How To Repair A Variable Speed Pulley On A MTD Lawnmower
One of the primary functions of a lawnmower is to spin blades to cut your grass. While this movement is simple, the machinery behind it can be relatively complex. Whether you have a push or riding lawnmower, many different pieces are necessary to make it work. The variable speed pulley is an essential component that allows you to control the movement of the blade. If it breaks, you will experience various problems, including uneven grass.
To repair a variable speed pulley, you will need to remove the cutting deck from the mower. Next, you’ll have to take the pulley out to inspect it and figure out what is wrong. To do this, you’ll have to detach the springs connected to the pulley, as well as the belts. Then, you can remove the fasteners and separate the whole piece.
Since this is a relatively complicated procedure, we’ll break down each step for you. We’ll also discuss why the variable speed pulley is so vital to your lawnmower and how to tell when it needs fixing.
What You’ll Need to Repair a Variable Speed Pulley
- Work gloves
- Safety goggles
- Socket wrench set
- Wooden boards and blocks
Step by Step Guide to Repairing a Variable Speed Pulley
One of the first things you’re going to have to do is remove the cutting deck from your MTD Mower. Since this procedure requires multiple steps, we’ll outline those first.
How to Remove a Cutting Deck
Step One: Park the Mower on a Flat Surface
If possible, try to raise the mower with two dual-wheel jacks. This way, you can get underneath the machinery to work more efficiently. If that isn’t possible, try driving your mower onto wooden blocks. Be sure that the blocks are wide enough so that the tires won’t slip off. Also, wedge a door stopper or something similar to prevent the mower from rocking too much.
Step Two: Place Blocks Underneath the Cutting Deck
The goal here is to reduce the tension on the springs holding the deck in place. So, the blocks will have to support the weight of the deck once you lower it.
Step Three: Lower the Cutting Deck
Make sure to disengage the PTO lever so that the deck will go all the way down.
Step Four: Remove the Belts
There is a drive belt that operates the mower blades. You will have to pull this off. There may also be a secondary belt, depending on how many blades your mower has.
Step Five: Detach the Springs
There are multiple tension springs that connect the cutting deck rod to the rest of the piece. You may have to use pliers to unhook these pieces.
Step Six: Raise the Cutting Deck Arm and Remove the Deck
Before sliding the deck out, you will need to raise the arm. This prevents it from getting in the way and preventing the deck from detaching.
Once this job is complete, you can move onto the steps to remove and repair a variable speed pulley.
How to Remove a Variable Speed Pulley
Step One: Remove the Large Spring
There is a tension spring that connects the variable speed idler arm to the chassis of the lawnmower. You may have to use a starter cord or a spring puller to loosen it enough. Similarly, pliers may work as well.
Step Two: Remove the Small Tension Spring
There is another spring holding the idler pulley in place. You have to take this out to relieve the tension on the belt. Again, pliers may be necessary for this step.
Step Three: Remove the Upper Drive Belt
Once the tension is released, the belt should slide off relatively easily. Check for cracks and other signs of damage. If the belt is frayed or worn, it’s time to replace it. You will have to raise the middle sheave on the variable speed pulley to allow the belt to come off.
Step Four: Loosen and Remove the Pulley
There is a bolt that holds the pulley in place. You will need to use a socket wrench to get it out. Once the bolt is removed, the pulley should simply slide off.
Step Five: Inspect the Pulley
This piece is made up of disks and belts, each of which can crack and break under pressure. Usually, it’s better to replace the pulley with a new one, rather than rebuild the old model. Overall, you want to find any broken components so that you know what to swap. However, if you are having trouble finding specific parts, just replace the whole thing.
Step Six: Reinstall the Pulley
To put the variable speed pulley back on the mower, you can reverse the steps we listed above. Place the pulley on the spindle and secure it with the bolt. Next, wrap the drive belt around both pulleys. Once the belt is secure, you can reattach the small tension spring. Finally, reattach the large tension spring. Again, pliers or some metal cord can make this process easier, since these springs are not very flexible.
Step Seven: Reinstall the Cutting Deck
Put the cutting deck back onto the wooden blocks. Lower the cutting deck arm, and reattach the tension springs. Once that is done, you can replace the belts. Fortunately, an easy way to tell if the cutting deck is secure is to raise it. If it works well, you shouldn’t have any problems.
Step Eight: Test the Mower
Since the variable speed pulley is such an integral part of your lawnmower, you want to be sure that it’s working properly. If you fixed the pulley instead of replacing it, this test is even more crucial since it will tell you if your repairs are good.
Tips and Tricks for Repairing a Variable Speed Pulley
This is a relatively complex job, so here are some ways to make it a little easier.
- Read the Manual First – Most MTD mowers have a similar layout, but you’ll want to familiarize yourself with the engine’s internal workings. This way, you can work faster without having to refer back to the schematic over and over again.
- Have a Helper – Unless you know your mower inside and out, having someone nearby to read instructions and potentially hold a flashlight can make a huge difference. Also, an assistant can make it easier to reattach the tension springs.
- Wear Eye Protection – Since some of these pieces are under high tension, you want to ensure that your eyes are protected from any flying parts. This is also why gloves can come in handy, just in case something pinches your fingers while you work.
How to Tell When Your Variable Speed Pulley Needs Replacing
Since there are so many components that make your lawnmower run, any one of them can potentially cause problems. When it comes to the variable speed pulley, here some classic warning signs that it’s acting up.
- High-Pitched Squealing – The pulley operates at a high rpm, so the belts can make a lot of noise if they are off-balance. However, other elements can make this noise, so check all of your belts when working on the mower.
- Excessive Vibration – As with the squeals, an off-balance pulley will vibrate a lot. One method to tell if the pulley is causing the vibration is to run the mower while looking at it. As long as the cutting deck is removed, it should be safe to run a test.
- Burning Smell and Smoke – In some cases, the belts may be rubbing against the sheaves, causing them to burn. If you notice any strong odors while using your mower, a belt is to blame.
Can I fix my variable speed pulley myself?
If the problem is relatively simple, like a bent sheave, then yes. However, we recommend taking the part to a shop to ensure that there are no other potential issues.
Can I use OEM parts for my MTD Mower?
It can be hard to find pieces for a variable speed pulley online, so you’ll likely have to go to MTD directly. Also, keep in mind that using aftermarket parts may void the warranty.
We are a team of passionate homeowners, home improvement pros, and DIY enthusiasts who enjoy sharing home improvement, housekeeping, decorating, and more with other homeowners! Whether you're looking for a step-by-step guide on fixing an appliance or the cost of installing a fence, we've here to help.
More by Upgraded Home Team