Self-Propelled Lawn Mowers Moving Slowly or Not Working (How To Fix)

Is your self propelled lawn mower slow, not moving as usual, requiring pushes, or refusing work? If this happens, it’s likely that the drive is faulty. This is a common problem that self-propelled mowers have to deal with, regardless of the make or model. It is easy to fix. So, grab your tool bag, and let’s figure out exactly where the problem lies.

Why is your self-propelled lawn mower moving slowly? The Short Answer

The drive mechanism of self-propelled lawnmowers transfers energy from the driveshaft to its wheels. A defect in one or more of the mechanisms can cause the mower to lose speed and eventually stop entirely. This could include components like the belt, cable, gears, or wheels.

Diagnose a slow or non-moving self-propelled lawnmower

Now that you know where the problem could lie, you’ll need to take a closer look to pinpoint it. So, let’s check the individual components and see which of these is causing the lawn mower to move slowly or if the self-propel is not working on the mower.

Drive Cable

The drive cable connects to the transmission via the handle drive control lever. The cable can break, but more often it can freeze inside the cable sheath. To inspect the cable’s connection to the transmission, you will need to get to it.

This connection is usually located under the lawnmower. Once you have located the transmission, the cable connection point, make sure to check how much slack is in the cables. If the cable is very loose, the cable sheath and spring attached may have stretched out and need to be replaced. If you give it a tug, you’ll soon find out if it has snapped as the cable will continue pulling from the sheath.

Pull the drive control lever and observe how the transmission is being rotated and moved by the cable. If there isn’t much movement in the transmission, then you will need to replace it with a new cable.

The Drive Belt

Your lawn mower will move slower if the drive belt is stretched out. First, look under your mower to locate the belt. Just remember to tilt the lawn mower over the correct way so that oil doesn’t leak through to the air filters.

Once you have located the belt, pull the drive control lever and check to make sure it tightens. The drive control lever should be pulled to add enough tension to your belt. Finally, tighten the belt against the crankshaft or transmission pulleys. If it’s still loose, then you will need to replace it with a new drive belt.

Drive the wheel

Located inside the wheel of a self-propelled lawn mower, you’ll find a pinion gear hidden away. This tiny gear transfers power from your transmission to the wheel.

Unless you have a mower such as a Honda that uses a metal version, the wheels usually have a gear embedded into them. It’s common for the gears to lose a tooth or two and slow down the drive. This can be felt as a slower and jerkier drive.

So, to check the pinion gear and wheel, you’ll need to pop off the wheel and check inside. If you find that the teeth are worn down or a few are missing, you’ll want to replace the wheel.

Self-Propelled Transmission

The final part of the drive’s mechanism is the transmission. Transmissions can wear down over time, making it difficult to turn. Transmission resistance causes the drive belt’s power and speed to drop.

To check the transmission, lift the propelled wheels from the ground and manually turn the wheel. Make sure the drive control lever isn’t engaged, and give the wheel a spin. Both wheels should be able to turn easily and should turn together. The only resistance you should feel is the transmission’s weight, which should be next to nothing.

Just make sure that the belt isn’t rubbing too much when you spin the wheels and that no weight is on the wheels. If you find the wheels hard to turn, you’ll want to replace the transmission.

How to fix a self-propelled lawn mower that is slow to move

Hopefully, one of these components was the problem that caused your self-propelled mower to move slowly or not work properly. If it was, then let’s take a look at the steps, tools, and parts you’ll need to fix each of the issues.

Safety First

Before carrying out any repairs to your lawn mower, it’s important to keep safety in mind and take the appropriate steps. Keep your eyes and hands protected by wearing gloves. Remember that lawn mowers can burn, have sharp edges, and contain dangerous liquids. To prevent any mishaps, remove the ignition cable and turn your lawnmower over.

Replacing the Drive Belt

The drive belt is going to be the most common problem causing your self-propelled lawn mower to be moving slowly or not propelling at all, so we’ll start here.

Tilt the Mower

To reach the bottom of the lawnmower, tilt the mower in the right direction.

Take the Shroud off

Next, you will need to use your socket wrench and remove the bolt from the mower’s bottom. This will allow you to access the belt.

Take out the Engine Belt Guard

Located next to the driveshaft, you’ll find a belt guard. You’ll need to remove this using your socket wrench set, then set it to one side.

Remove the Transmission Belt Guard

You’ll find another belt guard on the rear of the lawn mower connected to the transmission. This can be removed in the same manner as the engine belt guard.

Take out the Old Belt

Once both guards are removed, you should now be able to lift and slide the belt over the blade.

Install the New Belt

Next, slide the new belt onto the lawnmower the same way as you did the old one. However, this time it is in reverse.

Install the Guard

You can reinstall the transmission and engine guards using your socket wrench. Make sure that you keep the belt in place while installing the guards so that you don’t have to remove them again. I’ve had to remove the guards a few times because the belt had slipped off, so keep an eye on where the belt is when you’re putting on the guards.

Replace the Shroud

The shroud is the last thing you should reinstall. Use your socket wrench for reattaching the shroud onto the lawnmower.

Make sure to test the lawn mower.

Finally, raise the lawnmower and give it a run. If the drive belt has been correctly diagnosed and repaired, your lawnmower should now run as fast or faster than it used to.

Tools & Parts Required to Replace the Drive Belt

  • New Drive Belt
  • Socket wrench set

Replacing your Drive Cable

I’d place the drive cable as the second most common cause of a self-propelled lawn mower moving slowly or the self-propel not working. This is how to replace your cable if it has problems.

Take the cable from the drive lever

First, disconnect the cable from your drive lever. If your mower is newer, the cover that protects the cable connection may be plastic. Use a screwdriver for the removal of the cover and then take the cable out of its mounting place.

Take the Cable Clips out of the Cable.

Next, take the cable out of the clips at the mower. These clips hold the cable in place and prevent it from swaying.

Remove the Transmission Cover

Now you’ll need to remove the transmission cover from the lawn mower. Some mowers have this cover on top, while others have it underneath. If the cover is underneath, tilt the mower. You will need a socket wrench to remove the fixing bolt.

Take the cable from the transmission

You will see the other end, with the cover removed, of the drive cable attached. This cable is usually held on by a small metal clip. This can be removed with a screwdriver, or needlenose pliers. You should be able to take the cable out once the clip has been removed.

Thread New Cable

Next, attach your new drive cable to the lawnmower. Make sure to thread the cable correctly at both ends. You wouldn’t be the first to clip the cable in backward.

Connect the Cable and the Transmission

Attach the cable in the same manner as you removed it. However, this time, do it in reverse. Once you have attached the cable to the transmission, remove the clips and ensure that the cable is securely secured.

Connect the cable to your Drive Lever

Now connect the other end to the drive lever. You will need to attach it in the same way as you removed it. But this time, do it in reverse. Once you’ve attached the cable to the lever using your screwdriver, you can reinstall the covers.

Reclip the cable

Next, attach the clips to the frame to clip the cable onto the lawnmower. When doing so, make sure that you don’t put the cable under stress, as this can affect how the cable works and could create a new problem.

Reinstall the Transmission Protection

Finally, remove the transmission cover and attach it to the mower. That’s it; the drive cable has been successfully replaced. You should notice a significant improvement in the mower’s drive and speed once you have tested it.

Tools & Parts required to replace the drive cable

  • New Drive Cable
  • Needle-Nose Pliers
  • Socket wrench set
  • Screwdriver

Replace your drive wheel

The drive wheels are number three. It is quite common for self-propelled lawnmowers to have slow or no response times. This is especially true if the wheels are made entirely of plastic. So, here are the steps you’ll need to follow to replace your drive wheels successfully.

Take out the Wheel Hub

The first step is to take off the hubs. These are the covers which cover the axles and nuts on the lawnmower. Next, take a screwdriver and remove the hub cover. To make things easier, there is usually a small groove that you can insert the screwdriver into.

The Axel Bolt should be removed

Next, you’re going to remove the axel nut. For this, you can use a socket tool.

Take the Old Wheel Off

The wheel should pull out easily after the nut has been removed. You can dispose of the wheel by taking it off.

Clean Out Wheel Area

With the wheel area exposed, it’s a good opportunity to clean the area. You might find a bit of old broken teeth from the wheels that you’ll need to get rid of. So, spray some WD-40  onto a cloth and clean the area. While you have the WD-40  in hand, give the pinion sprocket a good coating as well.

Install a new wheel

Next, install the new replacement wheels. You can then slide the wheel onto your lawnmower.

Install the Nut, and Replace the Hub

Last, you will need to tighten the axel bolt using your socket wrench. Finally, attach the wheel hub. If you have purchased an aftermarket wheel, you may find that it doesn’t have a hub cover, so you can skip this part.

Tools & Parts Required to Replace the Drive Wheel

  • Drive Wheels Replacement
  • Socket wrench set
  • Flathead Screwdriver
  • Cleaning Cloth
  • WD-40

Replacing the Self Propelled Transmission

Replacing a transmission on a lawn mower isn’t as difficult as it may sound. The transmission comes complete with the axles and pulleys attached, so it’s just a case of pulling off the old one and installing the new one. Let’s take a look at the steps you’ll need to follow.

Tilt the Mower

First, tilt over the lawn mower the correct way so that the oil doesn’t run into the carburetor and air filter.

Remove the Belt Cover

Next, remove the bolts that hold the belt cover on with your socket wrench. This will give access to the belt.

Take off the Belt Guards

Next, use your socket to remove the bolts that are holding the belt guards on the engine/transmission.

Take off the Belt

You should now be able remove the belt after both guards have been removed.

Remove the Drive Cable

Now, it’s on to the drive cable. First, you’ll need to remove the cable from the transmission. I prefer to use a pair if needle-nosepliers to remove the clip that holds down the drive cable. The cable can be removed once the clip is removed.

Remove the Drive Wheels

Next, it’s time to remove both of the drive wheels. Use your socket wrench and a screwdriver to remove the hub of the wheel.

Take out the Pinion Gear, Snap Rings, and Pinion Gear

Once the wheel is removed, you will be able to see the pinion and snap rings. To remove the pin, use a pair snap ring pliers. The pinion gear should then slide off once the pin has been removed.

Remove Adjustment Plate

On the side of the lawn mower, you’ll find the bolts that hold the wheel adjustment plate in place. This plate is connected to the cut-height adjuster. You’ll need to remove the bolt, so the plate becomes free from the mower. You can use a socket wrench to do this.

You can get rid of the old transmission

Finally, that’s everything you need to do to remove the transmission. Take off the adjustment plate and remove the axle. Next, slide the other axle off its mounting point.

Slide in the new transmission

Next, take the new transmission and slide it through the first mounting point as you did with the old one. Next, lift the adjustment plates and slide them onto the other transmission axle.

Fix the Adjustment Plate

Use your socket wrench to reattach the adjustment plates.

Replace the Pinion Gear & Snap Ring

A little grease can be applied to the axle before you replace the pinion. This will give your pinion as long as possible. Once you’ve greased the axle, slide on the pinion gear and reattach the snap ring using your snap ring pliers. Once everything has been installed, give the pinion a spin to make sure everything is running smoothly and that the snap pin is secure. Snap rings can be tricky to get seated correctly, especially if you don’t have the right tool.

Replace the wheels

Next, you’ll need to reinstall the wheels. Now, place the wheels on the axles and tighten the nuts. Finally, if you have hub covers put them on.

Replace the Drive Cable

You are almost done. There are still a few things to do. Next, thread the cable through the transmission and then clip it with your pliers.

Install the Belt

Your belt should be pulled over the blade. Then, thread it onto the pulleys. It should have plenty of slack so it should be quite simple.

Replace the Guards & Shroud

The last tool you’ll need is your socket wrench. The guards are the first thing you’ll need. These will hold the belt in place while your work on other tools. You will need to attach the guards so that the belt stays in the right place.

Check the Mechanism

Before installing the belt cover, it’s a good idea to test how the transmission moves. Give the drive lever an effort; the transmission should rotate, and the belt should be free from slack.

Cover

Once you are satisfied that the transmission is moving properly, you can install the belt cover. You can also test the mower’s performance by taking it around the yard.

Tools & Parts Required for the Replacement of the Drive Transmission

  • New Drive Transmission
  • Socket wrench set
  • Snap Ring Pliers
  • Screwdriver
  • Pliers

How to fix a self-propelled lawn mower that is slow or not working

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