FS25_RealisticMechanicalSystems

In-depth vehicle wear, failure, diagnostics, maintenance, and repair system for Farming Simulator 25.

Every machine is built from up to 8 individual systems, each with its own condition, its own wear factors, and its own way of failing. Service on schedule, work the machine within its limits, and watch for the early symptoms: the cheapest repair is always the one you catch first.

Singleplayer, multiplayer, and dedicated server.

Electric vehicles are not supported yet.

Note: This repository is an independently maintained fork of Advanced Damage System by id577, developed by Squallqt since 30 June 2026. The gameplay model and the documentation have been substantially reworked since then; the original credits and provenance are preserved unchanged in NOTICE.md.

Quick Start

Three rules are enough to play without constant breakdowns:

1. Follow the service interval. Around 5 operating hours on average by default. Check it in the workshop, in the vehicle info panel, or in the fleet menu (P key), then run Maintenance.
2. Prepare your machines daily. Hold R near a vehicle for a pre-shift check, clean it with the Air Blower, and grease what needs greasing with the Grease Gun.
3. Do not abuse your equipment. If it would damage a real machine, it damages this one: overloading, overheating, cold-engine work, wheel slip in mud, oversized implements, speed over rough ground.

Core Mechanics

Every system tracks three values.

• Condition: health and remaining service life. It sets how much abuse a system tolerates before failures become likely. It drops about 1% per operating hour under normal use, faster under harsh use, and very slowly on a vehicle stored outdoors. Restored by Overhaul.
• Stress: accumulated misuse. It does not build during normal operation, only through overload, overheating, cold running, wheel slip, and system-specific mistakes. Breakdown probability rises as Stress approaches that system's current Condition. Reduced by preventive maintenance, by repairs, and automatically once a breakdown occurs.
• Service: the state of oils, filters, and fluids. It falls with operating hours, and a low level accelerates Condition loss across every system, the engine most of all. Restored by Maintenance.

Inspection reports give an approximate status (OPTIMAL, REQUIRED, OVERDUE). Exact percentages require a full defectoscopy, which is slow and expensive, and rarely worth it: following the recommended interval works better than measuring.

Wear Factors

Normal wear depends on system activity. Hydraulics and PTO wear only while active; the other enabled systems retain their idling and downtime wear. Overdue service adds wear while the affected system operates, and poor-quality consumables increase overall Condition wear.

System	Wear factors
Engine	Load above 85%; air filter clogged past 50%; cold running below 50C at high RPM load; overheating above 95C under load; oil level under 50%
Transmission	Sustained pull above 85% load, with an accumulation window scaling from 30 to 90 seconds; lugging (high load, low RPM); wheel slip above 5% under 20 km/h; heavy trailer below 10 hp/t (6 hp/t for trucks); a load held on oil below 45C; on CVT, overheating above 100C; oil level under 50%
Hydraulics	Pump running whenever the engine runs; lifted implement mass on the linkage; vibration while carrying an implement over rough ground; qualified hydraulic movement; cold oil proxy below 30C; hot oil proxy above 90C; fluid level under 50%
Cooling	Thermostat past 95% open while the engine is more than 3C over its target; engine above 95C; cold shock below 50C at high RPM load
Electrical	Lights on; rain, snow, or hail on an outdoor vehicle; starter cranking; engine above 95C; vibration over rough ground at speed
Chassis	Poor lubrication on machines that require greasing; vibration over rough ground at speed; steering under 4 km/h, scaled by the steered angle and by the load the steered axle really carries; braking above 2 km/h while towing
Fuel	Fuel below 20% under load; fuel colder than 20C above 50% load; idling past 60 seconds; fuel consumption above 80% of the configured maximum
PTO	Active drive; continuous native PTO utilization above 55%, reaching its full overload factor at 90%; unique engagement cycles are recorded for fault selection without instant engagement damage

AI workers wear a machine exactly like a player. They are protected by behaviour instead: the helper slows down on overload or overheating, never stalls, and is never blocked by a hard start.

Breakdowns

Breakdown probability depends entirely on how close a system's Stress is to its Condition. Condition also sets the chance of a critical failure, one that appears straight at stage 4 and skips the rest. The type is not random: the mod tracks which wear factors have been active most and picks the failure that history makes most likely.

Most breakdowns run through four stages, Minor, Moderate, Major, and Critical, each costing more to repair than the last. Progression is context-dependent; some faults only worsen while the machine performs the work that causes them. Modern vehicles get dashboard indicators from stage 2, but stage 1 is silent and only shows itself through symptoms: fluctuating RPM, coloured exhaust smoke, knocking, squealing. Catching one there costs almost nothing.

Beyond individual failures, low Condition triggers a permanent General Wear and Tear effect: an old machine loses engine power, transmission bite, battery performance, and cooling efficiency even with nothing formally broken.

Reading the smoke

The exhaust plume is a real diagnostic channel, not decoration. Its colour comes from three mixed sources, its density from how bad things are.

Colour	What it means	Usual causes
Black	Too much fuel for the available air	A hard pickup before the turbocharger catches up, lugging at low revs, overload, clogged air filter, worn turbocharger, failing injectors, ECU fault
Blue	The engine is burning its own oil	Worn engine at low Condition, leaking turbocharger seals, valve train wear
White	Fuel leaving the engine unburnt	Cold engine, failed glow plugs, failing injection or a starving fuel system

Production year matters as much as condition. With the same fault, an older machine always smokes more, and a recent one running AdBlue shows almost nothing until something actually breaks. A cold start still shows on a recent machine, briefly, because high injection pressure and glow plugs improved far less than particulate control did.

The plume is drawn as real smoke particles, layered from a tight jet at the pipe to a slow trail behind. A clean plume dissipates at once; a loaded one hangs and takes seconds to clear. It follows the gas the engine actually moves, so it swells under boost and shrinks when the engine is coasting. On a turbocharged machine, black smoke appears whenever the fuel outruns the air: for a moment on a hard pickup while the turbocharger spools up, and for as long as it lasts on an engine held at full load down at low revs. A naturally aspirated engine never shows either, since without boost its air flow follows the engine speed alone.

Leaving a diesel idling also leaves its mark. Past a long idle under 30% load, unburnt carbon builds up and darkens the plume. The deposit survives an engine stop and a save, then burns off only once the engine is warm and working under load.

Full breakdown list

Breakdown	Applies to	Critical effect
ECU Malfunction	Non-electric, 2000+	Engine cannot be controlled and will not start
Corroded Wiring	2000+ with lights	Lights dead, engine start impossible
Battery Sulfation	All	Cranking too weak to start reliably
Glow Plug Failure	Diesel	No start when preheating is required
Alternator Regulator Failure	All	No charging, battery reserve only
Turbocharger Wear	Engines from 56 kW (75 hp)	Most engine power lost, further damage likely
Oil Pump Malfunction	All non-electric	Oil circulation lost, running and starting unsafe
Valve Train Malfunction	All non-electric	Engine cannot run correctly, may not start
Manual Clutch Wear	Manual transmissions	Clutch burnout, vehicle cannot move
Synchronizer Malfunction	Manual and synchro-shift	Shifting impossible
Powershift Pump Malfunction	Powershift	Transmission stuck in neutral
CVT Chain Wear	CVT	Movement no longer reliable
CVT Control Valve Malfunction	CVT	Severely restricted emergency mode
CVT Addon Malfunction	Vehicles using CVT Addon	Complete CVT failure, vehicle cannot move
Transmission Thermostat Malfunction	CVT	Thermostat stuck at one opening, the oil either overheats or never warms up
Transmission Oil Leak	All non-electric	Too little oil left to run the transmission safely
Hydraulic Pump Malfunction	Vehicles with qualified hydraulic functions	Hydraulic system inoperable
Hydraulic Cylinder Internal Leak	Vehicles with a qualified hydraulic lift	Raised loads drop rapidly
Hydraulic Hose External Leak	Vehicles with declared hydraulic connections	Hydraulic performance strongly reduced
Hydraulic Filter Clogging	Vehicles with qualified hydraulic functions	Hydraulic functions barely respond
Hydraulic Oil Cooler Malfunction	Vehicles with qualified hydraulic functions	Active hydraulic work overheats the accepted oil-temperature proxy
Hydraulic Control Valve Malfunction	Vehicles with a qualified controllable hydraulic target	One qualified hydraulic function becomes erratic or blocked
PTO Drive Coupling Wear	Vehicles with a physical PTO output	PTO power can no longer be transmitted
PTO Drive Output Bearing Wear	Vehicles with a physical PTO output	PTO operation becomes impossible
PTO Engagement Control Malfunction	Vehicles with a physical PTO output	PTO engagement becomes unreliable, then impossible
Brake Malfunction	Wheeled	Braking impossible
Bearing Wear	Wheeled	Wheel rotation blocked
Steering Linkage Wear	Wheeled without tracks	Directional control unsafe
Track Tensioner Malfunction	Tracked	Running gear can seize
Thermostat Malfunction	All non-electric	Coolant circulation disrupted, overheating unavoidable
Coolant Leak	All non-electric	Safe engine temperature unreachable
Fan Clutch Failure	All non-electric	Cooling airflow insufficient
Fuel Pump Malfunction	All non-electric	No fuel delivered to the engine
Fuel Injector Malfunction	All non-electric	Engine will not run correctly, may not start
Fuel Filter Clogging	All non-electric	Fuel flow insufficient to run
Fuel Line Air Leak	All non-electric	Fuel supply cannot be maintained

Workshop

Four main procedures, plus fluid Top up, with options that change duration, cost, and quality. All of them take real time, and the workshop closes overnight: work in progress resumes the next opening. Planning when a machine goes in matters as much as paying for it.

• Inspection: Visual is quick but can miss things, Standard detects faults and reports condition, Complete Defectoscopy finds hidden faults and defective parts and gives exact values.
• Maintenance: replaces oils, filters, and fluids, and restores Service. Minimal is cheap and partial, Standard follows manufacturer spec, Extended restores above normal, Preventive also strips Stress from the worst systems. The cost is fixed, so servicing at 90% costs the same as at 10%.
• Repair: Quick Fix suppresses the symptoms without fixing the fault, which returns. Standard replaces the failed part and cuts Stress. Advanced replaces everything around it and zeroes Stress.
• Top up: fills whatever fluid the machine is missing, for the price of the fluids alone. Quick, and the button disappears once everything is full.
• Overhaul: restores Condition on one system or all of them, clears breakdowns, and includes maintenance unless partial. Partial, Standard, and Full differ in scope and price. Paintwork can be renewed for a fee. It never restores a flat 100%: the result depends on maintainability, on how many overhauls the machine already had, and on chance.

Maintenance and repair let you pick part quality between Used, Aftermarket, OEM, and Premium. Cheaper parts are more often defective: on maintenance they shorten the interval and accelerate wear, on repair they bring the same fault back. Complete Defectoscopy detects them.

Pre-Shift Care

• Pre-shift check: hold R near a vehicle for a go or no go verdict, the machine and its next service, the four fluid levels, radiator and air filter fouling, and reveal faults a real visual check would catch. Takes seconds, works anywhere.
• Fluids: engine oil, coolant, transmission oil and hydraulic fluid each have a level, read against the minimum mark of their gauge. Engine oil is burnt off with the work done, faster under load and much faster as the engine wears, so a healthy engine always reaches its next service above the mark whatever interval you set while a tired one asks to be topped up; the other three only drop through a leak. Under the mark the machine only asks for a top up and still works normally; it is under 50% that a machine short of coolant or transmission oil runs hot, and one short of engine oil or hydraulic fluid wears faster. The workshop Top up service fills what is missing for the price of the fluids, maintenance and overhaul replace everything, and a repair puts back what the fault it fixed had let out.
• Wrong fluid: manually transferring an incompatible product contaminates only the selected circuit. Depending on the proportion in the mixture, system wear can rise to three times its normal rate, heat can increase, and contaminated hydraulic fluid can slow hydraulic functions by up to 25%. The transfer requires explicit confirmation, and only a complete fluid replacement clears the contamination. Workshop procedures only reserve compatible products.
• Air Blower: clears dust from the cooling pack and the air filter. A clean radiator will not overheat. Blowing an air filter out only recovers part of it, since what is embedded in the media stays until maintenance replaces it, and washing the machine never touches it.
• Grease Gun: restores lubrication on machines that need it, harvesters above all. Lubrication drops 10% per period only if the machine was neither operated, greased, nor serviced during it; inspection alone does not count.
• Aiming a hand tool: point it directly at the machine within 5 m.

Reliability and Maintainability

Every brand carries two ratings based on its real-world reputation, both shown in the shop.

• Reliability slows Condition loss, lowers base breakdown probability, and lengthens service intervals. Premium European and American brands generally rate higher than budget or older Eastern European ones.
• Maintainability cuts the money and time of every workshop operation and improves how much an overhaul recovers. Simple older machines usually beat modern electronics-heavy ones.

Vehicles also age: production year drives thermostat behaviour, overheat protection, how much the machine smokes, and which breakdowns can occur at all.

Three settings cover the exhaust. Exhaust Smoke turns the model on or off and Smoke Intensity scales opacity from 100% to 300%, neither of them changing the calculated causes or colours; both belong to the server. Plume Detail belongs to each player instead: it sets how many layers of smoke their own machine draws, down to none, and never affects anyone else. It can only reduce what the server allows. Turning the model off restores the vehicle's native exhaust.

Buying Used

A used machine arrives with the wear its hours have earned, and it may carry a fault nobody declared. Nothing shows at the sale.

The hours set the odds, the brand shifts them:

Hours on the clock	Reliable brand	Budget brand
10 h	7%	11%
25 h	18%	28%
45 h	32%	51%

Run an Inspection before the machine sees any work. Standard finds most of it, Complete Defectoscopy finds all of it along with the exact condition of every system. Skipping that step is how a bargain becomes a breakdown in the middle of a field.

Thermal Model

Engine temperature is computed from load, ambient temperature, dirt on the radiator, airflow from speed, and thermostat state, and it feeds directly into wear and failure risk.

• Engine thermostat behaviour follows production year. Older machines have inert mechanical thermostats with real stiction; modern ones use fast PID control that adapts quickly to load.
• Overheat protection is staged from 2000 onwards: power is progressively limited, then the engine can shut down. Older vehicles have no such protection and can suffer a hard failure instead.
• Warm-up is mandatory. Cold oil only aggravates wear when the driveline is genuinely transmitting a heavy load. Idling and power used solely by an external consumer do not trigger cold-transmission wear.
• Transmission oil is not held at a target temperature. Like the real machines, its thermostat only decides whether the oil goes through the oil cooler or around it: around it while the oil is cold, through it as the oil warms. The temperature then floats with the job instead of holding one value.
• A low fluid level costs cooling. The minimum mark only asks for a top up, nothing changes there. Under 50% the coolant carries less heat away and the transmission cooler loses capacity with the oil, down to 15% on an empty circuit.
• CVT machines run a separate transmission model driven by the pump, the power take-off, transmission load, the hydrostatic ratio, wheel slip and acceleration. Slow high-stress work and jerky driving can cook a CVT while the engine still reads normal.
• Heat follows real simulation time. Engine and transmission temperatures are unaffected by the game time scale, cool independently after shutdown, and are preserved by savegames and multiplayer synchronization. Time spent outside the game is not simulated.

Electrical System

The battery is a real model, not a switch: capacity falls in the cold, internal resistance rises with cold and age, and charge acceptance drops with low temperature, high state of charge, and poor health. A weak battery does not merely hold less; it also charges worse, sags harder, and cranks poorly.

The alternator output follows engine RPM, current load, and its own health. When consumers demand more than it delivers, voltage sags and the battery drains. Battery temperature is simulated on its own, driven by ambient air, engine bay heat, and self-heating from current.

If a battery is too flat to start, jumper cables link both vehicles into a shared circuit so the donor can support cranking or charge the receiver.

Diesel preheating starts automatically below 25 C. It remains short in mild weather and lengthens progressively as the engine gets colder. At 5 C and above, failed glow plugs can make the start rough but do not block it solely because of preheating; below that point, their condition becomes start-critical.

Installation

1. Place the mod ZIP file into your FS25 mods/ directory (do not extract).
2. Activate the mod in mod selection.
3. Access RMS from the fleet menu (P key), the in-game settings, and workshop interactions.

Important: Do not run RMS and Advanced Damage System together. RMS steps aside when it finds ADS and leaves it in charge, so nothing runs twice. Removing ADS is enough: RMS then picks up the condition, the service history and the settings of your fleet from the savegame.

Usage

Running a service

1. Drive the vehicle to a workshop, or use a mobile workshop.
2. Pick Inspection first if you are unsure what is wrong, then Maintenance, Repair, or Overhaul.
3. Choose the scope and part quality; both change price and duration.
4. Read the report afterwards. The maintenance log keeps every past procedure.

Reading the warning signs

1. Watch the dashboard indicators, which light from stage 2 on modern vehicles.
2. Listen for knocking, whistling, and grinding, and read the exhaust: black means the engine is choking on fuel it cannot burn, blue means it is burning oil, white means fuel is leaving the engine unburnt. Stage 1 is otherwise silent.
3. Run a pre-shift check when something feels off, then a workshop inspection if it does not clear.
4. Repair early. A stage 1 fault costs a fraction of a critical one.

Console Commands

For testing and debugging. Most require you to be inside a vehicle that supports the mod. Typed on a client, they are relayed to the server.

Command	Description
rms_debug	Toggles debug mode
rms_listBreakdowns	Lists every breakdown ID in the registry
rms_addBreakdown [id] [stage]	Adds a breakdown to the current vehicle
rms_removeBreakdown [id]	Removes one breakdown, or all of them without an ID
rms_advanceBreakdown [id]	Advances one breakdown a stage, or all where possible
rms_setCondition <0.0-1.0>	Sets Condition on every enabled system
rms_setSystemCondition <system> <0.0-1.0>	Sets Condition on one system
rms_setSystemStress <system> <value>	Sets Stress on one system
rms_setSystemStressMultiplier <value> [system]	Sets the stress accumulation multiplier
rms_setService <0.0-1.0>	Sets the Service level
rms_resetVehicle	Resets condition, service, and active breakdowns
rms_reinitializeVehicle	Recomputes condition from vanilla resale price, as on first load
rms_setExcluded <true|false>	Excludes the vehicle or brings it back in; prints the exclusion state without an argument
rms_startService <type> [count]	Starts inspection, maintenance, repair, or overhaul
rms_finishService	Finishes the active service instantly
rms_getServiceState	Prints workshop and service state
rms_showServiceLog [index]	Prints the service log, or one entry in detail
rms_getDebugVehicleInfo [1]	Prints vehicle debug info, with specializations when given 1
rms_setDirtAmount <0.0-1.0>	Sets the dirt level
rms_setFuelLevel <value>	Sets fuel, as 0.0-1.0 or 0-100 percent
rms_setHorsePower <hp>	Sets engine power, rescaling the torque curve
rms_setPlowMaxForce <kN>	Sets max force on the selected or attached plow
rms_resetFactorStats	Resets accumulated factor statistics
rms_toggleHudDebugView	Switches the HUD debug view between normal and factor stats
rms_setConfigVar <path> <value>	Changes a value inside RMS_Config at runtime
rms_printSpecVar <path>	Prints a value from spec_RealisticMechanicalSystems
rms_setSpecVar <path> <value>	Changes a value inside spec_RealisticMechanicalSystems
rms_telemetryStart [scenario] [intervalMs]	Starts CSV telemetry (default, transmission, pto or exhaust)
rms_telemetryStop	Stops telemetry and closes the file

Valid system names for RMS console commands

Commands that take a system argument accept these names, case-insensitive:

• engine
• transmission
• hydraulics
• cooling
• electrical
• chassis
• fuel
• pto

This applies to commands such as rms_setSystemCondition, rms_setSystemStress, and rms_setSystemStressMultiplier.

Examples: rms_setSystemCondition engine 0.75, rms_setSystemStress fuel 0.2.

Temperature test commands

The raw values drive the physical model; the other two values are the smoothed dashboard readings. Set both members of a pair when preparing a controlled test:

rms_setSpecVar rawEngineTemperature 90
rms_setSpecVar engineTemperature 90
rms_setSpecVar rawTransmissionTemperature 90
rms_setSpecVar transmissionTemperature 90

Read the physical temperatures with:

rms_printSpecVar rawEngineTemperature
rms_printSpecVar rawTransmissionTemperature

Changelog

v0.10.0.0

• Renamed this independent fork to Realistic Mechanical Systems; existing Advanced Damage System saves and settings are migrated automatically
• Reworked used vehicles: condition follows the selected vehicle lifespan, hidden faults can exist at purchase, and reliable brands reduce the risk
• Added physical engine oil, coolant, transmission oil and hydraulic fluid: nine purchasable products in 5, 25 and 200 L containers, manual transfer, contamination and workshop stock; transmission oil leaks can drain the circuit
• Reworked the pre-shift check and workshop fluid service: go or no go verdict, next service, four level gauges and a Top up procedure charged by the missing volume
• Reworked air filter servicing: dusty work clogs the filter, the air blower only cleans it partly, washing does not clean it, and workshop maintenance replaces it; hand tools also reach further
• Added exhaust smoke driven by vehicle age, engine wear, load and active faults, with a local detail setting for each player
• Added tractor drivetrain management: 2WD, 4WD and AUTO modes, differential locks, an automatic parking brake and wind-up wear; Enhanced Vehicle takes over the functions it manages
• Expanded the HUD with tractor, towed and combined mass, dashboard indicators, and separate engine and transmission thermal alerts
• Added automatic diesel preheating in cold weather, with a four-stage glow plug breakdown
• Reworked transmission thermal wear: temperature responds to the pump, power take-off and heavy low-speed work; cold oil progressively increases wear only under real driveline load; CVT gearboxes can suffer thermostat failure
• Rebuilt hydraulic wear and breakdowns around actual machine capability, pump operation, lifted mass and vibration
• Added a dedicated power take-off system with drive coupling, output bearing and engagement control breakdowns
• Rebalanced mechanical wear: radiator clogging reduces cooling, cooling wear requires an engine above target temperature, cold-engine wear requires high load, turbo wear applies from 75 hp, steering follows angle and axle load, and lubrication covers every non-road machine
• Reworked vehicle eligibility and non-player vehicles: supported motorized machines are classified by capability, AI workers cause normal wear, and contract machines show hours without wearing down
• Improved idling: an unattended running engine now consumes fuel
• Added a global settings profile for new savegames and a fleet reset based on the selected vehicle lifespan; removed the thermal sensitivity, warm-up boost and cooling slowdown settings
• Removed the work process system, harvest wear and the unloading auger breakdown; production years are now resolved internally without Vehicle Years
• Reworked the workshop, inspection, report, maintenance log and leased-vehicle return interfaces; simplified the on-foot vehicle info box to condition and next service
• Expanded tutorial tips for the fluid, smoke, drivetrain, parking brake and thermal systems
• Added 12 languages (27 total) and improved existing translations

Support

• GitHub Issues
• GitHub Discussions

License

GNU General Public License v3.0. See LICENSE for the complete terms and NOTICE.md for provenance and attribution.