A properly functioning drive belt is the heart of your John Deere 155 riding mower, connecting the engine’s power to the transmission and allowing your machine to move forward and reverse. Over time, exposure to dirt, debris, heat, and constant friction will inevitably lead to wear and tear, manifesting as cracks, fraying, or even a complete break. Recognizing the signs of a failing drive belt – such as a loss of power, erratic movement, or unusual noises – is crucial for both your mower’s longevity and your operational safety. This comprehensive guide will walk you through the precise steps to safely and efficiently replace the drive belt on your John Deere 155, restoring its performance and getting you back to maintaining your lawn with confidence.
Gathering your tools and ensuring safety
Before you begin any maintenance on your John Deere 155, prioritizing safety is paramount. Working with a heavy piece of machinery like a riding mower requires careful attention to detail to prevent injury. Start by parking your mower on a flat, level surface, engaging the parking brake, and, most importantly, disconnecting the spark plug wire to prevent any accidental engine starts. This simple step eliminates the risk of the engine turning over while you’re working near moving parts. Additionally, wear appropriate personal protective equipment, including sturdy work gloves and safety glasses, to shield yourself from potential hazards.
Having the right tools on hand will streamline the replacement process significantly. Here is a list of essential items you will need:
- Socket set and wrenches (typically metric, but check your manual)
- Pry bar or similar leverage tool
- Floor jack and jack stands (or sturdy blocks)
- Pliers (for springs)
- New John Deere 155 drive belt (always use OEM or equivalent for proper fit)
- Owner’s manual (for belt routing diagrams and specific torque specs)
- Clean rags
- Optional: Penetrating oil for stubborn bolts
For your convenience, here’s a quick reference for common tools:
| Tool | Primary use | Notes |
|---|---|---|
| Socket set | Removing bolts and nuts | Various sizes will be needed |
| Wrenches | Holding nuts, tightening bolts | Open-end or box-end |
| Pry bar | Relieving belt tension, leverage | Medium size, careful application |
| Floor jack & stands | Lifting and securing mower | Crucial for under-mower access |
| Pliers | Spring removal/installation | Needle-nose or stout pliers |
Preparing the mower and removing the deck
With your safety precautions in place and tools at the ready, the next step involves preparing your John Deere 155 for maintenance. After disconnecting the spark plug wire and engaging the parking brake, it’s often easiest to access the drive belt by first removing the mower deck. This provides ample space to work underneath the machine and properly route the new belt.
To remove the mower deck:
- Lower the mower deck to its lowest cutting position using the deck height adjustment lever.
- Locate the pins that secure the lift arms to the mower deck. These are typically on either side of the deck. Remove these pins and detach the lift arms.
- Carefully disconnect the PTO (Power Take-Off) cable or spring that engages the blades. This often involves unhooking a spring or detaching a cotter pin. Refer to your owner’s manual for the exact location and method on your specific 155 model.
- With the lift arms and PTO disengaged, gently slide the entire mower deck out from underneath the tractor. You may need to wiggle it slightly or turn the front wheels to facilitate its removal. Set the deck aside in a safe, clear area.
Once the deck is removed, you will have much better access to the undercarriage where the main drive belt is located. For some models, it might be beneficial to raise the front of the mower slightly with your floor jack and secure it with jack stands, ensuring it is stable before crawling underneath. This enhances visibility and maneuverability, making the subsequent steps considerably easier and safer.
Accessing and replacing the worn drive belt
With the mower deck out of the way and the front end potentially elevated, you can now clearly see the drive belt system. The drive belt typically loops around the engine’s PTO pulley, a series of idler pulleys, and the transmission input pulley. Take a moment to observe the current routing of the old belt. It’s often helpful to take a picture with your phone or sketch a diagram to ensure you install the new belt correctly, especially if a routing diagram isn’t readily available in your manual or under the hood.
To remove the old drive belt:
- Identify the tensioner spring or bolt that applies tension to one of the idler pulleys. You will need to relieve this tension to slacken the belt. A pry bar can be useful here to move the tensioner pulley, but be careful not to bend any components. You might need to unhook a spring using pliers or loosen a bolt that holds the idler pulley in place.
- Once tension is relieved, carefully work the old belt off the various pulleys. Start with the easiest pulleys, usually the engine PTO pulley or one of the idlers, then slowly remove it from the transmission pulley.
- Inspect the pulleys for any damage, wear, or excessive dirt buildup. Clean them thoroughly with a wire brush or rag if necessary. Check bearings for play or roughness – now is an excellent time to address any other potential issues.
To install the new drive belt:
- Begin by routing the new belt according to your diagram or photograph. It’s usually easiest to start by placing the belt around the engine’s PTO pulley and the transmission pulley first, then working it around the idler pulleys.
- Ensure the belt is seated correctly in all pulley grooves. This is critical for proper operation and belt longevity.
- Once the belt is fully routed, reapply tension to the system. If you unhooked a spring, reattach it. If you loosened a bolt for an idler pulley, reposition the pulley to create tension and tighten the bolt. Ensure the belt is snug but not overly tight. It should have a small amount of play, but not enough to slip.
- Double-check the entire belt path to confirm it hasn’t slipped off any pulleys and is correctly aligned.
Reassembly and a crucial test drive
With the new drive belt securely in place and correctly routed, it’s time to reassemble your John Deere 155 and perform a crucial test drive to ensure everything is functioning as expected. This final stage is just as important as the replacement itself, as it confirms your work was done accurately and safely.
Follow these steps for reassembly:
- If you raised the front of the mower, carefully lower it back to the ground using your floor jack, removing the jack stands.
- Slide the mower deck back underneath the tractor. Ensure it is centered and aligned with the lift arms.
- Reconnect the lift arms to the mower deck using the pins you removed earlier. Make sure these pins are secure.
- Reattach the PTO cable or spring to the mower deck. Double-check that it is firmly connected and allows the PTO to engage and disengage freely.
- Reconnect the spark plug wire to the spark plug. This is the final step before starting the engine and should only be done when all other reassembly is complete.
Before you commit to a full mowing session, perform a cautious test drive. Start the engine in a clear, open area. Engage the transmission slowly, testing forward and reverse gears. Listen for any unusual noises, such as squealing, grinding, or thumping, which could indicate improper belt routing or a loose component. Operate the mower at varying speeds and make a few turns to ensure the belt stays seated and the mower responds correctly. If everything feels smooth and responsive, congratulations, you’ve successfully replaced your John Deere 155’s drive belt!
Replacing the drive belt on your John Deere 155 riding mower is a manageable task that can significantly extend the life and performance of your machine. We’ve covered the critical steps, from gathering your essential tools and adhering to strict safety protocols to meticulously removing the old belt and installing its replacement. Remember the importance of thoroughly preparing your mower, carefully observing belt routing, and reassembling all components with precision. Following this guide ensures a correct and lasting repair. Regular inspections of your belts and pulleys are key to proactive maintenance, allowing you to catch wear before it leads to unexpected breakdowns. By taking the time to perform this maintenance yourself, you not only save on repair costs but also gain a deeper understanding of your mower’s mechanics, empowering you to keep your John Deere 155 running smoothly for seasons to come.
Image by: Chandler Cruttenden