John Deere LT155 Repair Guide: Parts, Diagrams, Manuals

The John Deere LT155 lawn tractor is an industrious mower, but when it won’t start, keeps breaking deck belts, or leaves uneven stripes because the deck is out of adjustment, it needs to be dealt with as quickly as possible.

You may not want to drag it to a dealer for every issue, but you also don’t want to guess on parts or risk damaging the Kohler engine or transaxle.

This guide walks LT155 owners through model‑specific maintenance, common problems, parts checklists, and troubleshooting so you can order the right parts online and get back to mowing with confidence.

And See:

• John Deere LT 155 Serial Number Lookup
• John Deere L100 Series Guide

Specs overview for the John Deere LT155

Use these specs as a check when you’re checking part descriptions or fluid types.

Core LT155 specs (high‑level)

• Tractor type: Lawn tractor for residential mowing.

• Engine: Petrol (gasoline), single‑cylinder or V‑twin Kohler Command vertical‑shaft engine (model varies by year/spec).

• Engine power: Around 11.2 kW (≈15 hp).

• Power source: Petrol, gravity‑feed fuel system.

• Transmission: Hydrostatic transaxle (variable speed, foot‑controlled).

• Cutting deck: Typically 38‑inch or 42‑inch mower deck, belt‑driven from the engine PTO.

• Weight: About 215 kg (approx. 474 lb).

Because the LT133, LT155 and LT166 share a family platform, you’ll often see them grouped in the same technical manual, but certain parts (belts, blades, some engine components) are model‑specific.

Always select “LT155” in catalogs rather than assuming LT133/LT166 parts fit.

Summary: Key John Deere LT155 parts and fluids

These are generic names so you can choose genuine or aftermarket parts, but specs must match your engine, deck size, and transaxle.

John Deere LT155  Fluids

• Engine oil: Petrol engine oil, typically 10W‑30 meeting the manufacturer’s spec for air‑cooled small engines.

• Fuel: Unleaded petrol meeting current standards; avoid stale fuel.

• Grease: Multi‑purpose or polyurea grease for spindles, steering, and chassis lubrication.

• Transaxle: Many LT155 hydrostatic axles are sealed units with lifetime fill; check your manual before attempting any fluid change.

John Deere LT155  Filters and tune‑up items

• Engine oil filter to LT155/Kohler spec.

• Fuel filter (in‑line filter).

• Engine air filter (and pre‑cleaner foam element where fitted).

• Spark plug(s) to Kohler spec.

John Deere LT155 Common wear parts

• Mower blades (standard/high‑lift or mulching, correct length and hole pattern for deck size).

• Deck drive belt(s) (engine‑to‑deck and deck‑to‑blades, depending on configuration).

• Traction/drive belt from engine to transaxle.

• Deck idler pulleys and spindle bearings.

• Ignition switch and key.

• Battery (12 V lawn/garden, correct physical size).

Always match parts by “John Deere LT155”, your deck size (e.g. 38″ deck), and your engine model code from the engine tag, because belt lengths and filters can differ even within the LT series.

How to identify your John Deere LT155 (model and serial number plates)

Before ordering parts or following model‑specific instructions, confirm you have an LT155 and record both the tractor serial number and the engine model.

Where to find the tractor ID plate

On the LT155 lawn tractor:

• The tractor identification plate is usually located on the frame at the rear of the tractor, near or under the seat area or on the rear bumper/frame cross‑member.

• It lists the model (LT155) and the tractor serial number (PIN).

Where to find the engine model and spec

Kohler engines carry their own tag or stamp, typically:

• On the blower housing/shroud of the engine.

• On a decal on the side of the engine.

It will show a model (e.g. “Kohler Command CV…”), spec number, and serial, which you should use when ordering engine‑specific parts like carburetors, coils, and tune‑up kits.

John Deere LT155  – How to use these IDs when buying parts

When using parts sites or catalogs:

• Always select John Deere LT155 first, then choose your deck size and configuration.

• For engine parts, select by Kohler engine model/spec rather than just “LT155”.

• For belts and blades, confirm deck size (e.g. 38″ vs 42″) and style (side discharge vs mulching kit).

This avoids ordering LT133/LT166 belts or filters that look similar but are the wrong length or spec.

Typical problems owners search for with the John Deere LT155

Common LT155 issues reported in guides, manuals, and repair videos include:

• No‑start or hard‑start (often stale fuel, bad carb, or safety switches).

• Cranks but won’t fire, or only runs with choke on.

• Mower won’t move (drive belt or hydro linkage issues).

• Deck not engaging or blades stopping under load (belt, idlers, or PTO switch/lever).

• Repeated deck belt failures and poor cut quality.

• Uneven cutting, scalping, or deck vibration (deck level, blades, or spindles).

• General 25‑, 50‑, and 100‑hour maintenance tasks (oil, filters, belts, greasing).

The sections below cover routine service and then walk through troubleshooting for: starting issues, PTO/deck engagement, drive/traction problems, and cut quality/overheating in the deck area.

Maintenance schedule overview for the John Deere LT155

Exact intervals depend on your conditions (dust, heat, slopes), but typical guidance is:

Before each use / every 8–10 hours

• Check engine oil level.

• Check fuel level and inspect for leaks.

• Inspect tyres and steering linkage visually.

• Check for loose deck parts or exposed belts.

• Verify operator‑presence and brake safety systems work.

Every 25–50 hours

• Change engine oil (often first change at 5 hours, then 50 hours, then every 50 or annually).

• Inspect and clean air filter and pre‑cleaner.

• Grease front axle and steering points.

• Clean engine cooling fins and shrouds if accessible.

Every 100 hours (or as stated)

• Replace engine oil filter (if not done more frequently).

• Replace fuel filter.

• Replace air filter element.

Seasonally / annually

• Sharpen or replace mower blades.

• Inspect and replace deck and drive belts if cracked or glazed.

• Clean underside of the deck.

• Check and adjust deck level and pitch.

• Inspect battery and charge or replace as needed.

Sticking to these intervals drastically reduces breakdowns such as “no‑start after winter”, “keeps throwing deck belts”, and overheating of the engine from clogged fins.

Step‑by‑step: core John Deere LT155 maintenance tasks

Engine oil and filter change (LT155)

Why it matters: The air‑cooled Kohler relies on clean oil for cooling and lubrication; neglected oil changes are a leading cause of early engine failure.

Parts and supplies (generic):

• Engine oil 10W‑30 (or as per manual) suitable for air‑cooled petrol engines.

• Engine oil filter to LT155/Kohler spec.

• New drain plug washer (if required).

• Drain pan, rags, basic tools.

Summary steps:

1. Run the engine for a few minutes to warm the oil, then park on level ground, set parking brake, and shut off the engine.

2. Remove the key and allow the engine to cool enough to work safely.

3. Place a drain pan under the oil drain valve or plug.

4. Open the valve/remove the plug and let oil drain completely.

5. Remove the oil filter, taking care of any spillage.

6. Wipe the mounting surface and lightly oil the new filter’s gasket.

7. Install the new filter hand‑tight plus the specified fraction of a turn.

8. Close the drain and add the correct amount of fresh oil.

9. Start the engine, check for leaks, then shut off and verify oil level.

Using the correct viscosity helps with hot‑weather protection and cold‑start lubrication; too thin or too thick oil can cause rapid wear or hard starting.

John Deere LT155

John Deere LT155 Fuel and air filter maintenance

Why it matters: Stale fuel, clogged filters, and dirty air elements are the main causes of poor running, surging, and carburetor damage on LT155s.

Parts (generic):

• In‑line fuel filter (LT155 spec).

• Primary air filter element and foam pre‑filter (if equipped).

• New hose clamps if existing ones are corroded.

Fuel filter steps:

1. Clamp or pinch off the fuel line from the tank to prevent spills.

2. Place a rag below and remove the old in‑line filter.

3. Install the new filter with the flow arrow pointing toward the carburetor.

4. Secure with clamps and release the fuel line clamp.

5. Check for leaks after starting.

Air filter steps:

1. Remove the air filter cover on the engine.

2. Clean out any debris in the housing.

3. Replace the paper element if dirty; wash and lightly oil the foam pre‑filter if the manual specifies.

4. Reinstall components and ensure a good seal so dust does not bypass the filter.

After fuel filter changes, the LT155 usually self‑primes, but if it won’t start, recheck fuel flow and the condition of the carburetor and fuel.

John Deere LT155  – Greasing and chassis lubrication

Why it matters: Steering, front axle, and deck pivots wear quickly without grease, leading to sloppy steering, uneven cut, and noisy operation.

Parts and supplies:

• Multi‑purpose or polyurea grease suitable for lawn equipment.

• Grease gun.

Key grease points:

• Front axle pivot.

• Steering spindles/kingpins.

• Tie‑rod ends (if fitted with grease fittings).

• Some mower deck spindles and idlers (if greaseable—some later spindles are sealed).

Grease at least every 25–50 hours, and more often in dusty or wet conditions.

John Deere LT155 Deck and drive belt inspection

Belts are high‑wear items on the LT155 and are a frequent source of “no drive” or “PTO won’t engage” complaints.

Parts (generic):

• Deck drive belt (engine to deck).

• Deck blade belt (on some decks).

• Traction drive belt (engine to hydrostatic transaxle).

• Idler pulleys and tension springs if worn.

Checks:

• Inspect belts for cracks, glazing, fraying edges, or signs of slipping.

• Check idler pulleys for smooth rotation and play.

• Ensure belt routing matches the diagram in the manual or on the deck.

Replacing belts with the correct LT155/deck‑specific part number is critical; belts that are slightly too long or short will slip or eat pulleys.

Troubleshooting: John Deere LT155 won’t start or runs poorly

Starting issues are very common, especially on machines that have sat over winter.

Common causes

• Stale or contaminated fuel.

• Clogged fuel filter or blocked fuel line.

• Dirty or failed carburetor.

• Dead battery or bad solenoid.

• Faulty safety switches (seat, brake, PTO).

• Dirty air filter or fouled spark plug.

Likely parts

• Fuel filter and fresh fuel.

• Spark plug(s).

• Battery and possibly starting solenoid.

• Carburetor rebuild kit or replacement carburetor (matched to Kohler model).

• Safety switch(es), e.g., seat switch, brake switch.

Step‑by‑step checks

1. Fuel quality and flow

   • Drain old fuel if it smells sour or looks dark; refill with fresh petrol.

   • Pull the line at the carb and check that fuel flows freely when you open the tank valve.

2. Battery and starting circuit

   • Check that the battery is charged; replace if it will not hold voltage.

   • If you hear only a click, suspect a failing solenoid or poor ground.

3. Safety switches

   • Ensure brake/clutch is fully depressed and PTO lever is OFF when starting, as required by the manual.

   • If the engine cranks only when you wiggle the seat or brake, a switch may be loose or failing.

4. Air and spark

   • Inspect and replace the spark plug if fouled, worn, or incorrect gap.

   • Replace a heavily contaminated air filter.

5. Carburetor

   • If the engine only runs with choke on, surges, or will not idle, the carburetor likely has varnish or debris; cleaning or rebuilding is often needed.

If you are not comfortable rebuilding carburetors, a pre‑matched replacement for your Kohler model/spec can be a straightforward fix, but you must order by engine model and spec, not just “LT155 carb”.

Troubleshooting: John Deere LT155 Deck/PTO not engaging or losing drive

On the LT155, deck engagement is typically mechanical via a belt and idler system (or manual PTO lever) rather than an electric clutch on some variants, but the exact setup depends on the deck and year.

Common deck/PTO issues

• Deck belt off, worn, or broken.

• Idler pulley seized or tension spring broken.

• PTO lever cable out of adjustment or broken.

• Safety interlock preventing engagement (on electric PTO variants).

Likely parts

• Deck drive belt (correct length for LT155 and deck size).

• Idler pulleys and tension spring.

• PTO lever cable or linkage parts.

• Electric PTO clutch or switch (if so equipped; many LT155s use mechanical engagement).

Step‑by‑step checks

1. Visual inspection

   • Remove the key and disconnect the spark plug before working under the tractor.

   • Check the belt routing against the deck diagram; ensure the belt is on every pulley correctly.

2. Belt condition

   • Replace belts that are cracked, glazed, or stretched.

   • Use belts specified for “LT155 with [your deck size]”, not universal belts.

3. Idlers and spindles

   • Spin idlers and spindles by hand; any grinding, wobble, or stiffness means replacement is needed.

4. PTO lever and linkage

   • Ensure the PTO engagement lever moves smoothly and fully.

   • Adjust cable/linkage so the belt is fully tensioned in the ON position.

If the deck still will not engage or blades stall easily despite good belts and pulleys, suspect a slipping engine PTO pulley, incorrect belt, or on electric‑PTO variants, a failing electric clutch, which should be replaced with the correct LT155‑compatible unit.

Troubleshooting: John Deere LT155 won’t move (drive issues)

Drive problems are typically caused by a failed or derailed traction belt, hydrostatic linkage issues, or a worn hydro transaxle.

Common causes

• Traction drive belt broken, stretched, or off pulleys.

• Idler pulley seized or tension spring broken in the drive belt path.

• Parking brake linkages stuck partly on.

• Hydrostatic transaxle low on oil (where serviceable) or internally worn.

Likely parts

• Traction/drive belt correct for LT155.

• Drive idler pulleys and springs.

• Control linkage bushings and hardware.

• Replacement hydrostatic transaxle (worst‑case scenario).

Step‑by‑step checks

1. Safety first

   • Shut off engine, remove key, and block wheels before working under the tractor.

2. Belt and pulleys

   • Inspect the drive belt from engine pulley back to the hydro transaxle pulley.

   • Replace any belt that is loose, cracked, or oil‑soaked.

3. Linkages and brake

   • Verify that the pedal returns fully and the brake mechanism releases completely; a cable or linkage that doesn’t return can feel like a failed transaxle.

4. Hydro feel

   • If the engine pitch changes when you press the pedal but the tractor barely moves, and belts and linkages are fine, the hydrostatic transaxle may be worn; this is often a dealer or specialist repair.

Drive belt replacement is a very common LT155 DIY job; just be careful to route the new belt exactly as shown in the manual or under‑hood diagram.

Troubleshooting: John Deere LT155 – poor cut quality, vibration, and deck overheating

Uneven cut, scalping, vibration, and belt overheating around the deck are all common LT155 complaints.

Common causes

• Dull, bent, or mismatched blades.

• Deck not level side‑to‑side or front‑to‑back.

• Worn spindle bearings.

• Deck plugged with old grass and debris.

• Belt slipping from worn pulleys or incorrect belt.

Likely parts

• Correct LT155 mower blades (standard or mulching).

• Deck drive belt(s).

• Spindle assemblies or bearings.

• Deck idler pulleys.

Step‑by‑step checks

1. Blades

   • Inspect blades for nicks, bends, and wear.

   • Replace in sets with blades rated for your deck model and width.

2. Deck cleaning

   • Safely support the tractor and deck; clean the underside to remove built‑up grass. Excess buildup causes uneven cutting and belt strain.

3. Deck level

   • Follow the manual’s procedure to set side‑to‑side level and front‑to‑rear pitch, typically with a deck leveling gauge or ruler at specified reference points.

4. Spindles and pulleys

   • Check spindle shafts and pulleys for play and roughness; replace worn parts.

A clean, correctly leveled deck with sharp blades and proper belt tension will run cooler, cut more evenly, and put less stress on the engine and belts.

Expanded parts checklists for John Deere LT155 owners

Seasonal/annual service kit (generic names)

• Engine oil (10W‑30) and correct oil filter.

• Fuel filter.

• Air filter and pre‑cleaner.

• Spark plug(s).

• Multi‑purpose grease cartridges.

• Mower blades set (correct for LT155 deck).

• Deck belt(s) and drive belt if due or obviously worn.

Starting/ignition repair parts

• 12 V lawn/garden battery (correct size).

• Starter solenoid (if clicking/no crank).

• Ignition switch and key.

• Spark plug(s).

• Carburetor kit or replacement carb matched to Kohler engine model.

Deck/PTO system parts

• Deck drive belt (engine to deck).

• Blade belt (if separate).

• Idler pulleys and tension springs.

• PTO lever cable or linkage parts.

• Mower deck leveling gauge (helpful add‑on).

Drive and chassis parts

• Traction drive belt.

• Drive idler pulleys and springs.

• Steering tie‑rod ends and spindle bushings.

• Front wheel bearings/tyres.

For each category, confirm the parts listing is specifically for John Deere LT155, not just “LT series”, and check any serial or deck‑size notes before buying.

When to DIY vs when to call a professional

Good DIY jobs for an LT155 owner

• Engine oil and filter changes.

• Fuel and air filter replacement.

• Spark plug changes and basic carburetor cleaning.

• Deck and drive belt replacement (with patience).

• Blade replacement and deck leveling.

• Basic electrical fixes like replacing a battery or ignition switch.

Jobs better suited to a workshop

• Carburetor rebuilding if you’re not experienced (tiny passages and adjustments).

• Internal hydrostatic transaxle repairs.

• Engine internal repairs (valves, head gasket, crankshaft).

• Major frame or deck weld repairs.

• Complex wiring harness diagnostics.

If you’re unsure, it’s often worth paying for a diagnostic to avoid stacking expensive, wrong‑fit parts and chasing the wrong problem.

Known/common John Deere LT155 issues and quirks

Owners and repair content highlight a few recurring LT155 themes:

• No‑start after long storage due to stale fuel, bad carb, and dead battery.

• Repeated deck belt failures from mis‑routed or incorrect belts, worn pulleys, or clogged deck.

• Drive belt and idler wear leading to “no drive” or slow climbing on slopes.

• Engine stalling or backfiring from fuel issues or ignition problems.

• Rear transaxle and frame wear on machines that have been heavily worked with towing or slopes.

Most of these are manageable on a DIY basis with good preventive maintenance and by using correctly specified belts and parts.

FAQ: John Deere LT155 maintenance and repair

1. What oil does a John Deere LT155 use?
   Typically a 10W‑30 petrol engine oil approved for air‑cooled small engines, as specified in the LT155 operator’s manual; avoid automotive oils that do not meet small‑engine specs.

2. How often should I change the oil on an LT155?
   Usually first at around 5 hours, then every 50 hours or yearly, whichever comes first, or more often in dusty or hot conditions.

3. What size mower deck does an LT155 have?
   Most LT155s use a 38‑ or 42‑inch deck; you must know your exact deck size, since belts and blades differ between them.

4. How do I know which belts to order for my LT155?
   Match belts by “John Deere LT155” plus your deck size and configuration; never rely on belt length alone or on LT133/LT166 part numbers.

5. Why does my LT155 crank but not start after sitting all winter?
   Commonly stale fuel, clogged carburetor, or a weak battery; draining fuel, replacing the fuel filter, cleaning the carb, and fitting a fresh battery often solve it.

6. Why does my LT155 only run with the choke on?
   This usually indicates a partially blocked carburetor main jet or fuel passage; cleaning or rebuilding the carburetor is often required.

7. How often should I change the fuel filter on an LT155?
   Many guides suggest every 100 hours or annually, and any time you have fuel contamination issues.

8. Why does my LT155 keep breaking deck belts?
   Common causes are wrong‑size belts, mis‑routing, seized idlers, rough pulleys, or a deck packed with grass; replacing with the correct belt and fixing idlers usually stops repeat failures.

9. How do I level the mower deck on an LT155?
   With the tractor on flat ground, use a measuring gauge at the blade tips and adjust side‑to‑side and front‑to‑rear linkages according to the operator’s manual.

10. What battery does a John Deere LT155 use?
    A 12 V lawn/garden‑type battery sized to fit the LT155 battery tray; match physical dimensions and cold‑cranking amps to the parts listing.

11. Why won’t my LT155 move even though the engine runs fine?
    A broken or derailed drive belt, seized idler, or a stuck brake linkage are common causes; if belts and linkages check out, the hydrostatic transaxle may be worn.

12. How often should I sharpen or replace blades on an LT155?
    At least once per season for light use, more often in sandy or rough conditions; replace if badly nicked, bent, or worn thin.

13. Can I use generic mower blades or belts on my LT155?
    Yes, but only if they are explicitly listed as compatible with the LT155 and your deck size; incorrect generic parts can cause poor cut, vibration, or repeated belt failures.

14. How do I safely support the LT155 for deck or belt work?
    Park on level ground, set the brake, remove the key, block wheels, and use jack stands or ramps rated for the machine—never rely only on a jack.

15. Is the LT155 hydrostatic transaxle serviceable?
    Some versions are effectively sealed “lifetime” units; any major internal work is typically done by a specialist or via transaxle replacement rather than DIY fluid changes.

16. Where should I look up LT155 parts diagrams?
    Use official John Deere online parts catalogs and search by model (LT155) and serial, or reputable parts sites that provide exploded diagrams and compatibility filters.

17. What’s the single best way to keep my LT155 out of the repair shop?
    Stick to regular oil and filter changes, keep belts and blades in good condition, use fresh fuel, and clean the deck and engine cooling fins frequently, especially in dusty conditions.

1. LT155 won’t start or is very hard to start

Typical symptoms: cranks but won’t fire, backfires on start, needs full choke all the time, or only starts after repeated cranking.

Likely causes

• Stale or contaminated fuel after storage.

• Clogged in‑line fuel filter or restricted fuel line.

• Dirty or partially blocked carburetor jets/passages.

• Weak battery or failing starter solenoid.

• Faulty safety switches (seat, brake, PTO interlocks).

• Fouled or incorrect spark plug, ignition coil beginning to fail.

Fixes and checks

1. Fuel and filter first

   • Drain old fuel if it smells sour or looks dark; refill with fresh petrol.

   • Replace the in‑line fuel filter and confirm strong flow to the carburetor.

2. Battery and crank circuit

   • Fully charge the battery or replace if it won’t hold charge.

   • If you only get a click, inspect cables, grounds, and the solenoid.

3. Spark and ignition

   • Install a new spark plug gapped to Kohler spec.

   • If the engine runs 10–20 minutes then dies hot and restarts when cool, suspect an ignition coil that opens when hot and replace it.

4. Carburetor cleaning/replacement

   • If it only runs on choke, surges, or backfires at idle, remove and clean the carb (jets, bowl, passages), or fit a replacement carburetor matched to your Kohler model and spec number.

5. Safety switches

   • Confirm brake/clutch is fully depressed and PTO is off when starting.

   • If starting is intermittent depending on seat position or pedal travel, test/replace the relevant switch.

Common parts involved: fuel filter, fresh fuel, spark plug(s), battery, ignition coil, carburetor kit or replacement carb, seat/brake/PTO safety switches.

2. Runs for 10–20 minutes, then sputters and dies

Very classic LT155 complaint: mower runs fine cold, then sputters, backfires, and stops after 15–20 minutes, and often starts again once cool.

Likely causes

• Ignition coil failing when hot (internal windings open when heated).

• Fuel cap not venting, causing vacuum in the tank.

• Restricted fuel filter or line, especially under sustained load.

Fixes

1. Eliminate fuel starvation causes

   • Replace the fuel filter and inspect fuel lines for kinks, cracks, or debris.

   • Clean/replace the fuel cap; make sure the vent hole is clear.

2. Test/replace the ignition coil

   • If fuel flow is good and the engine loses spark when hot, replace the coil with one matched to your Kohler engine model.

Owners and repairers widely consider a hot‑failing coil one of the LT155’s most common “runs 20 minutes then dies” faults.

3. LT155 won’t move, moves weakly, or loses drive

Symptoms: engine runs, but tractor barely moves or not at all; forward and reverse both weak; or you know the belt broke.

Likely causes

• Ground/traction drive belt worn, stretched, or snapped.

• Drive idler pulley seized or badly worn.

• Tension spring broken or missing.

• Parking brake not fully releasing or linkage issues.

• Worn or failing hydrostatic transaxle (less common than belt issues, but possible).

Fixes

1. Inspect the ground drive belt and pulleys

   • Safely support the tractor, block wheels, and inspect the belt from engine to transaxle.

   • Replace the drive belt if it is cracked, glazed, oil‑soaked, or loose; route exactly per the manual.

2. Replace worn idlers and springs

   • Any idler that feels rough, wobbly, or seized should be replaced along with its partner idlers as a set if practical.

   • Install a new tension spring if stretched, broken, or missing.

3. Check brake and linkages

   • Verify the brake/clutch pedal returns fully and the parking brake releases completely; adjust or lubricate linkages as needed.

4. Hydrostatic transaxle

   • If belt and linkages are correct and the tractor still barely moves, the hydro could be worn or internally damaged; diagnosis and replacement are usually workshop jobs.

Common parts: ground drive belt, drive idler pulleys, tension spring, brake linkage hardware, in severe cases a replacement hydro transaxle.

4. Deck won’t engage or blades stop under load

Symptoms: pull PTO lever and nothing happens; blades start then quickly slow or stop; belts jump off.

Likely causes

• Deck belt routed incorrectly, stretched, or broken.

• Idler pulley seized or worn; tension spring weak.

• PTO lever linkage out of adjustment or cable damage.

• On some configurations, electric PTO clutch or switch issues.

Fixes

1. Check belt routing and condition

   • Compare routing to the decal on the deck or diagram in the manual; mis‑routing is common after belt changes.

   • Replace belts that are cracked, shiny, or clearly stretched, using an LT155‑specific belt for your exact deck width.

2. Inspect idlers and tensioner

   • Spin idler pulleys by hand and replace any with noise or wobble.

   • Replace weak or broken tension springs and ensure the tension arm moves freely.

3. Check PTO lever and linkage

   • Confirm the lever fully engages; adjust cable or linkage per the manual so the belt is tight when PTO is on.

4. Electric PTO (if equipped)

   • If you have an electric clutch, test the PTO switch, wiring, and clutch coil; replace faulty components with LT155‑compatible parts.

Common parts: deck drive belt(s), idler pulleys, tension springs, PTO lever cable, PTO switch/clutch (where fitted).

5. Repeated deck belt failures and poor cut quality

Repeatedly throwing or burning belts and getting a rough or uneven cut is a major LT155 headache.

Likely causes

• Wrong belt (for a different LT model or deck size).

• Worn or rough pulleys cutting into the belt.

• Blades seized on spindles or spindles with bad bearings.

• Deck out of level, packed with debris, or bent hangers.

Fixes

1. Correct belt, correct routing

   • Order belts specified for “John Deere LT155” plus your deck size (38″ or 42″).

   • Follow the routing diagram exactly, paying attention to which side of each idler the belt runs.

2. Refresh deck hardware

   • Replace idler pulleys that are noisy or wobble; they often kill belts by misalignment or heat.

   • Replace bent or damaged belt guides and retainers so the belt cannot jump off.

3. Spindles and blades

   • Check spindle shafts for play; replace spindles or bearings if loose or rough.

   • Install a fresh set of correct‑spec blades (not mixed or generic odd lengths) and balance if sharpening.

4. Level and clean the deck

   • Scrape built‑up grass from under the deck and level it side‑to‑side and front‑to‑rear using the manual procedure.

Common parts: deck belt(s), idlers, belt guides, spindle assemblies or bearings, matched blade set.

6. Engine backfires, runs rough, or won’t idle

Owners report backfiring on start/idle and rough running that often traces to fuel mixture, carb condition, or ignition timing via the coil.

Likely causes

• Carburetor mixture screws misadjusted or jets partially blocked.

• Vacuum leaks around carb or intake gaskets.

• Ignition coil breakdown causing intermittent spark.

• Incorrect or fouled spark plug.

Fixes

1. Carburetor service and adjustment

   • Clean the carburetor thoroughly or rebuild; remove bowl and jets and clear passages.

   • Adjust mixture screws per the manual—often start from baseline turns out, then fine tune warm.

2. Check for air leaks

   • Inspect carb mounting bolts and gaskets; replace gaskets if cracked or hard.

3. Ignition components

   • Install new spark plug(s); if misfire/backfire persist, test and replace the ignition coil if spark drops out hot.

Common parts: carburetor kit or replacement, intake gaskets, spark plug(s), ignition coil.

7. Rear/transaxle wear or failure

On older LT155s, owners sometimes encounter weak pull, noisy rear end, or suspected “bad rear”.

Likely causes

• Long‑term wear or internal failure of the hydrostatic transaxle.

• Contaminated or low oil in serviceable variants.

• Heavy towing or steep slopes beyond design intent.

Fixes

• Rule out belts and linkages first – most “bad rear” complaints are actually belt or idler problems.

• If the rear remains weak or noisy with correct belts and linkages, the realistic fix is usually a replacement transaxle or professional rebuild rather than DIY internals.

Common parts: replacement hydrostatic transaxle assembly; sometimes used units or rebuilds are sourced from mower recyclers.

8. Smaller but frequent issues

From owner reports and resource pages, a few other recurring LT155 annoyances appear:

• Ignition switch/key failures – engine won’t shut off or intermittent starting, fixed by replacing the key switch.

• Deck rust and repeated deck replacement – some owners report replacing decks after years of use due to rust through.

• Muffler guard/baffle problems – flimsy guards bending or interfering under hard turns.

• Cracked fuel tank or cap – especially on older machines, fixed by tank repair/replacement and new cap.

These are mostly straightforward DIY fixes if you match parts to LT155 and check serial notes on the parts diagram.

Quick reference: most‑common LT155 fixes and parts

LT155 carburetor adjustment for backfiring