. 2-D S15" meeting "ASTM D975 Thermal Stability Guideline X2.10.2.2" generally meets the Caterpillar requirements for ULSD fuel.
Fueldry natural gas, LHV 35.54 MJ/Nm3 (905 btu/ft3)Gas ratings based on SAE J1349 standard conditions of 100 kPa (29.61 in Hg) and 25°C (77°F)
Gear oilCat TDTO (Transmission/Drive Train Oil)Caterpillar TO-4 oil specificationTable 4 - SAE 30: -15 C (5 F) to 80 C (176 F); SAE 50: -5 C (23 F) to 95 C (203 F). Formulated for transmissions and drive trains only and should not be used in engines. Cat GO (Gear Oil) is not the same as Cat TDTO and does not meet Caterpillar's specifications for TO-4 oil.
GreaseCat Advanced 3Moly Grease (NLGI grade 2)NLGI certification of "GC-LB"; petroleum base oil and lithium complex thickener; 3 percent molybdenum disulfideOptimum temperature range -18 C (0 F) to +80 C (+140 F). Molybdenum has a median particle size of 3 microns.

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

Procedures

3
Determining the cause of a plugged fuel filter (ice or wax) diagnostic
  1. Remove the fuel filters.
  2. Cut the fuel filters open.
  3. Inspect the fuel filter before the filter warms. The inspection will show that the filter is filled with particles of either ice or wax.
Changing to Cat ELC maintenance

⚠ Do not leave an empty SCA maintenance element on a system that is filled with ELC. The element housing may corrode and leak causing an engine failure.

⚠ Improper or incomplete rinsing of the cooling system can result in damage to copper and other metal components.

⚠ The cooling system cleaner must be thoroughly flushed from the cooling system. Cooling system cleaner that is left in the system will contaminate the coolant. The cleaner may also corrode the cooling system.

Tools: Caterpillar cleaner for cooling systems, 5P-3413 Pipe Sealant, Suitable containers to collect fluids

  1. Drain the coolant into a suitable container.
  2. Dispose of the coolant according to local regulations.
  3. If equipped, remove the empty SCA maintenance element and the element base. Plug the coolant lines or bypass the coolant lines.
  4. Flush the system with clean water in order to remove any debris.
  5. Use Caterpillar cleaner for cooling systems in order to clean the system. Follow the instructions on the label.
  6. Drain the cleaner into a suitable container. Flush the cooling system with clean water.
  7. In systems with heavy deposits, disconnect the hoses. Clean deposits and debris from the hoses and fittings. Install the hoses and tighten the hose fittings.
  8. Fill the cooling system with clean water and operate the engine until the engine is warmed to 49 C to 66 C (120 F to 151 F).
  9. Drain the cooling system into a suitable container and flush the cooling system with clean water.
  10. Repeat Steps 8 and 9 until the system is completely clean.
  11. Fill the cooling system with the Cat ELC.
  12. Operate the engine until the engine is warmed. While the engine is running, inspect the engine for leaks. Tighten hose clamps and connections in order to stop any leaks.
  13. Attach the Special Publication, PEEP5027, "Label" to the cooling system filler for the engine in order to indicate the use of Cat ELC.
Calculating the amount of lighter fuel required to modify the cloud point or the pour point operation
  1. Obtain the specification for the cloud point or the pour point of both fuels from your fuel supplier.
  2. Locate the cloud point or the pour point of the heavier fuel on the left side of the table. Mark the point on the table.
  3. Locate the cloud point or the pour point of the lighter fuel on the right side of the table. Mark the point on the table.
  4. Draw a line between the two points that were established. Label this line "A".
  5. Find the lowest outside temperature for machine operation on the left side of the table. Draw a horizontal line from this point until it intersects line "A". Label this new line "C".
  6. Mark the intersection of line "C" and line "A". Draw a vertical line to the bottom of the table. Label this line "B". The point at the bottom of line "B" reveals the percentage of lighter fuel that is

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 Caterpillar CM25-8?

The Caterpillar CM25-8 has a displacement of 163.0 liters.

Which generators use the Caterpillar CM25-8 engine?

The Caterpillar CM25-8 powers 1 generator set(s), including Caterpillar CM25.