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Briggs & Stratton Lawnmower Drive & Cutting Problems: Troubleshooting with fixes

Briggs & Stratton is a renowned lawnmower manufacturer. Many homeowners who use a Briggs & Stratton lawnmower may encounter issues such as uneven cutting, poor driving, etc. While some problems may be easy to fix, others require troubleshooting various components in the lawnmower.

Briggs & Stratton Lawnmower Cutting & Drive Problems:

If your Briggs & Stratton lawnmower’s cutting performance has declined, inspect the blade for uneven wear, loose mounting, and blunt edges. Dislodge any grass clippings and debris stuck between the spindle and the blade. Inspect the drive belt if the lawnmower doesn’t move forward or drives jerky. For a self-propelled lawnmower, check the wheels in addition to the drive belt and pulley to see if they spin freely.

By following these steps, you can pinpoint the reason behind the problem and see if it can be fixed by yourself or requires professional assistance.

Briggs & Stratton Riding Lawnmowers: Troubleshooting Cutting Problems

If your lawnmower cuts in non-uniform patches, cuts in lines that are not straight, or doesn’t cut at all, you should read the following sections:

1. Lawnmower Is Not Cutting Straight.

Your mower is not cutting grass straight for these reasons: 

1. Unequal Tire Pressure: 

Unequal tire pressure can be a reason for your Briggs & Stratton Lawnmower not cutting straight. Check the tire pressure to see if there is a difference between the wheels.

One of the likely causes of non-uniform grass patches is low tire pressure. Due to low tire pressure, the deck will not be balanced on all sides and will sit lower on one side. 

I recommend using a tire pressure gauge. Or, if it’s visually noticeable, you can determine which tires need to be filled. Make sure the pressure is filled as per the recommended sidewall rating.

If the problem still exists, proceed to the next step.

2. Dull or Worn Blades: 

Long-term exposure to dirt causes the blade edges to wear out and become blunt. In this case, you need to remove and sharpen the blades. Several methods to sharpen lawnmower blades are explained in more detail in different articles. Do not forget to balance the blade after sharpening.

If the blade is seriously damaged, I recommend replacing it.

If sharpening doesn’t resolve the problem, go on to the next step.

3. Unbalanced blades: 

An unbalanced blade weighs more on one side than the other. This could happen due to uneven wear or sharpening, which removes more metal from one side than the other. If it is unbalanced, it can vibrate while rotating.

These blade vibrations may harm the spindle bearings. Remove the blade and check the balance using a blade balancer. If you don’t have one, you can hang your blade on a nail in the wall.

If the blade balance is off slightly, you can use a grinder or file to remove some metal from the heavier side. If the imbalance is significant, I recommend replacing it.

4. Defective Spindle Bearings:

If you have a defective spindle or a damaged bearing, your blade may vibrate when spinning under the deck, producing an uneven cut and a screeching noise.

To determine if the blades are out of balance, put some pressure on one end and rock it back and forth while listening for a knocking sound. The spindle bearing is likely damaged when you feel some play or hear a sound.

In this case, the blade and its spindle bearing need to be removed, and the spindle needs to be replaced. This is a more complex job. Ask a professional for help if you do not trust yourself with this. 

2. Lawnmower Cuts Uneven Grass Patterns.

Some of the causes of irregular grass patterns are 

  • Dull Blades: Check for blunt edges by visually inspecting the blades. If they seem blunt, sharpen them or replace the blade if they’re too worn out or damaged. 
  • Worn Deck Belt: The cutting could be uneven if the deck belts are worn out or really loose. This can cause the mower to vibrate as it moves. You should inspect the belts underneath the deck and tighten them if needed. If they appear worn out, replace them. 
  • Inconsistent Speeds: Uneven grass patterns could also result from varying mower speeds. Maintain a steady, uniform pace as you operate the lawnmower. Try to avoid rushing or suddenly slowing down when mowing.
  • Deck Height: Adjust the mowing deck’s height by raising or lowering it. To adjust the height of the deck, use a level gauge to measure and the adjustment screws to set. Ensure the deck is evenly balanced on all sides and the cutting height is set according to the manufacturer’s instructions.
  • High grass: If you mow tall grass and notice that your lawnmower has problems with its engine power, set the mowing deck to a higher height. And trim the area in two or more steps. When the engine has problems keeping the blade spinning at the correct speed, it will cut the grass not efficiently and result in uneven grass patterns.

3. Lawnmower Doesn’t Cut at All?

If the lawnmower fails to cut the grass at all, you need to inspect the following components: 

1. Examine the Blade Lever: 

Ensure the blade engagement lever is pressed correctly. The blade engagement lever pulls the blade clutch cable, which engages the blade with the crankshaft. The blades won’t rotate and cut the grass if the lever isn’t pressed and the engine is running.

Dirt or clipped grass may occasionally clog the clutch cable. To fix the problem, disassemble the lever and thoroughly scrub the mower deck’s underside to remove the grass.

2. Worn-Out Blade Belt: 

A worn-out belt may prevent the blades from cutting grass if it cannot grip the drive pulley on the spindle. Furthermore, this could result in jerks or vibrations that result in uneven cuts. To prevent this, you should routinely inspect the mower deck’s components, including the blade belt and its pulley. Tighten the belt if needed, and replace if it looks worn out.

3. Locked-Up Spindle Assembly: 

The mandrel assembly, or the spindle, spins the blade to cut the grass. The blade won’t move if the mandrel jams up due to wear or excessive dirt buildup. The mower deck may vibrate and, as a result, cut non-uniformly due to a damaged mandrel. 

The spindles should undergo routine inspection to determine when to replace them. I recommend asking a professional to disassemble and replace the mandrel assembly is often a good idea when you feel uncomfortable doing it yourself.

Briggs & Stratton Riding Lawnmowers: Troubleshooting Drive Problems

Problems with the drive belt or gearbox transmission are the most frequent causes of drive-related problems in riding lawnmowers. The most commonly occurring issues with riding lawnmowers are listed below.

1. Lawnmower Doesn’t Move Forward.

Your riding lawnmower may not be moving forward due to the following reasons: 

1. Examine the Drive Belt: 

The drive belt differs from the blade belt as it drives the axle pulley, which rotates the lawnmower’s wheels and causes it to move. The drive belt might wear out and become loose over time.

The power transfer to the wheels is therefore impacted. The problem can be fixed by tightening the belt or replacing it when it looks worn out. 

If the issue remains, go to the next step.

2. Inspect the Transmission:

Some lawnmowers have a hydrostatic transmission. This works through a system of hydraulic pumps and oil to transfer power from the engine to the wheels. If your lawnmower has this transmission type, check and replenish the oil lever after regular intervals.

If your hydrostatic transmission does not work well, I normally recommend to ask a professional for help. These transmissions can be quite complex and can be challenging to diagnose.

A mower with a traditional gearbox transmission could be inspected for mechanical issues, loose bearings, lack of lubrication, etc. Since this repair requires removing and disassembling the gears, I also recommend asking a professional for help.

2. Lawnmower vibrate excessively?

 Your lawnmower could be vibrating for the following reasons:

1. Unbalanced Blades: 

An unbalanced blade is one of the more common reasons for vibrations. The unbalance can come from hitting a rock or other object. To inspect the blade balance, it is best to remove it and hand it on a nail.

Alternatively, you can use a blade balancer tool to perform this job. At higher RPMs, the imbalance in the blades could cause vibrations that can damage the spindle and the bearings of your machine.

If the imbalance is slight, you can try to remove some metal from the heavier side. For a more significant imbalance, I recommend replacing it. 

While checking the blade, inspect the spindle and mandrel assembly and see if there’s any play. This could also be a source of vibrations while the blade may be perfectly balanced.

2. Loose Engine Mount: 

The lawnmower could vibrate excessively if the engine’s mounting bolts are not securely fastened after a repair. Sometimes they can also loosen themselves over time. Check that there are no loose or missing bolts. Tighten them if needed, and see if this solves the issue.

3. Crankshaft damage: 

If your lawnmower engine is old (over five years) and has been overheated or overrevved often, crankshaft damage can cause a vibration problem. When an engine is overheated and not lubricated correctly, thermal expansion can cause the piston to get very tight in the cylinder walls.

This exerts an additional load on the crankshaft, which could get bent and produce excessive vibrations in addition to a shutdown. However, this is a much more severe case of an engine seizure. Since it’s difficult and costly to fix, it is usually better to replace the engine.

3. Lawnmower has a Loose Steering?

Maneuvering and controlling your lawnmower is challenging if the steering control is loose. It indicates a play in the steering assembly, which can be fixed by inspecting the bushes and tie rod ends.

  • Disassembly: To fix this, you first need to remove the steering wheel by unscrewing and securing the nut. Remove the adaptor, the top hatch, and other components to make the shaft accessible.
  • Bearing/Bushing Replacement: Inspect the bushings holding the shaft’s mounting bolts. It could lead to a jerky experience while driving the mower if they seem worn out or fatigued. While checking the bushings, check the shaft bearings to see if they’re out of lubricant. Worn-out bearings could also lead to a play in the assembly, leading to loose steering.
  • Loose Connections: Check for looseness in the steering linkage, tire rods, and steering wheel. Tighten any loose connections if you can. Consult an expert if disassembly is required for these repairs. Make sure to lubricate every component thoroughly.

4. Lawnmower has a flat tire?

Due to a flat tire, your riding lawnmower may become inoperable until fixed. Here’s how it can be fixed.

  • Locate the Puncture: Take off the punctured tire and pump air into it. Use water with a lot of soap on top of the tire to find the puncture location. This works well for bigger holes. If this does not work, you can place the tire in a water-filled tub and check for air bubbles. The point where the air bubbles are escaping is the site of the puncture.
  • Fix the Puncture: Use a puncture repair kit to fix the damaged tire. After applying the patch and pressure, leave the tire in this position for roughly 20 minutes.
  • Pump the Tire Up: Pump the tire up to the recommended minimum pressure after putting on the patch.

5. Lawnmower is leaking oil?

A broken engine gasket is most likely to be blamed if a lawnmower leaks oil. Occasionally, oil may leak out due to a damaged drain plug.

– Worn Gaskets:

The seals between the engine block and the cylinder head are called gaskets. The piston assembly is in the engine block, and the valves and spark plugs are in the cylinder head. Gaskets are used to prevent engine oil from entering the cylinder head.

Due to their rapid thermal expansion and contraction, these gaskets eventually become worn out. This can be detected by oil spills around the engine’s cylinder head.

Gaskets are generally inexpensive, but replacing them can be challenging and take time. Ask a professional for help if needed.

– Drain Plug:

A damaged drain plug under the oil tank is another reason for an oil leak. Small oil puddles appear under the oil tank, indicating that the source of the leakage is possibly the drain plug.

It is crucial that your lawnmower should never be tipped over so the air filter faces down. Oil spills out of the air filter as a result of this flooding. Additionally, ensure the oil tank is not overfilled. I recommend using a maximum level of around 3/4th of the top level. Oil spills from overfilled tanks might give the impression of a leak.

Briggs & Stratton Self-Propelled Lawnmowers: Troubleshooting Drive Problems

Self-propelled lawnmowers are efficient for smaller yards to tidy them up and present a clean, neat look. However, a self-propelled lawnmower may need help with the following troubleshooting problems. 

1. Lawnmower Doesn’t Go Forward.

If a self-propelled lawnmower starts but doesn’t move forward, there can be multiple issues, particularly with the drive mechanism. Here’s how you can troubleshoot them step-by-step:

  • Step 1. Engage the Drive Control: The lawnmower won’t move forward if the drive control lever or button isn’t engaged or placed correctly. Check if the issue has been fixed after pushing the lever. Proceed to the next instruction if not.
  • Step 2. Driver Belts: A drive belt that is loose or has worn-out teeth won’t transfer enough power to the pulley, and the mower may not move forward. Look for any signs of wear or damage on the belt. You should purchase a new belt if your old one is worn out or damaged. 
  • Step 3. Inspect the Wheels: Check the wheels for any dirt that may have become wedged between the wheels and axle. The wheels and axle should be cleaned of all debris and grass clippings. Determine if the wheels can freely spin.

2. Is the Lawnmower Throttle Not Working?

By moving the throttle cable, the throttle lever controls the engine speed. If the lever doesn’t perform the desired action, take the following actions:

a. Throttle Cable:

The throttle cable controls the butterfly valve, which regulates the air-fuel rate of the engine for combustion. If the cable gets stuck, the throttle function becomes ineffective.

Check to see whether the cable can be adjusted manually. Try applying some oil to see if that fixes the cable. If nothing works, you may need to replace the cable. This will fix the issue in most cases.

b. Carburetor: 

The throttle cable sometimes functions perfectly, but the engine speed doesn’t seem to change even when the throttle is used. This suggests that the carburetor is the source of the problem.

Clear the carburetor jets of any residual gasoline to see if the issue has been fixed. Use a carburetor cleaner to remove any accumulated grime. After disassembling the carburetor, use a carb cleaning spray to clean the float bowl and the bowl nut. 

Check the throttle lever once more to determine if the engine speed has changed after cleaning the carburetor and reattaching it to the lawnmower. The problem should certainly be fixed now. Consult a professional to perform engine troubleshooting in case the problem persists. 

Drive & Cutting Troubleshooting table

1. Lawnmower Cutting Problems

S#
Problem
Causes
Fixes
1
Lawnmower doesn’t cut straight
a. Dull blades
b. Tilted mowing deck
a. Sharpen the blades using a grinder or a bench file.
b. Using a level, ensure the deck is perfectly horizontal.
2
Lawnmower cuts uneven grass
a. Blade vibrations
b. Faulty spindle assembly
a. Ensure the blade isn’t loose.
b. The blade should be balanced at its center. If not, it should be replaced. c. The spindle bearing should be replaced if it is faulty.
3
Lawnmower doesn’t cut at all
a. Disengaged blades
b. Debris/Grass clippings
c. Worn-out belt
a. Use the blade engagement lever.
b. Clean the spindle from debris and grass clippings.
c. Replace/adjust the blade belt as needed.

2. Lawnmower Drive Problems

S#ProblemCausesFixes
Riding Lawnmowers
1Lawnmower doesn’t move forwarda. Transmission disengaged
b. Faulty drive belt
c. No hydraulic fluid
a. Use the transaxle lever to engage the drive.
b. Adjust/replace the drive belt as needed.
c. Replenish transmission fluid.
2The lawnmower has a loose steeringa. Loose tie rod ends
b. Damaged steering bushing
a. Tighten and lubricate tie rod ends.
b. Inspect and replace the bushing at the end of the steering shaft.
3Lawnmower vibrates excessivelya. Blade imbalance/wobbling around the center
b. Damaged spindle bearing
c. Missing engine mounts
a. Tighten and adjust the blade to balance about its center.
b. Replace the faulty spindle bearing.
c. Tighten the engine’s mounting by adding fasteners.
4The lawnmower has a flat tirea. Low air pressure
b. Puncture by a sharp object
a. Purchase a puncture repair kit.
b. Apply the puncture seal and inflate the tire again.
Self-Propelled Lawnmowers
1Lawnmower doesn’t move forwarda. Loose control cable
b. Worn-out drive belt
c. Debris locking wheels
a. Tighten the throttle control cable
b. Adjust/replace the belt as necessary.
c. Remove the debris from the wheels.
2The lawnmower throttle not workinga. Defective throttle cable
b. Clogged carburetor
The lawnmower throttle is not working
3The lawnmower pull cord is stucka. Damaged spiral spring
b. Damaged pull cord
Replace the damaged springs/pull cord.

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  1. Leona Davis says:

    This article is too technical and complex for the average homeowner. It feels more like a manual for professional lawnmower repair technicians rather than a helpful guide for DIY maintenance.

    • Web Editor says:

      can remove the blade and check for balance issues. Also, ensure proper tire pressure. If the problem persists, a professional should be consulted for further inspection and repair.

  2. Amelia Grant says:

    Is there a troubleshooting guide for the engine and electrical components of Briggs & Stratton lawnmowers?

    • Web Editor says:

      Hi Amelia, for Briggs & Stratton engine and electrical troubleshooting, I recommend checking the manufacturer’s website for a comprehensive guide. Hope this helps!

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