Cat C1.7 Specifications
| Engine Model: Caterpillar C1.7 |
| Engine Type: 4-cycle inline 3-cylinder direct injection liquid-cooled diesel |
| Total Displacement: 104 cu.in (1.7 L) |
| Rated Engine Power: 28-48 Hp (21-36 kW) at 2500 rpm |
| Aspiration Type: Naturally aspirated |
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The Caterpillar C1.7 is a compact,
high-efficiency, three-cylinder industrial diesel engine designed for
small construction equipment, agricultural machinery, mobile industrial
equipment, and compact generator sets. As part of Caterpillar’s
small-bore engine lineup, the C1.7 emphasizes low fuel consumption,
minimal emissions, ease of service, and consistent torque delivery at
low-to-mid operating speeds. It is widely used in compact excavators,
mini skid steers, small telehandlers, turf equipment, compressors,
pumps, and portable power units.
The C1.7 was engineered to deliver reliable performance in harsh
environments while meeting stringent emissions requirements (Tier 3,
Tier 4 Final, Stage V depending on configuration). Its straightforward
mechanical layout, reinforced cast-iron components, direct injection,
and high structural stiffness ensure long engine life even in
continuous-duty industrial settings. Despite its small displacement, the
C1.7 demonstrates strong torque output and is valued for its
exceptionally compact form factor.
The Caterpillar C1.7 is a four-stroke, water-cooled, inline
three-cylinder diesel engine with direct injection. Total displacement
is approximately 1.7 liters (104 cubic inches). Bore is 84 mm (3.31 in),
and stroke is 90 mm (3.54 in). This long-stroke configuration enhances
low-speed pulling power, fuel efficiency, and stable combustion
characteristics. Compression ratio varies from 19.0:1 to 23.0:1
depending on emissions controls.
Power ratings vary by application:
– Industrial equipment: 30–48 hp (22–36 kW) at 2,200–3,000 rpm
– Agricultural machines: 28–45 hp (21–34 kW)
– Generator-drive versions: 18–35 kW standby power at 1,500–3,000 rpm
Peak torque output usually ranges: 95–135 Nm (70–100 lb-ft) at
1,600–1,800 rpm. Idle speed is generally 850–950 rpm. Maximum governed
speed varies between 2,400 and 3,000 rpm. Firing order is 1-3-2.
The crankshaft is forged steel, supported by four main bearings for
stable rotational dynamics. Pistons are cast-aluminum alloy with
reinforced crowns and direct-injection combustion bowls. Piston rings
include two compression rings and one oil-control ring. Connecting rods
are forged steel with replaceable bearing inserts. The camshaft is
gear-driven and located in the block.
The cylinder block is a cast-iron parent-bore design, with thick
cylinder walls capable of multiple honing and oversize rebuilds. The
block includes substantial ribbing to reduce distortion and improve
vibration control. Coolant passages fully surround the cylinders for
uniform heat distribution, even under prolonged high-load operation.
The cylinder head is cast iron and incorporates direct-injection
combustion chambers. Each cylinder uses two valves—one intake and one
exhaust—operated by rocker arms and pushrods from the gear-driven
camshaft. Hardened valve seats ensure long-term durability.
Typical valve-lash (cold):
– Intake: 0.20–0.25 mm (0.008–0.010 in)
– Exhaust: 0.30–0.35 mm (0.012–0.014 in).
The C1.7 uses a mechanical direct-injection system or an electronically
modulated mechanical injection system depending on production year and
emissions level.
Fuel system components include:
– Mechanical lift pump
– Primary water separator
– Fine paper-element fuel filter
– Inline or rotary mechanical pump
– Multi-hole or pintle-type injectors
Injection pressures typically range 160–300 bar depending on injector
type.
Fuel-system maintenance:
– Replace fuel filters every 250–300 hours
– Drain water separator regularly
– Service injectors every 1,000–1,500 hours
– Verify injection timing during major overhaul
The C1.7 uses a high-efficiency wet-sump lubrication system. A
gear-driven oil pump draws oil from the sump through a pickup screen and
sends it through a full-flow filter before entering the lubrication
galleries.
Oil capacity typically: 4.5–5.5 liters (4.7–5.8 qt)
Normal operating oil pressure: 300–420 kPa (44–61 psi)
Idle pressure: 80–150 kPa (12–22 psi)
Recommended oil viscosities: SAE 10W-30 or 15W-40 depending on climate
and emissions system. Oil change intervals are normally 250 hours in
industrial equipment.
Cooling is provided by a belt-driven centrifugal water pump circulating
coolant through the block, cylinder head, radiator, and optional oil
cooler. A thermostat begins opening around 82°C (180°F) and is fully
open at 95°C (203°F).
Cooling capacity: generally 5–7 liters (5.3–7.4 qt)
System pressure: 70–90 kPa (10–13 psi).
| Intake and Exhaust Systems |
Air intake systems differ by equipment:
– Construction equipment: heavy-duty dual-stage filters
– Agriculture: cyclone pre-cleaner options
– Stationary engines: enclosed canister filters
Turbocharging is optional on some emissions packages, improving torque
and power density.
Exhaust manifolds are cast iron with high thermal resistance. Tier 4
versions incorporate diesel oxidation catalysts (DOC) and additional
exhaust aftertreatment.
| Electrical and Starting Systems |
The C1.7 supports 12-volt and some 24-volt configurations. Alternators
typically produce 30–60 amps. Starter motors range 1.5–2.5 kW.
Electronic versions include sensors for:
– Coolant temperature
– Oil pressure
– Fuel temperature
– Intake-air temperature
– Crankshaft position.
Depending on OEM installation, the C1.7 may
support:
– PTO drives
– Hydraulic pump drives
– Generator heads
– Auxiliary belt-driven equipment
– Emissions aftertreatment systems
– Remote cooling configurations.
Approximate engine dimensions:
– Length: 500–600 mm (19.7–23.6 in)
– Width: 420–480 mm (16.5–18.9 in)
– Height: 620–700 mm (24.4–27.6 in)
Dry weight: 130–160 kg (287–353 lb).
– Oil and filter: every 250 hours
– Fuel filter: every 250–300 hours
– Air filter: inspect every 50 hours; replace as needed
– Coolant: replace every 2 years
– Valve adjustment: every 1,000 hours
– Injector inspection: 1,000–1,500 hours
– Compression testing: 2,000 hours
– Belt inspection: every service interval.
– Cylinder head bolts: 70–80 Nm (52–59 lb-ft)
– Main bearing caps: 90–110 Nm (66–81 lb-ft)
– Connecting rods: 45–55 Nm (33–41 lb-ft)
– Flywheel bolts: 95–115 Nm (70–85 lb-ft)
– Crankshaft pulley bolt: 140–160 Nm (103–118 lb-ft)
– Oil drain plug: 25–35 Nm (18–26 lb-ft)
– Injector hold-down bolts: 20–25 Nm (15–18 lb-ft).
The Caterpillar C1.7 is widely used in:
– Compact excavators
– Mini skid-steer loaders
– Small telehandlers
– Agricultural sprayers and compact tractors
– Industrial pumps and compressors
– Mobile hydraulic power units
– Generator sets
– Ground-support equipment.
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