Lawn Mower Clutch Stuck? Here’s How to Troubleshoot
Lawn mower clutch stuck is a common problem. It can become a real headache and halt your lawn-mowing endeavors. Most mower owners have faced this at least once no matter what type of mower they have.
It can happen because of multiple reasons. This problem usually happens because of belt issues, corrosion, and a worn-out clutch cable among others.
How Does a Lawn Mower Clutch Work?
The clutch in a lawn mower allows the power of the engine to transfer to rotating the blades. It controls the engagement and disengagement of the cutting blades.
A lever is attached to the clutch, the handle, or the pedal near the bottom to operate with your feet. This lever is what changes what position the clutch is in.
On the opposite side of the clutch, there are shoes or pads attached to the pully. When the clutch lever is used it tightens or loosens the cable or linkage to engage the clutch or disengage it.
When the clutch is engaged the engine’s power is transmitted to the clutch plate that drives the pads. The pads start to rotate causing the connected blades to rotate rapidly as well.
Lawn Mower Clutch Stuck: Causes and Remedy
It’s not uncommon for a lawn mower clutch to get stuck. The type doesn’t matter. Be it electric, riding, or a push mower the clutch can get stuck for various reasons.
It is a good idea to understand the reasons behind a lawn mower clutch stuck and how to get it loose so your lawn care doesn’t come to a halt.
These are the most common reasons behind lawn mower clutch getting stuck:
1. Drive Belt Issues
The most prevalent cause behind the clutch getting stuck is problems with the belt. A loose or misaligned belt doesn’t provide enough tension so that the clutch can actively engage.
If the belt slacks it won’t be able to slip onto the clutch and it will get stuck. Also, a cracked belt doesn’t hold the pully with enough power either.
Solution:
The first thing is to determine what the condition of the belt is. Check for fraying or cracking and the tension of the belt by stretching it out with your hands.
If the belt is in good condition it will need to be tightened with fasteners. If it can’t hold the tension you will need to replace it.
Make sure that you are buying the right size belt for the clutch. Here’s how to change the belt:
- Drain any leftover fuel and remove the spark plug.
- Turn the mower on its side and take off the front body shroud and the metal shroud underneath the mower to get the old belt out.
- Put the belt around the pully feed it through the hole to the front and attach it to the pully wheel.
- Tighten the bolts and cover up the housing with the shrouds.
2. Corrosion
Rust and corrosion buildup is a big hindrance to the proper functioning of the clutch. The mower parts can start to catch corrosion if they are stored outside or not used very often.
Corrosion heavily weakens metal parts of the clutch so it loses its flexibility. An engaged clutch gets stuck on coarse parts of the mower.
Solution:
The best solution is to prevent corrosion. You should always properly lubricate the moving parts where corrosion is most likely to take hold.
Store the mower inside a shed during the winter so it doesn’t have any moisture build over this period. Thoroughly clean it and apply lubrication when you take it out after it’s been sitting for a while.
In cases of particularly stubborn rust, rub the parts with a rubber mallet. It can easily dislodge the sitting rust.
3. Broken Clutch Spring
The clutch deck has a spring that deactivates the clutch. This is a big issue for riding mowers. These don’t have much of a clutch on them.
The drive belt is allowed to slip when the pedal is pressed. When you release the pedal a tensioner pully takes up the slack in the belt and applies the necessary friction.
If the clutch pedal is stuck then the return spring is either disconnected or not functioning as it should.
Solution:
There are multiple springs in the clutch. First, you need to identify the clutch spring.
Here is a typical lawn mower clutch deck:
Most mower decks will be similar to this one. Identify the clutch spring and see if it is connected. Reconnect the spring if it is out of place.
If the spring is not in good condition or is broken then you will have to replace it. The procedure is very easy. After disconnecting the old spring you just have to connect both ends of the new one to the clutch.
You can watch this video to get a better idea of how to replace the spring.
4. Issues with the Hydrostatic Transmission
If your lawn mower has hydrostatic transmission, then this might be a very good explanation for a stuck clutch.
Contaminated hydraulic fluid or even low levels can disturb the transmission. If the fluid is leaking it reduces the pressure that the clutch needs to engage.
It relies on a pump or motor to operate. If the motor isn’t functioning properly it will reduce the power transfer and overheat the system.
Solution:
Check the hydraulic lines and clear blockages so the fluid can properly pass through. Check the fluid level and refill it if it is low.
If the fluid is contaminated drain and replace it. If the line feels damp or has oily spots you may have to patch up leaks and clean the area.
Clean the cooling fins so the system can dissipate heat. Check for proper airflow and keep the clutch dry. If the fluid is leaking onto the clutch it will start to develop corrosion.
How to Adjust a Lawn Mower Clutch?
If you are having issues like lawn mower clutch stuck a very quick solution is to adjust the clutch.
The clutch sometimes fails to engage after it’s been warmed up. But later when you try to turn it back on it has a hard time reengaging. Dropping the RPM of the engine will fix it but it’s not good for the engine.
When a clutch has worn out so much that the current air gap is too large to complete the engagement, the brake shim can be removed to restore the gap.
Usual air gaps in lawn mower clutch:
| Clutch Manufacturer | Engine Horse Power | Air Gap |
| Ogura | Under 25HP | 0.013”-0.015” |
| Ogura | Over 25HP | 0.015” – 0.022” |
| Warner | _ | 0.020” |
Here’s how to adjust your lawn mower clutch:
- Number 1 is the slot you use to check the clearance and 2 is the nut that adjusts it.
- Use a feeler gauge to check what the current levels are one by one. Use a quarter-inch ratchet to tighten the nut.
- When you sinch one side down there will be quite a bit of gap on the other sides. After bringing down the other two sides the first one might get a little tighter. Use the gauge to see how tight it is and loosen it accordingly.
- Keep making the clearance smaller until you hit the right amount of air gap for the clutch on all three sides.
- You want the tightest amount of clearance without the pully touching the magnetic pickup inside. Get it to a point where it spins but doesn’t make any screeching noise.
Frequently Asked Questions (FAQs):
How do you know if the lawn mower clutch is going out?
Before turning the engine on, engage and disengage the lever. If the pulley slows down, then the clutch has fused with the plates and won’t be in working order for very long.
Can you repair a PTO clutch?
Yes, you can fix a PTO clutch but it’s a relatively lengthy and complicated process.
What does the clutch cable do?
It helps put the lawnmower into gear, controls transmission on riding mowers, and offers the user direct control over the cutting blades.
