Husqvarna mower belt tension. Husqvarna mower belt tension

How To Tighten Your Riding Lawn Mower’s Deck Belt

The deck belt on your riding lawn mower connects its engine and blades. Tightening this belt is an important aspect of lawn mower maintenance. If you don’t adjust this belt as it loosens over time it will slip and wear out rapidly. Do your blades take more than a second to engage? Do they slip when loaded up with grass? It may be time to adjust your riding lawn mower’s deck belt.

Can you tighten a mower belt?

Your riding lawn mower or lawn tractor‘s deck belt will grow looser over time. And while you cannot shorten this belt, you can tighten the cable pull which engages it, allowing you to run it for many more months before replacing it.

If you didn’t know that a lawnmower belt needs tightening, don’t worry, many lawn mower owners don’t know this. Steve, mechanic, and host of Steve’s Small Engine Saloon on YouTube admits this ignorance extends to some small engine mechanics:

“I know for a fact that there’s a lot of you guys out there that don’t even know that this [adjustment] exists on these mowers because I’ve worked with several small engine mechanics in my life that didn’t even know you could do this either.”

Steve of Steve’s Small Engine Saloon

The problem with not adjusting your lawn mower deck belt is you need to spring for an expensive new belt whenever the old one begins to slip. Adjusting your deck belt’s tightness throughout the season can save you a lot of money.

How do you fix a slipping belt on a riding lawn mower?

Tightening the belt on your lawnmower deck is as simple as pulling the engagement spring tighter. Find where the activation cable connects to the engagement spring: it should be a bracket bolted to the deck. Simply move that bracket away from the spring and toward the cable.

How do you move this bracket? Well on a John Deere riding mower you loosen the 10 mm bolts holding the bracket to the deck. Then you slide it away from the spring and belt. Finally, you torque these bolts back down.

Your riding lawn mower may use a different type of bolt, but chances are that the concept is the same. Obviously, you should only adjust your deck belt with your lawnmower turned off. In addition, you will need your mower deck lever flipped to “disengaged” to have enough slack to adjust your belt.

How tight should a mower deck belt be?

When your tractor is turned off with its deck engaged, grab your deck belt by hand and try to twist it. You shouldn’t be able to twist the belt more than a quarter turn by hand. If you can twist the belt a half turn by hand, you need to tighten it.

Obviously, if your lawn mower is turned off and the deck lever is flipped to “disengaged,” its deck belt will be much looser.

Home and Garden Geek adds that you should be able to loop one or two fingers over the same belt when the tractor is off and the belt is “engaged” and pull it gently away from the pullies. This translates to one or two pounds of force. If you need more than two fingers, your deck belt may be too tight.

Another test you can run is to turn on your mower, rev the throttle up, then flip the deck engagement lever as fast as you can. You should hear your blades reach full speed in a half a second. If you don’t, your belt is too loose.

If you have maxed out your adjustment bracket and your lawn mower deck belt is still loose, than it is probably time to replace the belt with a new one.

Next, learn how to sharpen your lawn mower blades or see how to tighten your lawn mower deck belt in the video below:

Husqvarna Mower Drive Belt Problems | Get the Easy Solution in 10 min

If you have a big lawn then you should buy a Husqvarna mower to mow the lawn smoothly. It is a fabulous invention to cut the grass on a large area. Cutting the grass on your lawn is an easy task when you know the proper use of the lawnmower. You must know the function of every part of the Husqvarna mower if you want a perfect execution.

One of the common problems is the Husqvarna Mower Drive Belt Problem that you have to know how to fix. What do you know about the drive belt? The drive belt is a very crucial part of the mower. The drive belt has an important role in mowing. It determines whether the wheel will move or not.

The drive belt is also known as the blade belt. If something goes wrong with this then your mower will not run. If the belt is damaged your mower will move slowly because the belt slides on the pulley. Sometimes the belt can be loose. Here I will discuss how to adjust the belt tension.

If you understand the Husqvarna drive belt diagram then Husqvarna mower drive belt adjustment will be easy for you. Don’t panic about it. This blog will help you a lot.

Step 1: Park your mower on a plane surface

As always you must put the mower on a smooth, even, and level surface. Make sure the easy access to the underneath of the mower. Stop the mower properly. Use a parking brake to prevent moving. Carefully tilt the side of the mower otherwise the oil can run out from the reservoir. It would be best if you use the lift to raise the mower.

Before starting this process you should run the mower in a well-ventilated zone for a few minutes. If the belt and pulley work for a while then you will be able to move the pulley easily. This easy step will make the Husqvarna drive belt installation easier.

Step 2: Detach the Spark Plug

You may think why should I disconnect the plug? Right? You should disconnect the safety plug for your safety. While working with the belt the engine can start unintentionally. If you remove the spark plug then the engine can not start automatically. On one side of the combustion chamber, the spark plug is found. You must unplug it.

Some people remove the cutting deck while repairing the drive belt. But it has both advantages and disadvantages of removing the cutting deck. But I think lowering the deck will provide you enough scope.

Step 3: Turn the Log Lever.

Log lever is important for engaging and disengaging the Husqvarna mower blades. It can be seen nearby the steering wheel and from the top of the control panel. It arises out of the control panel and continues to the right and so it turns at a 90-degree angle. Grasping the paddle handle twists the log lever.

Step 4: Investigation of Blade Belt.

Then find out the Husqvarna blade belt. I hope you know about the belt and pulley system. You can find it underneath the seat. To investigate this part you must put the mower on a raised floor.

Look at the belt and try to find any crack on it. If there is any crack or chunks you should repair it as soon as possible.

You must inspect the spring arm whether it works properly or not. Does your spring arm go back and forward smoothly? Inspect this thing.

There is a spring in the spring arm. Make sure that the spring is easily expanded by hand. That means the spring should be loose. Also, you need to check the distortion of the belt. Distortion must be adjusted so that the belt can pass over the pulley perfectly. You can loosen the belt whenever you feel that the belt is too tight.

over, you will find a wire that arises from the blade engagement level. It can be enlarged over time, so the belt gets obscure. You should fix this issue as well.

Step 5: Adjustment of Mower or Blade Belt.

All done. Now you may go for the adjustment process. You can find a small bracket. It helps to adjust the cable. You know the blades and deck are disentangled so everything under the deck is in a loose position. You need to tighten the screw over the spring arm.

Now unbolt the washer and screw with the help of an adjustable wrench. Then shift the bracket away. Tighten the bolts and put them in their position back. Make sure there is a proper interval between the bracket and spring. Use a 10 mm wrench for the bracket bolting and unbolting in case of Husqvarna.

When all these things are done put the log lever away and try to engage the blades and mower deck. It would be better if you use grease in the belt before running the mower. over, you should lubricate the pulley also.

Step 6: Double-check the Blades.

Check whether the belt and pulley system is operating well or not. Wearing safety gloves wrap the blades. Make sure that the belt runs over the pulley without slackening or drooping. So easy. All done! Now attach the spark plug and try to begin the Husqvarna engine.

Frequently Asked Question:

1.When should I repair my mower belt?

Nobody can ensure the exact lifetime of your mower belt. There is no fixed amount of time. When the belt needs adjustment you can fix it any time. But it is the best decision to replace the belt every two seasons. After a heavy mowing season, you need to replace the belts to protect the mower from any other serious issue.

2.Does a lawn mower drive belt extent?

Yes, a drive belt can extend. You may hear about the wear and tear effect. Due to this effect, the mower belt will stretch. Unlike the car’s belt, the mower belt is less strong. The belt and blades revolve very fast. Repeated heating and cooling is the main cause of the stretch of the mower belt.

3.Why does my drive belt keep coming off?

When a drive belt becomes loose or damaged the melt may get out. A worn belt can cut while you run the engine. It can be very risky for you. So replace the belt when you notice any crack or damage on the belt.

Bottom Lines

A bad drive belt is a potential cause for your Husqvarna mower to run slow suddenly. You must know the belt adjustment process. I think this article is enough to teach you this process. Follow our guidelines and try this at your home. You don’t need any expert to do this.

Read Our Latest Article:

Husqvarna Mower Drive Belt Problems | Get the Easy Solution in 10 min

If you have a big lawn then you should buy a Husqvarna mower to mow the lawn smoothly. It is a fabulous invention to cut the grass on a large area. Cutting the grass on your lawn is an easy task when you know the proper use of the lawnmower. You must know the function of every part of the Husqvarna mower if you want a perfect execution.

One of the common problems is the Husqvarna Mower Drive Belt Problem that you have to know how to fix. What do you know about the drive belt? The drive belt is a very crucial part of the mower. The drive belt has an important role in mowing. It determines whether the wheel will move or not.

The drive belt is also known as the blade belt. If something goes wrong with this then your mower will not run. If the belt is damaged your mower will move slowly because the belt slides on the pulley. Sometimes the belt can be loose. Here I will discuss how to adjust the belt tension.

If you understand the Husqvarna drive belt diagram then Husqvarna mower drive belt adjustment will be easy for you. Don’t panic about it. This blog will help you a lot.

Step 1: Park your mower on a plane surface

As always you must put the mower on a smooth, even, and level surface. Make sure the easy access to the underneath of the mower. Stop the mower properly. Use a parking brake to prevent moving. Carefully tilt the side of the mower otherwise the oil can run out from the reservoir. It would be best if you use the lift to raise the mower.

Before starting this process you should run the mower in a well-ventilated zone for a few minutes. If the belt and pulley work for a while then you will be able to move the pulley easily. This easy step will make the Husqvarna drive belt installation easier.

Step 2: Detach the Spark Plug

You may think why should I disconnect the plug? Right? You should disconnect the safety plug for your safety. While working with the belt the engine can start unintentionally. If you remove the spark plug then the engine can not start automatically. On one side of the combustion chamber, the spark plug is found. You must unplug it.

Some people remove the cutting deck while repairing the drive belt. But it has both advantages and disadvantages of removing the cutting deck. But I think lowering the deck will provide you enough scope.

Step 3: Turn the Log Lever.

Log lever is important for engaging and disengaging the Husqvarna mower blades. It can be seen nearby the steering wheel and from the top of the control panel. It arises out of the control panel and continues to the right and so it turns at a 90-degree angle. Grasping the paddle handle twists the log lever.

Step 4: Investigation of Blade Belt.

Then find out the Husqvarna blade belt. I hope you know about the belt and pulley system. You can find it underneath the seat. To investigate this part you must put the mower on a raised floor.

Look at the belt and try to find any crack on it. If there is any crack or chunks you should repair it as soon as possible.

You must inspect the spring arm whether it works properly or not. Does your spring arm go back and forward smoothly? Inspect this thing.

There is a spring in the spring arm. Make sure that the spring is easily expanded by hand. That means the spring should be loose. Also, you need to check the distortion of the belt. Distortion must be adjusted so that the belt can pass over the pulley perfectly. You can loosen the belt whenever you feel that the belt is too tight.

over, you will find a wire that arises from the blade engagement level. It can be enlarged over time, so the belt gets obscure. You should fix this issue as well.

Step 5: Adjustment of Mower or Blade Belt.

All done. Now you may go for the adjustment process. You can find a small bracket. It helps to adjust the cable. You know the blades and deck are disentangled so everything under the deck is in a loose position. You need to tighten the screw over the spring arm.

Now unbolt the washer and screw with the help of an adjustable wrench. Then shift the bracket away. Tighten the bolts and put them in their position back. Make sure there is a proper interval between the bracket and spring. Use a 10 mm wrench for the bracket bolting and unbolting in case of Husqvarna.

When all these things are done put the log lever away and try to engage the blades and mower deck. It would be better if you use grease in the belt before running the mower. over, you should lubricate the pulley also.

Step 6: Double-check the Blades.

Check whether the belt and pulley system is operating well or not. Wearing safety gloves wrap the blades. Make sure that the belt runs over the pulley without slackening or drooping. So easy. All done! Now attach the spark plug and try to begin the Husqvarna engine.

Frequently Asked Question:

1.When should I repair my mower belt?

Nobody can ensure the exact lifetime of your mower belt. There is no fixed amount of time. When the belt needs adjustment you can fix it any time. But it is the best decision to replace the belt every two seasons. After a heavy mowing season, you need to replace the belts to protect the mower from any other serious issue.

2.Does a lawn mower drive belt extent?

Yes, a drive belt can extend. You may hear about the wear and tear effect. Due to this effect, the mower belt will stretch. Unlike the car’s belt, the mower belt is less strong. The belt and blades revolve very fast. Repeated heating and cooling is the main cause of the stretch of the mower belt.

3.Why does my drive belt keep coming off?

When a drive belt becomes loose or damaged the melt may get out. A worn belt can cut while you run the engine. It can be very risky for you. So replace the belt when you notice any crack or damage on the belt.

Bottom Lines

A bad drive belt is a potential cause for your Husqvarna mower to run slow suddenly. You must know the belt adjustment process. I think this article is enough to teach you this process. Follow our guidelines and try this at your home. You don’t need any expert to do this.

Read Our Latest Article:

Mower Deck Belt Replacement – Step by step

Replacing belts on your mower is like replacing tires on your car; there are only so many miles in them. Replacing a deck belt can be a challenge, especially if the mower throws the belt and you don’t know the routing, but we’ll get it figured out!

Getting the correct belt is the first important step. Some manufacturers place a label detailing the belt part number and belt routing. Try under the hood or under the footrest; if not, check out “Belt routing.”

Deck types vary. Some are easy to work on, some not so much. It’s important to check over the deck looking for any damaged or loose components, especially if your old belt was damaged and not just worn out. You don’t want to damage the new belt needlessly.

Most mowers won’t require deck removal to fit the belt; others will. So take some time and consider the routing, don’t put extra work on yourself. Take lots of photos; it saves time and head-scratching later.

What’s Involved?

Fitting the new belt means removing some plastic protective covers. And in most cases, it involves wrapping the belt around the pulleys and making sure the belt guide (guide not on all pulleys) is on the outside of the belt. The last pulley to fit is the crank pulley (engine pulley).

Tensioned or Not

A tension-ed belt is a deck drive belt that is always tight on the pulleys. Push-button blade engages type mowers usually run an always tension-ed belt. Replacing it will require manhandling the belt onto the side of the crank pulley, then turning the crank pulley clockwise by hand until the belt slips on.

If your mower has a lever, then you likely have a slack belt which is then tensioned by moving the blade to engage the lever. This type of belt is easier to replace and will take no time at all.

Tensioned – This type of belt is always tight on the pulleys.

Un-Tensioned – This type of belt setup is slack on the pulleys until you engage the blades.

What Deck Type?

Cutting deck setup types vary from side discharge; rear discharge; mulching decks; front decks; cutting, and sweeping.

They may have features such as single-blade; twin-blade; tri-blade; tensioned belt; manual tensioned belt; electromagnetic blade engagement; fan assisted deck; timed overlapping blades, and so on.

The one thing they all have in common – is the deck drive belt. It’s how engine power is transferred into cutting power.

Timed Deck

A timed deck means both your mower blades are set at a fixed angle in relation to each other. The toothed belt maintains the blade position; this allows the blades to overlap.

Some say the overlapping blades give a superior cut; I like the lawn finished with the overlapping twin cut, especially the smaller decks.

This deck type is also referred to as an interference deck. They call it Interference because if the blades go out of time, they’ll smack each other.

Resetting the timing of the blades or replacing the belt is a job that can be done without much difficulty, but it does require removing the deck, tension assembly, and various plastic guards. No special tools are needed.

Rear – Rear discharge is great at collecting grass but doesn’t like long grass so much.

Timed – Timed deck has a toothed belt that can break or slip out of time. Timing the blades allows them to overlap.

Mulching – Some decks will have a flap that closes off the chute when the operator wants to mulch.

Side Discharge – Side discharge is great for tall grass and rough terrain.

Measuring The Belt

A belt will be marked with a type code, length, and part number. Belts are usually measured by their inside length (Li) or outside length (La); if you can find this info on the side of your old belt, great! But usually, it’s worn away.

Some mowers like Husqvarna place a sticker inside the hood with a list of helpful part numbers like belts, filters, plugs, etc.

What Belt Width? – The width and depth of a belt are also very important. A new V belt should fit snugly into a v pulley; the belt should sit just proud of the pulley’s shoulder. A belt that sits further down into the pulley is worn out.

What Belt Length? – If your belt was shredded, then you’ll need your make and model number to order the correct belt. An easy way to measure an old belt – use a string to follow the outside of the belt; now measure the string.

This measurement will be marked on belts by the letters La (outside measurement); alternatively, run the string around the inside of the belt; this measurement is the Li measurement.

A faster way to measure an intact belt is to make a circle of the belt and measure inside to inside, then multiply by 3.14. The result is the Li belt size.

Sizing – Sometimes easier said than done!

Markings – Check under the hood of your mower; you may get lucky with a part number sticker, but be cautious with the Husqvarna labeling; they are often wrong belt part numbers.

Check your old belt for markings; if none, get the tape and some string. These belts are measured in mm.

Pulley – The new belt will be the full width of the pulley. Worn belts usually stretch in length and become narrow in width.

Check Belt Routing

Belt routing, needless to say, is important. On some mowers, it’s possible to put a belt on the backways, which makes the blades turn backward. Not much use for yard work.

If you can, make a diagram or take some pictures of the old belt in place. First, you’ll need to remove both plastic protection pulley covers, one on each side. Some mowers have a handy sticker showing the deck belt routing under the footrest.

That’s great advice, but what if your belt has snapped or derailed? Then you’ll need to check out the links below. Bear in mind, even if you don’t see your maker in the list, check the link out anyway because lots of make share the same decks.

Look at the pulley configuration to see if yours looks similar.

Belt Routing Links

The following link to Google belt routing pictures:

Sticker – Check under the footrest of your mower; some models have a belt routing sticker. This sticker is on a Husqvarna tractor.

Check out the Amazon link below for deck belts.

What Belt Type?

Belts are belts, right? Well, No. The correct belt is crucial. An ill-fitting or wrong-type belt will cause endless trouble. Throwing the belt, vibration, poor cutting, and collecting, and because the belt doesn’t fit correctly, it won’t last very long. I had one customer who fitted a belt that was so tight it broke the end of the crankshaft. Ouch!!

There are many different types of belts; however, when it comes to lawnmowers, they are usually fitted with a standard V-type belt. Other belts used are AA belts, timed belts, and poly V belts.

Sure, you can fit a basic quality belt with a polyester cord, but it’s going to wear out quickly; for durability, you’ll want Kevlar; they cost more but last a lot longer. Some models will only work well with OEM belts, like John Deere and MTD.

I recommend fitting only OEM (Original Equipment Manufacturer). Fitting a belt can be a challenge. Reassembling and discovering what doesn’t work right can be demoralizing.

V Belts

V belts are so-called because of their cross-section shape (wider at the top than the bottom). They are used almost exclusively to drive power from lawn tractor engines to their transmissions. They are also used to drive deck blades. The V belt drives power from one side of the belt only.

They come in different heights/widths and are marked type A, B, C, D. The most common V belts used on mowers are the A and B types, and obviously, they come in a long list of lengths.

Each belt is marked by type and belt length; it may also have a part number. Unfortunately, the markings usually wear off, making the ID process difficult.

AA Hex Belts

The AA belt is a double-sided hexagonal belt; it is mostly used on tractor mower decks to drive the blades. The belts are unique as they have the ability to drive from either side of the belt.

AA Hex Type – This is a double-faced belt; it gives greater flexibility to deck design, as it allows both sides of the belt to drive. It’s used on higher-end tractor decks.

Toothed (Timed) Belts

A mower-toothed or timed belt does two jobs, it transfers power and, at the same time, keeps the mower blades from hitting each other. The toothed belt is a very exact belt in that the teeth of the belt must match that of the mower cogs.

Timed Belt – This type of belt has become more popular in recent years. It’s fitted to mower decks with overlapping blades.

A Type

A Type.This is the most common type of lawn tractor belt; it’s used by many lawn tractor drive systems and most decks too.

B Type

The B-type belt is a heavy-duty A belt; it’s an older well-fed brother.

Check Belt Wear

Belts have a difficult job and can be the cause of various issues. Regular inspection will tell you if your belt is at the end of its life. Things to look for are flat-spotting, glazing, cracking, fraying, and contamination.

As you know, a V belt should sit just proud of the pulley shoulder; if it’s a lot lower than the shoulder of the pulley, it’s worn out.

How Long Do They Last?

The life of a belt is hard to gauge, it really depends on how much grass you’re cutting and how heavy the workload is, but usually, we’re talking years. Typically a belt should be changed after 3-4 years, but we know this doesn’t happen.

A worn or damaged pulley can shorten the life of your belt. An engine or transmission oil leak can destroy the belt, you can try cleaning it, but it causes slip. A derailing belt can get twisted and damaged, and a mower that throws belts regularly probably has a worn or damaged pulley.

But the real killer of belts – tall, heavy grass jams the blades, which causes flat spots on the belt. The flat spot will then cause a lot of vibration, which in turn can throw the belt.

Belt damage is usually caused on the first cut of the season when the grass is heavy. So if your grass is tall and heavy, just take a little off on the first pass and make a second pass with the deck a notch lower. Yes, it’s twice the mowing, but it’s better for your mower and your lawn.

Flat Spot – Flat spotting is usually caused when the blade jams, but the engine pulley keeps running. This has a grinding effect on the belt.

The flat spot will cause excessive vibration in the mowing deck. The fix is – Replace the belt.

Blistering – This can happen when a belt gets old, and the material starts to break down. Your mower won’t cut or collect very well. Better to take care of it now, before it breaks.

Glazing – This belt has a shiny hard surface that is not much good for traction. A belt like this will cause horrible vibration in the mowing deck.

Frayed – Wear and tear, this belt is at the end of its useful life.

Cracked – Natural wear and tear

Check Pulley Wear

A pulley’s job is to route the belt around the chassis of the mower or mowing deck and transfer power from the engine pulley to the driven pulleys. As a rough guide, pulleys usually wear out at the same time as a belt, so best to check them while you have the belt removed.

Tension and idler pulleys should move freely, be quiet when spun, and should feel smooth when turned. If they’re worn, now’s the time to take care of it; when a pulley bearing breaks, it will likely damage the belt.

Spin To Test

You don’t need to remove them to check. Spin them while the belt is off; they should be smooth and quiet. Changing them now is easy.

Bearings

Most pulleys come with the new bearings pressed in place; the exceptions are driven pulleys (Mandrel, engine, or transmission pulleys).

Pulley Types

Pulleys come in all sizes, some metal and some plastic. Tensioners and idlers will have a bearing fitted, and when it wears out, the whole pulley is replaced. Pulleys are usually broken into two main types, flat or V.

A flat pulley is not a driven pulley; it runs on the back of the belt, which isn’t powered (unless it’s on a AA belt).

A V pulley can be driving, driven, tensioner, or idler. A V pulley is described as a driven pulley if it’s connected directly to the output, such as a transmission or a blade Mandrel.

The driving pulley is the engine pulley; it’s the pulley supplying the power. Both the driven and driving pulleys are fixed to shafts using a key and key-way.

A tensioner pulley is part of a moving arm, which, when operated, applies tension to a belt. A tensioner pulley can be a flat or V pulley.

A stationary pulley is usually known as an idler, and its job is to route the belt around the chassis of the mower or mower deck; they can be flat or V-type.

Pulleys – Metal or plastic, V type or flat, driven or idle. So many choices.

V Pulley – This is a V pulley; the driving side of the belt is making contact with the pulley.

Flat Pulley – A flat pulley on a V belt setup is never a driven pulley. Its job is to change the direction of the belt and guide it to the next pulley.

Fitting A Belt

Fitting a cutting blade deck belt that is just worn is the easiest, as you can see the routing of the old belt, and make a diagram or take pictures. Removing the old one also gives you an idea of how challenging fitting the new one will be.

As you know, there are a few variations of deck belt setups; most mowers will have one belt to drive the blades that are either a tension-ed or a un tension-ed belt. The belt can be fitted to both of these types of setups without removing the deck from the mower.

The timed belt setup is a little more involved but not complicated. It has two belts as do so some of the larger John Deere mowers. They can be a challenge as they have many pulleys, and you’ll need to remove the deck.

Pulley Covers

Likely you’ll have already removed the two plastic pulley protection covers, one on each side of the deck. Usually, 2 or 3 screws on each side. They’re not there to protect the pulley. They’re there to protect us from catching body parts in the pulleys.

The latest generation mowers are far more challenging to access as the nice people in the health and safety dept. have been working nights and weekends to find new ways to challenge us.

Removing Belt

Here’s a quick run-through of what we’ll be doing, but it’s all covered in the steps below with pictures. With the covers removed, start by removing the belt from the engine pulley. Often the engine pulley will have a belt guide; its job is to prevent the belt from derailing. Depending on the type of belt guide (if fitted), you may need to remove them first.

As you know, some belts will be tensioned all the time. By tension-ed, I mean the belt is tight around the engine pulley all the time.

The belt tensioner will allow for movement (it’s spring-loaded) so the easiest way to do this is by pulling the belt over the side of the engine pulley and then, with both hands, turning the engine pulley until the belt falls off (Removing the spark plug makes turning the pulley easy).

With the belt off the engine pulley, it’s easy to guide it off the other pulleys. Check your old belt against your new belt, just to be sure.

The un-tensioned belt is simple to fit, and by un-tensioned, I mean the belt is loose around the engine pulley until you engage the blades. The belt can usually be maneuvered around the guides without much trouble.

As with the tension-ed belt, remove the belt from the engine pulley first.

Fitting Belt

Reference your diagram or pictures of routing. Refitting the belt is identical except in reverse order, fitting the engine pulley last by pulling the belt onto the side of the pulley and turning the engine over.

Timed Belt

Most mowers have a simple deck belt setup, like the one covered in this guide is more complex. The demo mower used here has two deck belts driving the mowing deck.

The first one is the main input belt which is powered directly by the engine. This belt is easy to replace, and you don’t need to remove the deck, just some plastic covers.

The second belt is the output belt, and it turns both blades in time. This allows the cutting blades to overlap and catch that annoying tuft of grass you sometimes see in the middle of your cutting strip.

To replace the output belt also known as a toothed belt or timed belt, we need to remove the deck from the mower. It’s not difficult to do, and the whole job shouldn’t take more than an hour.

This guide covers a timed deck belt replacement procedure. Most timed decks will look something similar. It’s more complex than other deck belt setups but not difficult to work on. In this guide, I will: remove the deck; inspect belts; replace the belt; tension the belt; set the timing of the blades.

Tools

No special tools are needed on this mission, but an impact gun would make life a lot easier. When you try to open bolts attached to pulleys, they tend to spin, which is a real pain. Sure, you can wedge it or grab it with grips, but you risk damaging the face of the pulley, and that in turn can damage your new belt. Nooo!

The impact makes small work of pulley bolts, and the better brands have a torque setting built-in which makes reassembly a gift. It’s a super tool to have in the trunk of your car; it makes changing a wheel look NASCAR slick. So treat yourself or drop a few hints before fathers day.

Chute – On this model mower, the chute is fitted through the center of the mower. Not all mowers will have a chute like this. If your mower is side discharge, then you don’t have one.

Remove – As said earlier, you may not need to remove your deck to fit a belt. On this model mower, removing to fit the belt just makes life a little easier.

Pins – Locate the deck arms. Most mowers will have one at each of the four corners. The deck will be fixed to the deck arms with Cotter pins. (Some may have nuts and bolts) Remove the two front pins and the two rear pins.

Slide – The deck will be free to move forward, which allows you to remove the deck drive belt from the engine drive pulley. In some cases, you may have a cable to remove; this depends on the blade engage type.

Push – With all pins removed and belt off, just push the deck sideways and it will pop off the arm bushing mounts. Apply some grease when refitting. Hey, I make that sound easy!

Inspect – Go ahead and turn the deck over to inspect the blades and blade boss (blade attachment). It’s likely that the blades are damaged; if they are, replace them.

Bent – If your blades are bent or worn, now is the time to take care of them. Replacement blades are easy to fit when the deck is off.

Boss – When your blade hits something hard, the blade boss pins are designed to break; this saves damaging more expensive components.

Replace – Check washers and bolts for damage. Blade bolts and washers are specially designed, so only use the original kit.

Remove – Remove plastic protection covers.

Pulley – Remove the drive belt tension assembly.

Key – Remove and store the key and the spacer ring safely.

Remove – Remove the timed belt protective cover.

Belt – Remove the broken belt, and check for damage.

Loosen – Loosen both pulley bolts; the bolts are positioned on the underside of the pulley.

Remove – Remove the two guide bolts. Remember to fit these after fitting the belt, but tighten them last.

Loosen – Loosen the two guide bolts.

Loosen – Loosen the lock-nut on the adjusting bolt, and thread it all the way out.

Push – Now push the tensioning assembly in all the way so it hits the adjusting bolt.

Set to 90° – Set the deck blades at 90° to each other.

Mark – Now mark the two main blade pulleys and the deck body as per the picture. Marking them with paint gives us a clear reference point when fitting the new belt.

Align – Keep your paint marks aligned and fit the belt to the tension assembly last.

Check – Check your paint marks again; it’s OK if you’re out by one or two teeth.

Routing – This is a typical timed belt routing.

Adjust – Adjust belt tension first, and tighten down the lock-nut. Do not tighten pulley bolts or guide bolts at this stage.

Check – Check belt tension as you adjust. Leave some play in the belt; it should deflect by about 1/2″ at its longest run.

Check 90° – Check that the blades are at 90 degrees. If all is OK, go ahead and fit the guide bolts, but don’t tighten them yet. Tighten the two pulley bolts, and now tighten the four guides.

Rebuild covers and fit the deck in reverse order; that wasn’t so bad!

Related Questions

Why does my deck belt keep breaking? Common reasons new belts keep breaking:

Why does my mower deck shake? Mower decks commonly shake because:

• Engine not at the correct rpm
• Engine not running correctly
• Blades damaged
• Deck belt damaged or worn
• Spindle bearing damaged or broken

As you’re a MacGyver type, you’ll likely find the Riding mower troubleshooting and the Video repair library useful.

Hey, I’m John, and I’m a Red Seal Qualified Service Technician with over twenty-five years experience.

I’ve worked on all types of mechanical equipment, from cars to grass machinery, and this site is where I share fluff-free hacks, tips, and insider know-how.

And the best part. it’s free!