Caterpillarexcavator

Caterpillar 325 L

Maintenance schedule, common problems & OEM parts breakdown

The Caterpillar 325 L is a mid-size hydraulic crawler excavator in the roughly 25 to 28 tonne class, built around the Cat 3116T turbocharged diesel: an inline-six, 6.6 liter engine rated near 125 kW (168 hp) net at 2000 rpm. Operating weight runs about 26.5 to 28.2 metric tons (58,500 to 62,100 lb) depending on counterweight, track shoe width, and undercarriage length. Cat built the 325 L through the 1990s as part of its early medium-excavator lineup, following the standard 325 and ahead of the 325B family that took over later in the decade. Buyers could order the machine as the 325 L with a longer undercarriage (49 track links per side and wider grouser shoes) for extra stability, or as the 325 LN with a narrow 600 mm track gauge for confined-site work and lower ground pressure.

The 325 L sits at Cat's transition from purely mechanical excavators to the electronically managed engines that followed in the 325B and later C, D, and F generations, which stepped up to uprated 3116TA and successor engines running at higher rated speeds with tighter emissions control. Because the 325 L predates those emissions systems, its fuel and injection system stay mechanically simple, which keeps diagnosis and field repair straightforward next to later electronic-engine models. That simplicity, a large installed base, and parts commonality with other 3116-powered Cat equipment keep 325 L units circulating in the used market: rental yards, developing-market fleets, and owner-operators who want a durable mid-size excavator without the cost or complexity of newer emissions hardware.

Below: full specifications, fluids & capacities, the factory service schedule, common service parts, verified fault codes, what owners discuss, attachment guidance, the complete assembly directory, and a serial-number reference. Complete parts lists with full OEM part numbers, exploded diagrams, quantities, and fitment data are available free in Heavy Parts AI.

Caterpillar 325 L specifications

Engine

Engine	Cat 3116, turbocharged 6-cylinder diesel, direct injection, in-line four-stroke. Some production and dealer records for this line list it as 3116TA (turbocharged-aftercooled).
Displacement	6.6 L (403 cu in)
Cylinders	6, in-line, turbocharged, direct injection
Power	Net 168 hp (125 kW) at 2000 rpm. Gross approx. 177 hp (132 kW). Varies by configuration/series.
Emissions tier	No EPA/Tier certification. Built through the 1990s, ahead of U.S. nonroad Tier 1 standards for this power class.

Weights

Operating weight	27-28.2 t (59,500-62,100 lb). Varies by configuration/series (undercarriage length, counterweight, bucket selection).
Ground pressure	Not documented for this generation in available spec records.

Dimensions

Transport dimensions (L x W x H)	11.78 m x 3.38 m x 3.25 m (38 ft 8 in x 11 ft 1 in x 10 ft 8 in)
Tail swing radius, track shoe width, ground clearance, undercarriage length	Not documented for the standard L undercarriage in available spec records.

Performance

Max dig depth	7.29 m (23 ft 11 in)
Hydraulic system flow	124 GPM (469 L/min) combined pump flow to boom, stick and bucket circuits
Max reach, max dump height, max cutting height, swing speed, travel speed, gradeability, drawbar pull	Not documented for this generation in available spec records.

Forces

Bucket digging force	164.6 kN (37,000 lbf)
Arm/stick digging force	Not documented for this generation in available spec records.

Service capacities (summary)

Fuel tank, hydraulic system, engine oil, cooling system

Not documented for this generation in available public spec records. Confirm against the operation and maintenance manual for the specific serial number range.

Values vary by configuration, region, and serial range — confirm against your machine before planning transport or lifts.

325 L fluids & capacities

System	Capacity	Recommended fluid
Engine crankcase (with filter)	Approx. 20 L (5.3 US gal) with filter change, for the Cat 3116 turbocharged diesel fitted to the 325 L. This figure carries over from the shared 3116-family engine block used across the 1994-1998 325/325 L/325 LN line; confirm against this machine's own refill table before servicing.	Cat DEO diesel engine oil. SAE 10W-30 for ambient -18C to 40C (0F to 104F); SAE 15W-40 for -10C to 50C (14F to 122F). A commercial API CD/CE-class oil is an acceptable substitute where Cat DEO isn't stocked.
Cooling system	Approx. 32 L (8.4 US gal), typical for the 3116-powered 325-family cooling system. Not independently confirmed for this exact serial range - verify against the OMM.	Cat DEAC (Diesel Engine Antifreeze/Coolant), mixed 50/50 with water for freeze protection to -37C (-34F); a 60/40 concentrate mix extends protection to -52C (-62F). Later-production units in this family can be converted to Cat ELC extended-life coolant instead of DEAC.
Fuel tank	Approx. 420 L (111 US gal), the figure recurring across 325-family reference sources for this size class.	No. 2-D diesel fuel meeting the era's ASTM D975 specification. No branded fuel additive is required for normal factory operation.
Hydraulic system total AND hydraulic tank	Total hydraulic system approx. 310 L (82 US gal), based on the shared 325-family hydraulic circuit. Tank-only volume is not separately documented in the sources checked; expect it to run roughly half the system total. Confirm both figures against the OMM before a full system refill.	Cat TDTO transmission/drive train oil: SAE 10W below about 4C (40F) ambient, SAE 30 in moderate climates, SAE 50 above roughly 32C (90F). This predates Cat HYDO Advanced, which is the preferred hydraulic fill on later-generation Cat excavators.
Final drive (each)	Approx. 7.9 L (2.1 US gal) per side, drawn from the shared 325-family final drive housing capacity.	Cat TDTO, same viscosity-by-climate grades as the hydraulic system: SAE 10W cold, SAE 30 moderate, SAE 50 hot.
Swing drive	Approx. 10 L (2.6 to 2.7 US gal).	Cat TDTO, same viscosity-by-climate selection as the final drive and hydraulic system.
Pilot/other circuits	Not separately listed in the sources checked; the pilot circuit draws from the main hydraulic reservoir rather than a dedicated tank.	Same Cat TDTO fill as the main hydraulic system.
Grease (spec only)	N/A - spec only, no reservoir capacity applies.	Cat Prime Application Grease (NLGI 2, 3% moly) for swing gear, boom/stick pin joints and general linkage under moderate load; step up to Cat Extreme Application Grease (NLGI 1 or 2, 5% moly) for heavy digging or high-impact duty. In cold climates below roughly -20C (-4F), use Cat Extreme Application Grease-Arctic.

Capacities are refill values from factory literature — always fill to the dipstick/sight gauge, not the number.

Caterpillar 325 L maintenance schedule

Service interval	Tasks
Every 10 h	Check engine oil level and top off before starting the shift. Check coolant level at the sight glass; never open a hot radiator cap. Inspect the hydraulic tank sight gauge and add fluid if below the cold mark. Drain water and sediment from the fuel tank and the primary fuel filter/water separator. Walk the machine and check for fresh leaks at hoses, cylinders, and the swing bearing. Grease boom, stick, and bucket linkage pins, and check track sag and tension weekly.
Every 250 h	Change engine oil and replace the engine oil filter. Replace the primary and secondary fuel filters. Clean or replace the air filter primary element and check the safety element condition. Check alternator and fan belt tension and condition. Check swing drive and final drive oil levels. Pull an engine oil sample for analysis before draining.
Every 500 h	Replace the hydraulic oil return-line filter. Change the swing drive gear oil. Inspect and clean the radiator, oil cooler, and hydraulic cooler fins. Check track shoe bolt torque and overall undercarriage wear. Clean the hydraulic tank breather. Check swing bearing bolt torque.
Every 1,000 h	Change the final drive gear oil in both travel motors. Check and adjust engine valve lash. Inspect the turbocharger for shaft play and oil leakage. Test coolant condition and additive concentration. Inspect alternator and starter motor connections. Check the hydraulic pump and control valve for external leakage.
Every 2,000 h	Change hydraulic tank oil unless extended-life fluid and sample data support running longer. Change engine coolant if running conventional coolant rather than an extended-life type. Inspect swing bearing bolt torque and gear backlash. Inspect boom, stick, and bucket pins and bushings for wear; replace as needed. Inspect fuel injection lines and connections for seepage. Check the condition of cab mounts and structural welds on the upperstructure.
Every 4,000 h	Inspect the main hydraulic pump for wear via case-drain flow test and rebuild seals as needed. Inspect the swing motor and gearbox for internal wear: noise, backlash, or leakage. Evaluate undercarriage components (rollers, idlers, sprockets, chain) for replacement. Change extended-life coolant if due per additive test results. Inspect boom and stick cylinder rod seals for wear.
Every 8,000 h	Plan an engine top-end or inframe overhaul based on oil-analysis trends and compression/blow-by checks. Rebuild or replace worn undercarriage components (rollers, idlers, sprockets, track chain) as a set. Rebuild the swing gearbox and bearing if backlash or leakage is significant. Rebuild or replace the main hydraulic pump and travel/swing motors if efficiency has dropped. Inspect and repair boom and stick structural wear points and pin bores.

Servicing the 325 L beyond the schedule

Predictive Maintenance & Fluid Analysis

Run scheduled oil analysis on the 3116T engine, swing drive, final drives, and hydraulic tank rather than relying on hours alone. Watch iron and chromium trends for early turbocharger and injection pump wear, and check coolant additive concentration since standard coolant, not extended-life, is common on machines this age. Track hydraulic filter differential pressure to catch main pump wear before it shows up as sluggish boom or swing response, and log undercarriage wear percentages at each track inspection to plan rebuild timing.

Corrective & Common Repairs

Grinding or knocking during slew points to swing gearbox bearing or gear wear; weak swing torque with normal pressure usually means motor wear. Sluggish or uneven cylinder movement traces back to main pump seal and v-packing wear from age and heat cycling. The mechanical 3116T fuel system is prone to injection pump linkage wear and filter restriction, so treat rough idle or power loss as a fuel-system check first. Boom and stick pin bores loosen with age; bushing replacement restores linkage tolerances.

Overhaul & Rebuild Points

A well-serviced 3116T typically reaches 10,000 to 15,000 hours before needing a top-end or inframe overhaul; use oil-sample trends and blow-by checks to time the rebuild rather than guessing. Undercarriage components (rollers, idlers, sprockets, track chain) wear on a similar high-hour timeline and are usually replaced as a set for even wear. Budget for a swing gearbox and main hydraulic pump rebuild in the same window, since both see continuous duty cycles on this machine.

Seasonal & Environment Servicing

Cold climates need fuel conditioner or a winter-blend diesel to prevent gelling in the mechanical injection pump, plus a check of glow-plug or ether starting aids before freeze-up. Loosen track tension slightly for frozen or muddy ground to avoid overstressing sprockets and idlers. In hot, dusty conditions, clean radiator, oil cooler, and hydraulic cooler fins more often than the standard interval and shorten the air filter service cycle. In humid or coastal use, check cab wiring, connectors, and control valve exteriors for corrosion given the age of these machines.

325 L fault codes & troubleshooting

Code	Meaning	Likely cause	What to do
100-01	Engine oil pressure sensor signal below normal operating range (low oil pressure)	Low oil level, plugged oil filter, worn oil pump, or a faulty oil pressure sensor/wiring	Stop the engine at once, check oil level and look for external leaks before restarting
110-00	Engine coolant temperature sensor signal above normal operating range (overheat)	Low coolant level, blocked radiator core or screen, failed thermostat, or weak water pump	Reduce engine speed to low idle, let the engine cool, then check coolant level and radiator screen
168-04	Electrical system (battery) voltage below normal, shorted low	Weak or discharged battery, failing alternator/charging circuit, or corroded/loose connections	Check battery terminals, ground straps, and alternator drive belt before further electrical diagnosis
190-08	Engine speed/timing sensor signal abnormal (frequency/pulse fault)	Damaged, fouled, or misaligned speed-timing sensor, or a wiring/connector fault	Inspect sensor air gap, connector, and harness for damage before replacing the sensor
91-02	Throttle position sensor signal erratic or intermittent	Worn or damaged throttle linkage/sensor, or a loose connector	Inspect throttle linkage travel and the sensor connector for damage or looseness
111-01	Engine coolant level sensor signal below normal range (low coolant)	Coolant leak or system not filled to the correct level	Check coolant level at the sight glass or tank and inspect hoses/radiator for external leaks
Flash Code 55	No active diagnostic codes detected since the key switch was turned on	Not a fault - confirms the engine self-diagnostic system found no active faults	Use to verify the flash-code readout is functioning before trusting a no-fault result; check logged codes separately with a service tool
Hydraulic oil temperature warning lamp / gauge red zone	Hydraulic oil temperature has reached the high-temperature warning range on the monitor panel	Low hydraulic oil level, dirty oil cooler fins, overworking the machine, or a cooling fan fault	Reduce work load, idle the machine to cool, then check hydraulic oil level and cooler for debris

Codes and remedies are general guidance for this model family — always confirm with diagnostic tooling and your dealer before major repairs.

325 L attachments & work tools

Buckets

Standard general-duty (GP) bucket capacity for this class runs roughly 1.5-1.7 m³ (2.0-2.2 cu yd), with the broader GD/HD lineup for the size class spanning about 1.0-2.5 cu yd depending on width and application. Common widths run 610 to 1830 mm (24 to 72 in). Heavy-duty and rock buckets use thicker plate, cast/bolt-on cutting edges and extra wear protection for denser material; pin-on mounting is standard, with coupler-mounted buckets sized to match whichever coupler pin group is fitted.

Hydraulic hammers

The 325 L sits in the 19-26 ton (roughly 25-34K lb) breaker class. Typical hammer weight class for this size machine is about 1,360-1,800 kg (3,000-4,000 lb) with a tool/chisel diameter near 140 mm (5.5 in). Operating pressure for breakers in this range is commonly cited around 160-180 kg/cm² (approx. 2,270-2,560 psi) with impact rates near 350-550 bpm; exact figures vary by hammer brand and model.

Quick couplers

Both mechanical (pin-grabber/wedge) and hydraulically powered couplers are used on this size class for fast tool changes between buckets, hammers and grapples. Reported pin sizing for the coupler linkage on 324/325-class machines is around 90 mm, while bucket-only pins for this class are commonly 80 mm — pin size varies by configuration and coupler brand, so match to the machine's actual linkage before ordering.

Thumbs/grapples

Hydraulic and bolt-on thumbs mount to the stick to add clamping capability for sorting, loading and placing irregular material such as rock, stumps and debris. Rotating hydraulic grapples (360° rotation) are also available in this size class for log, rock and debris handling. Exact bracket and cylinder sizing for the 325 L specifically is not well documented — confirm stick mounting dimensions with the attachment supplier or dealer before ordering.

Rippers

Single-shank rippers are available for excavators in this size class, mounted in place of the bucket on the same pin group. They are used for breaking hard or frozen ground and light rock ahead of digging, and sizing (shank thickness, penetration depth) scales with the machine's size class.

Hydraulic kit notes

The 325 L's base main hydraulic circuit delivers flow to about 235 l/min (62 gpm) combined at pressure to 343 bar (about 4,975 psi), with pilot flow to about 36 l/min (9.3 gpm) at 41 bar. That is standard implement flow, not a dedicated high-flow attachment circuit. Hammers need a matched auxiliary line and pressure relief; rotating grapples and tiltrotators typically need a continuous-rotation (unrestricted return) auxiliary circuit. Machines of this vintage commonly did not come with factory auxiliary/hammer plumbing as standard, so verify whether the specific unit already has an auxiliary kit installed or needs one added before fitting hammers or grapples.

All 325 L assemblies by section

Every catalogued assembly group for the Caterpillar 325 L. Open an assembly to preview the parts inside — full OEM part numbers are available in Heavy Parts AI.

Telescopic Stick And Clamshell

Clamshell Bucket Assembly

Clamshell Bucket Cylinder Assembly

Clamshell Bucket Piping

Free Joint Assembly

Front Lubrication System

Hose Reel Assembly-Part 2 Of 3

Hose Reel Assembly-Part 3 Of 3

Hose Reel Assembly-Part 1 Of 3

Telescopic Cylinder--Part 3 Of 3

Telescopic Cylinder-Part 1 Of 3

Telescopic Cylinder-Part 2 Of 3

Telescopic Piping

Telescopic Stick Assembly

325 L serial number reference

On the 325 L the PIN/serial plate is riveted to the upper frame on the right-hand side near the base of the cab; Caterpillar also stamps the number directly into the frame at the same spot as a backup if the plate is lost. The PIN reads as an 8-character block: a 3-character prefix (identifies the model/build series and the plant that built it) followed by a 5-digit sequence number for that specific machine within the range.

Prefix	Identifies	Notes
2JK	325 L, standard undercarriage	USA-built plant group. Covered by its own 325/325L service manual range starting 2JK00001. Engine per family sourcing is the turbocharged Cat 3116.
6KK	325 L, standard undercarriage	Japan-built plant group. Grouped with sibling Japan prefixes in a combined 325/325L parts catalog. Engine per family sourcing is the turbocharged Cat 3116.
9KL	325 L, standard undercarriage, track-type	Japan-built plant group. Service literature explicitly names it a 325 L track-type excavator range (9KL00001-up) fitted with the Cat 3116 engine.
8NK	325 L, standard undercarriage	USA-built plant group. Service literature explicitly names it a 325L excavator range (8NK00001-up); family sourcing ties the model to the turbocharged Cat 3116.
7CJ	325 L, standard undercarriage, track-type	Japan-built plant group. Service literature explicitly covers 325 and 325L track-type excavators from 7CJ00001-up; also appears in a combined parts catalog with other Japan-built prefixes.
7LJ	325 L, standard undercarriage (also spans 325 and 325 LN coverage)	Belgium-built plant group. The factory manual for this range explicitly lists coverage for 325, 325L, and 325LN together, so the 7LJ range spans more than one nameplate designation.
2SL	325 L, standard undercarriage - confirm with dealer	Belgium-built plant group. One listing ties this range to 325L; another ties the same prefix to 325LN. Designation conflicts between sources - confirm exact variant with a dealer PIN lookup.
7LM	325 L, standard undercarriage (also covers an FM forest-machine swing variant)	USA-built plant group. Besides the standard 325L, this range is also cited for a 325-A FM L forest-machine/log-loader swing configuration sharing the same prefix block.

Frequently asked questions

What engine does the Caterpillar 325 L use?

The 325 L runs the Cat 3116T, a turbocharged inline-six diesel displacing 6.6 liters (403 cu in), rated at roughly 125 kW (168 hp) net at 2000 rpm. That is the earlier mechanical 3116T rating; the later 325B-family machines moved to an uprated 3116TA running at a higher rated speed.

What is the operating weight of the Caterpillar 325 L?

Operating weight runs about 26.5 to 28.2 metric tons (58,500 to 62,100 lb). The exact figure varies by counterweight, track shoe width, and whether the machine carries the standard L undercarriage or the narrower LN configuration.

What replaced the Caterpillar 325 L?

Caterpillar replaced the 325 L with the 325B family, including the 325B L and 325B LN, later in the 1990s. The nameplate continued through the 325C, 325D, and 325F generations and remains in production today as the Next Generation 325.

What 325 L owners discuss

What engine is in the Cat 325 L, and how reliable is it in the field?

The 325 L is documented in Cat sales literature and dealer parts records against the 3116 turbocharged diesel, an inline-six rated near 125 kW (168 hp) gross, not the larger 3306 fitted to some other Cat excavators of the same era. Always confirm off the machine's own dataplate, since resale listings mix up 325-family variants. Field reports on this engine describe it as light and fuel-efficient when maintained. Two wear points come up repeatedly: injector tip O-rings and injector sleeve seating are the most common cause of a rough-running or smoking engine that gets mistaken for a head gasket or ring problem, and the oil cooler and water pump are sealed with O-rings prone to weeping oil or coolant over time. Turbo failures usually trace back to oil starvation or contamination rather than a bad unit out of the box.

Why would a 325 L feel sluggish across every function at once instead of just one?

Owners describe the 325 L's main pumps sharing a common housing in an open-center, pilot-operated hydraulic circuit. When every function slows down together rather than just one, the usual troubleshooting order is to verify pilot pressure first (roughly 500 psi / 34 bar at the test port near the pilot accumulator), check hydraulic filters and oil condition, and rule out a pinched or chafed pilot hose before condemning a main pump. Pulling a pump on a hunch is discouraged, since a weak pilot signal or dirty oil produces the same symptom and is far cheaper to fix.

The machine won't auto-idle up when running the boom, stick, or bucket, but idles up fine while tracking. What's the fix?

This is a recurring 325 L complaint. Separate pilot-pressure switches near the main control valve tell the ECM to raise idle for travel, boom-raise, and the implement/swing circuit independently. Since idle-up still works while tracking, the fault points at the implement/swing switch rather than the whole circuit. Field technicians confirm this by dropping to low idle, then disconnecting and bridging each switch's harness terminals in turn; bridging the failed switch raises idle immediately, which isolates a bad switch from a wiring or ECM fault. The same generation is also known for monitor panel and gauge dropouts traced to corroded harness connectors, or on machines that have taken on cab water, a corroded ECM/monitor connector. Check connections before replacing the panel.

What undercarriage wear pattern should an owner expect, and does the "L" designation change anything?

The L designates the long-undercarriage version of the base 325, running a longer track frame with more links per side than the standard-frame machine for added stability and flotation. Wear pattern is otherwise typical for this roughly 27 t (60,000 lb) class machine: sprockets and idlers wear fastest, and roller and link condition track with hours and ground conditions more than time alone. Judge remaining undercarriage life by link and pin height plus roller flange wear, not the hour meter by itself. Machines worked on rock or demolition rubble show noticeably faster undercarriage wear than dirt or utility work.

Final drives on this class of machine keep needing rebuilds. What actually causes it?

Across the Cat medium-excavator line the 325 family belongs to, techs opening up a failed final drive keep finding the same recurring causes: gear oil left too long between changes damaging the planetary gear set, contaminated gear oil taking out the drive coupler, and hydraulic-side contamination reaching the drive motor itself. The consensus among people who rebuild these is that final drive life tracks gear-oil service intervals and filter quality more than raw hour count. Running cheap or infrequently changed filters is named as a leading cause of early failure.

The boom or stick creeps down on its own when parked or holding a load. How serious is this, and what causes it?

Treat any uncommanded boom or stick drop as a safety issue, not a nuisance. Owners describe a stick that free-falls under its own weight, traced to a worn holding or check valve, or a cylinder seal bypassing internally, rather than a structural problem. One field check some mechanics use is running an infrared thermometer over the cylinder barrel during a hold test; a hot spot points to fluid bypassing the seals internally under pressure. Because this affects load-holding with a raised boom or stick, have your dealer verify the holding valve and cylinder seal condition before working the machine near people or under a suspended load.

What should a buyer check specifically on a used 325 L before purchase?

Beyond the general excavator checklist (weld condition around the boom and stick pins, cold start behavior, fluid color and level, joystick and pedal feel), a few 325 L-specific points are worth extra attention. Pull the final drive covers or sample gear oil for metal given this drive's known failure pattern. Run the boom, stick, and bucket to see if auto-idle responds, since a flat response points at a worn pilot-pressure switch rather than a bigger problem. Run every function at once to check for an across-the-board slowdown that would flag pump or pilot-pressure trouble. Hold the boom and stick up unsupported for several minutes and watch for drift, which signals a worn holding valve or cylinder seal. Inspect the main wiring harness connectors near the cab and ECM for corrosion, especially on machines showing any sign of water intrusion in the cab. Confirm the engine and configuration against the dataplate rather than the sales listing, since 325-family model designations get mixed up in resale listings.

Compiled from owner and technician discussions across the industry — experiences vary by serial range and machine history.

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