When to Replace Lawn Mower Belt (Drive & Deck Belts)

when to replace lawnmower beltThe lawnmower belt(s) is the main component that helps drive the power from the engine to drive the propeller which cuts the grass.

Over time, general wear and tear will occur and the belt(s) will eventually wear out and potentially break or not be able to cut your grass as efficiently.

But when is the best time to replace it? We will also review how long they last and ways to make the belt last longer whether it be on a push, self-propelled or riding lawn mower.

When to Replace Lawn Mower Belt?

There are two different types of belts; a drive and deck belt. The deck belt is the main belt which helps drive the propeller to cut the grass. The drive belt is what helps move the mower on its own (self propelled or riding mowers).

If you have a push lawnmower (electric or petrol) this will only have a deck belt. The belt should last the lifetime of a typical lawn mower (8-10 years, if used in ideal conditions and properly maintained). However if in the situation the deck belt needs to be replaced you will find out the propeller doesn’t run and not cut the grass where this is the most obvious symptom (other symptoms are explained later).

If you have a self-propelled or riding mower, you will find an additional belt which is the drive belt. As it states in the name, this helps drive the wheels of the mower to move and will help drive the other components for the deck belt. These belts last between 3-4 years (again depends on the amount of use of the lawnmower) and should be replaced within this time period, but of course if the mower is still running as it should, the replacement will be put off but there are various signs and symptoms to indicate if the belt should be replaced which is explained in the next section.

How to tell if a mower belt is too worn?

There are easy tell-tale signs which show a worn mower belt, but how do you tell the difference between a worn (still ok to use for a fair few sessions) or a very worn belt (will most likely break in the next one or two sessions).

The best way to check is to visually inspect the belt and the upcoming signs are of belts which need replacing.

One obvious sign is whether the belt is shiny and completely flat with little to no ridges or bumps (depending on belt design) on the surface which fits into the grooves of the pulley system. Then this is the obvious sign of a worn belt that needs replacing.

Other signs are cracks in the actual belt itself. If you bend the belt the other way from its natural position and it splits open then the belt has been cracked and it won’t be long until it snaps.

If you find the belt quite slack between each pulley, this is also a sign of old age or wear and tear. This will not efficiently run the mower and will be more prone to slipping when mower is on. Don’t get confused if you have a feature to un-tension the belt on the mower which is normal depending on the design of your mower.

If it is particularly difficult to access the belt or you want a quick way to notice the belt is too worn, keep particular attention to your next mowing session. Some signs may include:

General signs:

  • Squealing or squeaking noises while the mower is on

Deck belt

  • Patchy grass cutting (blade stops spinning and therefore won’t cut)

Drive belt

  • Mower stops/stutters at times (as it has lost traction to drive the wheels)
  • Excessive vibration through the mower

when to replace lawnmower drive and deck belt

When to replace self-propelled lawn mower belt

One key design of the self-propelled lawn mower is that it helps move the mower along which prevents you from having to push the mower, only requiring you to steer it in the direction of where you want to cut your grass. If you suddenly feel that you need to exert more force into pushing the mower or if the drive is slower than usual it is time to replace the drive belt. The last thing you want is the belt to snap as this can cause problems elsewhere if it gets caught or hits other components.

When to replace riding lawn mower belt

Similarly to a self-propelled lawn mower, you will need to replace the drive belt from time to time, you will find similar symptoms to the self propelled lawn mower where the mower may not drive very well, the belt may slip and mower may feel it is stuttering while driving.

Why does my lawn mower belt keep breaking?

If you have recently broken your mower belt or just replaced your mower belt and the belt has broken in no time, there are reasons why this has happened.

One common problem is excessive cut grass clippings on the deck. These clippings can get caught in between the pulleys which the belts are directly driving. This will cause unwanted additional tension to belts and may cause stretching to the belt which will loosen and then more grass clippings could get caught and would eventually snap the belt.

Another problem could be an oil leak within the engine, this will simply destroy the belt. If you have recently replaced a belt and it has broken with little use of the mower, you should check for oil leaks.

Broken or faulty pulleys can also cause broken belts. The pulley is meant to spin freely as the belt gets pulled around it. If the pulley is not spinning freely, uneven or excessive friction will occur on the belt and consequently wear it out quicker. If the pulley doesn’t look broken it is worth checking the bearings as these may be worn and may need replacing.

If you have recently replaced your belts, it is important to tension the belt correctly according to your owner’s manual. If it has been over-tensioned, this will cause excessive strain on the belt when in use and will break quicker than usual. Misalignment of the belt to the sheave (groove(s) of the pulley) can also cause excessive wear, so make sure the belt grooves are aligned properly within the pulley, an easy way to check is if you spin one pulley the other pulley that the belt is wrapped around will move at the same time and frequency.

Checking the type of belt used in your mower is important especially if you are going away from what is stated in the owner’s manual. Factors such as the material, type of the belt and lengths are important and vital to ensure the belt lasts the intended lifetime they were made for. If you have purchased a belt that is not recommended within your owner manual but the design and lengths of the belt are correct the material is likely not to be the same as the original and most probably won’t be able to take the strain of the mower over its intended life.

It is worth noting some mowers only allow you to use the OEM (original equipment manufacturer) components, so no matter what belt you buy even if you match all the specifications of the OEM belt it may still not last as long as intended. However if in the case you can use other belts, use a belt which is made from Kevlar (often used in bulletproof vests), this is far more long lasting than the regular rubber reinforced with polyester cord belts. Although this is a more expensive option it might be worth using if it is particularly hard to change the belts depending on your mowers design.

Also Read: How to Test A Lawn Mower Fuel Pump

How to keep lawn mower belt running for longer?

If you want to keep the replacement of the belts to a minimum these common procedures and guidance will keep the belt running for longer:

  • Remove grass clippings at the end of every session (check the deck and in between the pulley belt)
  • Use the mower for no longer than the recommended time, excessive heat will cause unnecessary wear the belt and weaken it over time
  • Check the tension of the belt as often as possible and adjust where necessary as according to your manual
  • Use the mower in the ideal conditions (dry and not completely over grown grass), if you are using it in conditions that are not ideal (wet and completely overgrown grass) it will wear the belt far quicker, if you do have very overgrown grass, trim it down first and complete the lawn in 2 sessions

The advice above is generic and covers all the mowers but of course refer to your owner’s manual and the recommendations of maintaining the mower as there may be extra/special features which may not be on regular mower that may need special attention which may affect the belts if not properly maintained.

Related Questions.

Do you have to remove mower deck to replace belt?

This will depend on the type of mower you have. On a riding mower the belt should be accessible at the deck when it has been lowered to its lowest position or if you can lift the mower to access underneath the deck. However, if you have a self-propelled or push mower, this may be more difficult as this is often covered and protected by casing, so yes you may have to remove the deck to replace the belt. A drive belt is more difficult to replace and you are more likely to need to remove the mower deck on older models. Newer models may be designed so that the drive and deck belts are accessible once the cutting deck has been lowered into the lowest position. Again with any maintenance ,check your owner’s manual.

How many belts does a riding lawn mower have?

Some texts state that a riding lawn mower will have 2 belts (drive and deck belt) whereas some refer to 3 belts (Power Take-off Belt (PTO) or Power clutch belt, Arbor belt and Drive belt). The PTO and Arbor belt is often referred to as the ‘deck belt’ as these are found within the deck which help drives the cutting propellers. These are different belts which is found in the same area but differ in lengths and use in the actual lawn mower. It is important to check your owner’s manual to ensure you differentiate between the two otherwise the mower won’t run as it should.

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