John Deere La135 Problems – Fix Common Issues And Restore Your Cut
Most John Deere LA135 problems stem from three main areas: fuel delivery, hydrostatic transmission wear, and deck maintenance. Common fixes include cleaning the carburetor to stop engine surging, purging the T40 transmission to restore drive power, and leveling the 42-inch deck to eliminate uneven cutting.
Routine maintenance—such as replacing the fuel filter, sharpening the blades, and using fresh, ethanol-free gasoline—can prevent over 80% of the mechanical failures reported by 100 Series owners.
Owning a John Deere LA135 means having a reliable 22-horsepower V-twin engine at your disposal for weekend yard work. We all appreciate the convenience of a riding mower, but mechanical hiccups can occasionally disrupt your landscaping schedule.
You want a lush, perfectly manicured lawn, and a malfunctioning tractor is the last thing you need. This guide provides the practical steps required to diagnose and repair your machine, ensuring it stays out of the shop and on the grass.
In the following sections, we will explore the most frequent john deere la135 problems and provide expert-level solutions for fuel systems, transmissions, and electrical components. By following these steps, you can extend the lifespan of your mower and maintain a professional-grade finish on your turf.
Common John Deere LA135 Problems You Might Encounter
The John Deere LA135 is part of the 100 Series, designed primarily for residential use. While these machines are robust, they often face specific challenges as they age or if maintenance schedules are ignored.
Homeowners often report issues with the engine surging, the mower “creeping” while in neutral, or a noticeable loss of power when climbing hills. These are not necessarily signs that your mower is dying; rather, they are symptoms of parts that need adjustment or replacement.
Understanding these john deere la135 problems allows you to approach repairs with confidence. Most issues can be resolved in your driveway with basic hand tools and a bit of patience. Let’s break down the primary systems that require your attention.
Engine Surging and Starting Difficulties
If your LA135 starts but runs unevenly—a condition often called “hunting” or “surging”—the culprit is almost always the fuel system. Modern gasoline with high ethanol content can gum up the small passages in the carburetor over time.
First, check your fuel filter. A clogged filter restricts the flow of gasoline, causing the engine to lean out and stall under load. Replace the filter annually as part of your spring tune-up to ensure a steady supply of fuel to the Briggs & Stratton engine.
If the filter is clean, inspect the fuel pump. On the LA135, the pulse-style pump relies on vacuum pressure from the crankcase. Ensure the vacuum line is not cracked or disconnected, as this will immediately stop fuel delivery.
Solving Hydrostatic Transmission Sluggishness
One of the more frustrating john deere la135 problems involves the Tuff Torq T40 hydrostatic transmission. Over time, you may notice the mower feels weak, especially after it has been running for thirty minutes and the oil has thinned out.
Heat is the primary enemy of hydrostatic drives. Ensure the cooling fan on top of the transaxle is intact and free of grass clippings. Use compressed air to blow out debris from the cooling fins to prevent internal components from overheating.
If the mower lacks power even when cold, you may need to purge the transmission. This process removes trapped air bubbles that interfere with hydraulic pressure. To purge, pull the bypass lever at the rear of the mower, start the engine, and alternate between full forward and full reverse several times.
Troubleshooting the 42-Inch Mower Deck
The quality of your cut depends entirely on the health of the mower deck. If you notice “stepping” in your lawn or patches of uncut grass, the deck likely needs a manual adjustment or new hardware.
Begin by checking the tire pressure. An under-inflated rear tire will tilt the entire machine, leading to an uneven cut that no amount of deck leveling can fix. Inflate all tires to the PSI specifications listed on the sidewall before adjusting the deck.
Inspect the mower blades for nicks or bends. Hit a hidden rock or a thick tree root, and you can easily throw a blade out of balance. This causes severe vibration that can eventually damage the spindle bearings and the PTO clutch.
Replacing the Drive and Deck Belts
Belts are wear items that naturally stretch and fray. If you hear a squealing noise when you engage the blades, your deck belt is likely slipping. Check the tensioner arm and the idler pulleys to ensure they move freely and apply proper pressure.
Replacing the drive belt is more labor-intensive but necessary if the mower fails to move. Look for “glazing” on the sides of the belt—a shiny, smooth appearance that indicates the belt has been slipping and generating excessive heat.
Always use OEM (Original Equipment Manufacturer) belts for the LA135. While generic belts may be cheaper, they often lack the specific length or “V” profile required for the John Deere pulley system, leading to premature failure.
Leveling the Deck for a Professional Finish
To level the deck, park the mower on a flat, level concrete surface. Measure the distance from the blade tip to the ground on both the left and right sides. Use the adjustment link on the left side of the deck to bring them within 1/8th of an inch of each other.
Next, check the front-to-back pitch. The front tip of the blade should be approximately 1/4 inch lower than the rear tip. This “rake” ensures that the grass is cut once and then discharged efficiently, preventing mulching drag that slows down the engine.
Electrical System and Safety Switch Failures
Electrical john deere la135 problems often manifest as a mower that won’t crank or an engine that dies the moment you engage the blades. These are frequently tied to the safety interlock system designed to protect the operator.
If the engine won’t turn over, check the battery voltage. A healthy battery should read at least 12.6 volts. If the battery is strong but you only hear a “click,” the starter solenoid may have failed or the ground wire may be corroded.
The seat safety switch is a common point of failure. If the internal spring weakens, the mower may “think” you have stood up and will kill the engine. Ensure the plug is firmly seated and the switch is not obstructed by debris under the seat cushion.
Maintaining the PTO Clutch
The Power Take-Off (PTO) on the LA135 is manual, meaning you engage the blades with a lever. If the blades fail to spin, check the engagement cable. These cables can stretch or snap over time, preventing the idler pulley from tightening the belt.
If the cable is intact but the blades still won’t turn, inspect the electric clutch (if equipped on certain sub-models) or the manual brake pad. The brake pad is designed to stop the blades quickly when disengaged; if it becomes stuck, it will create friction and heat.
Periodically lubricate the pivot points of the engagement linkage with a silicone-based lubricant. This ensures smooth operation and prevents the lever from becoming stiff or difficult to operate during long mowing sessions.
Essential Maintenance to Prevent Future Issues
The best way to handle john deere la135 problems is to prevent them through a rigorous maintenance schedule. Think of your mower like a small car; it requires fresh oil, clean air, and regular inspections to perform at its peak.
Change the oil every 50 hours of use or once per season. Use a high-quality 10W-30 or 15W-40 oil, and always replace the oil filter. This protects the internal bearings of the V-twin engine from the high heat generated during summer mowing.
Clean the air filter every 25 hours. If you mow in dusty conditions, you may need to do this more often. A clogged air filter forces the engine to work harder, increasing fuel consumption and causing the spark plugs to foul prematurely.
- Grease the Spindles: Use a grease gun to pump high-quality lithium grease into the deck spindles every 25 hours.
- Check Spark Plugs: Replace the spark plugs annually to ensure a strong spark and efficient combustion.
- Clean the Deck: Scrape away dried grass from the underside of the deck to maintain proper airflow and prevent rust.
- Inspect the Fuel Lines: Look for cracks or brittleness in the rubber lines that could lead to air leaks or fire hazards.
Safety First: Working on Your John Deere
Before attempting any repairs, prioritize your safety. Lawn mowers are powerful machines with sharp components that can cause serious injury if handled improperly. Always follow these basic safety protocols.
First, disconnect the spark plug wires. This is the only way to guarantee the engine cannot accidentally fire while you are turning the blades or working near the drive belt. It only takes a second and provides total peace of mind.
If you need to lift the mower to access the deck, use a dedicated mower lift or heavy-duty jack stands. Never rely on a hydraulic jack alone, and never tip the mower on its side in a way that allows oil to flow into the carburetor or muffler.
Wear protective gear, including gloves and eye protection. When sharpening blades, use a bench grinder or a file with caution, and always balance the blade afterward to prevent damaging the mower’s internal components.
Frequently Asked Questions (FAQ)
Why does my John Deere LA135 lose power on hills?
This is usually caused by a slipping drive belt or a weakening hydrostatic transmission. Check the belt tension first. If the belt is tight, the transmission oil may be old or the internal center section may be worn, requiring a transaxle service.
How do I fix the engine surging on my LA135?
Engine surging is typically a sign of a partially clogged pilot jet in the carburetor. Use a high-quality fuel system cleaner or remove the carburetor to clean the internal jets with a fine wire and aerosol carb cleaner.
What is the correct tire pressure for the John Deere LA135?
Generally, the front tires should be set to 14 PSI and the rear tires to 10 PSI. Correct tire pressure is vital for maintaining a level deck and ensuring proper traction on slopes.
Why won’t my mower blades engage?
Check the deck belt to see if it has jumped off a pulley or snapped. If the belt is fine, inspect the manual engagement cable for breaks or excessive slack. Ensure the idler arm is moving freely and not rusted in place.
How often should I change the oil in my LA135?
John Deere recommends changing the oil and filter every 50 hours of operation or at least once per year (usually at the start of the spring season). Regular oil changes are the best defense against engine wear.
Conclusion
Managing john deere la135 problems doesn’t have to be a daunting task for the DIY gardener. By understanding the relationship between the fuel system, the transmission, and the mower deck, you can keep your 100 Series tractor running like new for years to come.
Remember that consistency is the key to longevity. A mower that is kept clean, lubricated, and fed with fresh fuel will always outperform one that is neglected. Take the time this weekend to inspect your belts, check your oil, and sharpen those blades.
Your lawn is a reflection of your hard work and care. With a well-maintained John Deere LA135, you’ll spend less time troubleshooting in the garage and more time enjoying the beauty of a perfectly groomed landscape. Happy mowing!
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