There are a number of reasons, mechanical and otherwise, why a mower won’t run. The good news is that fixing most all of the issues is easy enough for a DIYer to handle.
By Tony Carrick and Manasa Reddigari | Updated Aug 8, 2022 4:03 PM
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Lawn care can be tedious, but once the grass starts growing in the spring, mowing becomes a fact of life in most neighborhoods. When you finally muster the strength to tackle that first cut of the season, there are few sounds as disheartening as that of a lawn mower engine that turns over but doesn’t start.
Before you drag the mower in for repairs or invest in costly replacement parts, first make sure that a clogged air filter, soiled spark plug, damaged safety cable, clogged mowing deck, or contaminated gas isn’t to blame. Work through the following steps, and you may be able to get your puttering grass guzzler up and running again in no time.
A lawn mower repair professional can help. Get free, no-commitment repair estimates from pros near you.
Change the lawn mower carburetor filter.
Your lawn mower’s air filter guards the carburetor and engine from debris like grass clippings and dirt. When the air filter becomes clogged or too dirty, it can prevent the engine from starting. To keep this from happening, replace paper filters—or clean or replace foam filters—after every 25 hours of engine use.
The process for removing the filter depends on whether you are operating a riding or walk-behind lawn mower. For a riding mower, turn off the engine and engage the parking brake; for a walk-behind mower, pull the spark plug wire from the plug. Then, lift the filter from its housing.
The only choice for paper filters is replacement. If you’re cleaning a foam filter, wash it in a solution of hot water and detergent to loosen grime. Allow it to dry completely, and then wipe fresh motor oil over the filter, replace it in its housing, and power up the mower—this time to the pleasant whirring of an engine in tip-top condition.
Husqvarna Riding Mower Not Cranking or Turning Over. Simple Fix
Check the spark plug.
Is your lawn mower still being stubborn? The culprit may be the spark plug, which is responsible for creating the spark that ignites the fuel in the engine. If it’s loosened, disconnected, or coated in water or carbon residue, the spark plug may be the cause of your machine’s malfunction.
Locate the spark plug, often found on the front of the mower, and disconnect the spark plug wire, revealing the plug beneath. Use a socket wrench to unscrew the spark plug and remove it.
Check the electrode and insulator. If you see buildup, spray brake cleaner onto the plug, and let it soak for several minutes before wiping it with a clean cloth. Reinstall the spark plug, first by hand, and then with a socket wrench for a final tightening. If the problem persists, consider changing the spark plug.
Clear the mower deck of debris.
The mower’s deck prevents grass clippings from showering into the air like confetti, but it also creates a place for them to collect. Grass clippings can clog the mower deck, especially while mowing a wet lawn, preventing the blade from turning.
If the starter rope seems stuck or is difficult to pull, then it’s probably due to a clogged deck. With the mower safely turned off, tip it over onto its side and examine the underbelly. If there are large clumps of cut grass caught between the blade and deck, use a trowel to scrape these clippings free. When the deck is clean again, set the mower back on its feet and start it up.
Clear the vent in the lawn mower fuel cap.
The mower started just fine, you’ve made the first few passes, then all of a sudden the mower quits. You pull the cord a few times, but the engine just sputters and dies. What’s happening? It could have something to do with the fuel cap. Most mowers have a vented fuel cap. This vent is intended to release pressure, allowing fuel to flow from the tank to the carburetor. Without the vent, the gas fumes inside the tank begin to build up, creating a vacuum that eventually becomes so strong that it stops the flow of fuel.
To find out if this is the problem, remove the gas cap to break the vacuum, then reattach it. The mower should start right up. But if the lawn mower won’t stay running and cuts off again after 10 minutes or so, you’ll need to get a new gas cap.
Clean and refill the lawn mower fuel tank.
An obvious—and often overlooked—reason your mower may not be starting is that the tank is empty or contains gas that is either old or contaminated with excess moisture and dirt. If your gas is more than a month old, use an oil siphon pump to drain it from the tank.
(It’s important to be careful as spilled oil can cause smoking, but there are other reasons this might happen. Read more about what to do when your lawn mower is smoking.)
Add fuel stabilizer to the tank.
Fill the tank with fresh fuel and a fuel stabilizer to extend the life of the gas and prevent future buildup. A clogged fuel filter is another possible reason for a lawn mower not to start. When the filter is clogged, the engine can’t access the gas that makes the system go. If your mower has a fuel filter (not all do), check to make sure it’s functioning properly.
First, remove the fuel line at the carburetor. Gas should flow out. If it doesn’t, confirm that the fuel shutoff valve isn’t accidentally closed. Then remove the fuel line that’s ahead of the fuel filter inlet. If gas runs out freely, there’s a problem with the fuel filter. Consult your owner’s manual for instructions on replacing the filter and reassembling the mower.
Inspect the safety release mechanism cable.
Your lawn mower’s reluctance to start may have nothing to do with the engine at all but rather with one of the mower’s safety features: the dead man’s control. This colorfully named safety bar must be held in place by the operator for the engine to start or run. When the bar is released, the engine stops. While this mechanism cuts down on the likelihood of horrific lawn mower accidents, it also can be the reason the mower won’t start.
The safety bar of a dead man’s control is attached to a metal cable that connects to the engine’s ignition coil, which is responsible for sending current to the spark plug. If your lawn mower’s engine won’t start, check to see if that cable is damaged or broken. If it is, you’ll need to replace it before the mower will start.
Fortunately, replacing a broken control cable is an easy job. You may, however, have to wait a few days to get the part. Jot down the serial number of your lawn mower, then head to the manufacturer’s website to order a new cable.
Check to see if the flywheel brake is fully engaged.
The flywheel helps to make the engine work smoothly through inertia. When it isn’t working properly, it will prevent the mower’s engine from working.
If it is fully engaged, it can make a mower’s pull cord hard to pull. Check the brake pad to see if it makes full contact with the flywheel and that there isn’t anything jamming the blade so the control lever can move freely.
If the flywheel brake’s key sheared, the mower may have run over something that got tangled in the blade. It is possible to replace a flywheel key, but it does require taking apart the mower.
Look out for signs that the mower needs professional repairs.
While repairing lawn mowers can be a DIY job, there are times when it can be best to ask a professional to help repair a lawn mower. If you’ve done all of the proper mower maintenance that is recommended by the manufacturer, and gone through all of the possible ways to fix the mower from the steps above, then it may be best to call a pro. Here are a few signs that indicate when a pro’s help is a good idea.
- You see black smoke. The engine will benefit from a technician’s evaluation, as it could be cracked or something else might be worn out.
- Excessive oil or gas usage. If you’ve changed the spark plugs, and done all of the other maintenance tasks, and the mower is consuming more than its usual amount of oil or gas, consult a professional for an evaluation.
- The lawn mower is making a knocking sound. When a lawn mower starts making a knocking sound, something could be bent or out of alignment. It may be tough to figure this out on your own, so a pro could help.
- A vibrating or shaking lawn mower can be a sign of a problem beyond a DIY fix. Usually something is loose or not aligning properly.
How to adjust belt tension on a Husqvarna riding lawnmower, step by step
One of the core components of a Husqvarna riding lawnmower is the drive belt. The mower blades are driven by a drive belt that connects them with the engine crankshaft pulley. This belt is also called a blade belt. If the belt malfunctions, the lawnmower won’t move. If the belt is worn out, the lawnmower moves slowly because the belt slips on the pulley. If the belt is loose, it will keep your blades from rotating. All these issues require knowing how to adjust the belt. This article will help to adjust the belt tension with a step-by-step approach.
How to adjust belt tension on a Husqvarna lawnmower, step by step:
- Step 1. Park your lawnmower in a flat location
- Step 2. Disconnect the spark plug
- Step 3. Turn the log lever
- Step 4. Inspection of blade belt
- Step 5. Adjustment of the drive belt
- Step 6. Check the blades
How would you know that your belt needs adjustment or not? There’s a long belt that goes from your blading engagement by your steering wheel down to your mowing deck. That belt stretches over time. This causes the belt to slip. If you feel this, then the belt needs adjustment. If you have a Husqvarna riding mower and don’t know how to tighten the drive belt, don’t panic. This blog explains how to adjust the belt tension on a Husqvarna riding lawnmower. IT will give you an insight into the tools you need, the technicalities you should know, and the precautions you should take.
Step-by-step Guide:
Adjusting the belt tension itself is a relatively simple process. However, opening the mower base and exposing the system can be technical and somewhat complex for newbies. Here the easy-to-follow steps will help you with performing the job at home.
Step 1: Park your mower in a flat location
Place the lawnmower on an even, smooth, and plane location. This helps to get easy access to the underside of your mower. Please do not tilt the Husqvarna lawnmower on its side, as oil can run from the reservoir to the engine’s wrong parts. Use the parking brake to keep it from moving. If you have a lawnmower lift, you can use it to raise the mower so that approaching the base becomes easier.
Tip: Let your Husqvarna mower run in a well-ventilated area for a few minutes before starting. This will warm up the engine and oil. If the belt and pulleys run for a while, they will become easier to move by hand. This will make the task somewhat easier.
Step 2: Disconnect the spark plug
As a safety step, it is good to disconnect the spark plug. That will ensure that the engine does not unintentionally start. You will find the spark plug on one side of the combustion chamber; unplug it. Some people ask if there’s a need to remove the Husqvarna mower’s cutting deck while adjusting your mower or blade belt. It both has advantages and disadvantages. In some types, removing it will make your approach to the belt components easier. For other types, just lowering the mower deck to its lowest position will give you enough room.
Step 3: Turn the log lever.
The log lever serves a single purpose of engaging or disengaging the Husqvarna mower blades. Locate the log lever that is extending from the top of the control panel nearby the steering wheel. It turns at a 90-degree angle as it comes out of the control panel and extends to the right. On the end of the lever, there is a paddle handle. Rotate the log lever by holding the paddle handle away from forward away from you to engage the blades. While operating, if you notice a 2-3 seconds delay instead of a 0.5 seconds delay, the belt is loose. Now, pull the lever back to engage the blades.
Step 4: Inspection of blade belt.
Next, you need to locate the Husqvarna blade belt. You can find it across the belt and pulley system underneath the deck. You can approach it from the mower’s base along with the blades, so you must have your mower on a raised platform. Before adjusting, you must look at your belt and make sure that there are no cracks. Suppose you see some cracks and chunks at this time. It would become critical to replace the belt. Next, you must inspect that your spring arm is working correctly. Make sure that it moves back and forth correctly.
Underneath the deck, check by hand that the spring attached to that spring arm is a bit slack, and the belt is easily stretched by hand. Also, check the sag of the belt as it passes over pulleys. If it is sagging below, it needs tightening. If it feels too tight, you need to loosen it. This will give you a complete analysis that which components must be tightened. over, there is a cable that originates from the blade engagement level all the way down to the mower deck connecting the spring arm. It gets extended over time, so the belt gets loose.
Step 5: Adjustment of mower or blade belt.
Now we can start with the adjustment. At the point where the cables come down and attach to the pulleys, there’s a small bracket from where the cable is adjusted. This is the same point where the cable from the blade engagement lever is connected to the spring arm. As the deck and blades are disengaged, everything beneath the deck is in a slack position. The same screws you need to tighten are the screws over the spring arms. Now take an adjustable wrench and unbolt the screws and washers, push the bracket away from the spring, put the bolts back in position, and tighten them up by wrench. You need to set a proper distance between the bracket and spring to tighten or loosen it.
In the case of Husqvarna, you need a 10 mm wrench for the bracket bolting and unbolting. When you are done with adjusting the belt, push the log lever away from the steering wheel to engage the mower deck and blades and check whether the spring is further stretched by hand or not. In an ideal position, it should be tight without any stretching caused by the hand. The belt has been adjusted. Also, you can always grease the belt while operating. Run it by hand to give it a few cycles. This will help lubricate the pulleys too. In the end, tighten any loose connections the pulley might have. Check all springs if they are free to move.
Step 6: Double-check the Blades.
You need to check if the belt and pulley system is working. Use a pair of heavy safety gloves, twist the mower blades and check if the belt moves over pulleys without lagging or sagging. Reconnect the spark plug, and start the Husqvarna engine. Now you can see if the belt and pulleys are driven correctly. If they are, your blades should be continually moving and instantly startup without any delay.
Note: If you want to loosen the drive belt, you need to push the log lever away from the steering wheel, and you have to pull in the spring arms. You’ll be doing the opposite of what you did for tightening the belt.
Additional safety concerns:
We all are aware that blades can be very unsafe to operate without taking preventive measures. Also, when you are adjusting your drive belt, there are some safety tips that you should take into account.
Always Check the Manual
Always read the Husqvarna manual! Ensure that you know every detail about the drive belt. The manual will give you all the basic details you need. Ensure that the belt you use is specifically made for your model. over, match the numbers on the blade belt with the mower manual. Even a slightly higher or lower number can cause the belt to be too tight or loose. This also reduces the mower’s life.
Double Check the Blades
You should always double-check the blades to see if they’re moving correctly without whirring when you move the lever. This is to make sure that the blades will not start cutting up everything. So, when you move the lever, check the blades’ movement. Also, check them when closing the compartments. If the blades are suck, your belt will immediately break up as you try to start up the mower.
Frequently asked questions:
Why does my belt keep slipping off my lawnmower?
The drive belt may come over a riding mower pulley if it is too loose. This is the reason for its slipping too. As the belt is made from fairly flexible rubber to add heat resistance and flexibility. Over time, the belt gets worn out that elongates the belt. Also, the pulleys are supposed to be adjusted at a fixed distance. Over long-term operation, the distance between them may reduce due to the belt stretch and bolts’ loosening. Both these are the causes of a loose belt.
When should I replace my mower belt?
At first, there is no definite amount of time that a mower belt is supposed to last, but most of the mowers have short intervals, after which a belt requires adjustment. Typically, you should adjust the belt once in a while and replace it every two seasons. If you do hectic mowing in one season, you should replace it. This will help protect other critical internal components.
Does a lawnmower drive belt stretch?
Yes, a Lawnmower belt will stretch because of wear and tear after longer use. The mower blades rotate with high RPMs, so the belt itself rotates very quickly as well. Unlike the drive belt of cars, mower drive belts are less sturdy. It means that over time the belt gets loosened over repeated cycles of heating, cooling, and fast turning.
Final remarks:
A loose drive belt can be the reason for your Husqvarna lawnmower to slow down unexpectedly. Over time the belt will stretch. This will reduce the belt tension and can cause several problems. To keep your Husqvarna lawnmower operating properly, the belt adjustment is something you will come across from time to time. This article gives you an easy to follow guideline to adjust the drive belt on your Husqvarna lawnmower.
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.
How to Replace Mower Deck Belt Husqvarna YTH 2246 Lawn Tractor
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.
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Your Belt Keeps Coming Off Your Husqvarna Mower (Solved!)
Having to stop mowing, get off your mower, and replace your Husqvarna belt because it keeps falling off can get very frustrating. The only way to prevent it from continuing to happen is to find the root cause of the problem.
A Husqvarna mower belt can keep coming off your mower when the deck belt is worn, stretched, or shredded. Excessive vibration can cause a belt to come off your pulleys when a bearing, tensioner bracket, or tensioner spring is worn.
There are additional factors that can cause a mower belt to come off. I have prepared a list of reasons so you can get identify your belt problem.
Reasons Your Belt Keeps Coming Off Your Husqvarna
Loose or Worn Belt
A Husqvarna belt will wear from normal use and it can become loose causing it to come off your pulleys. Inspect your belt and check it for wearing, cracking, or a shiny glazed appearance. It’s time to replace your belt when your belt has any of these conditions.
Belt Keeper Damage
Belt keepers are installed around your pulleys to do just want the name indicates. It helps keep the belt in place. A belt keeper is a rod that sits between 1/8” and ¼” away from the pulley.
Your belt doesn’t touch the keepers. The keepers are rods added as a prevention to keep your belt from slipping off your pulleys.
The keepers can become damaged when slack in the belt hits a keeper and bends it out of place. The belt can then slip off the pulley when your belt keeper is damaged. To fix the keeper, you can attempt to bend the rods into place using vice grips and a hammer.
Shredded Belt
A belt can become shredded and break or come off your Husqvarna’s deck. Most of the time, shredding of the belt occurs when a belt rubs against an object like a belt keeper or bracket on your mower deck. Another reason why your belt may shred is when it isn’t installed correctly.
If your belt is shredded, make sure you have it routed around your pulleys correctly.
Your mower may have a decal on it with a diagram showing the direction in which your belt is to be routed or you can find it in your owner’s manual. Next, check for any brackets or keepers your belt is rubbing against.
When the belt rubs on a metal component, you may find a shiny smooth spot on the metal. Fix the bracket so it no longer rubs.
You may have to replace a bushing on some brackets or need to replace a bracket assembly when the manufacturer doesn’t allow only the bushing to be replaced.
Bad Bearings in Your Pulleys
When your pulleys don’t sit flat and parallel to your mower deck, they can cause a vibration when your belt runs around your pulleys. Bad bearings in your pulleys can be the reason your pulleys don’t sit correctly on your deck.
One side of the pulley may have one side higher off the deck than the other. To check for a bad or failing bearing, spin each pulley by hand.
A good pulley will spin smoothly. You will feel a restriction when you spin a pulley that has a bad bearing. You may also hear a sound coming from the bearing indicating your pulley must be changed.
Idler pulleys have sealed bearings so you will have to replace the whole pulley assembly with the bearing already in place.
Bad Bearing in Your Spindle Housings
Check your spindle housings next as the bearings can go bad causing a vibration when you engage your mower deck. The vibration can knock a belt off your pulley.
Confirm you have removed your ignition key and unplugged your spark plug boot(s) to keep your mower from starting while working under your Husqvarna’s deck.
Wearing a good pair of work gloves to protect your hands from the sharp mower blades, grab each end of the blade. Rock the blade up and down to check for play or movement in the blade.
Movement or a knocking sound suggests a problem in your spindle housings. Remove your spindle housings and inspect for a bad bearing or bad spindle.
You may find you can replace a bearing in the spindle assembly, however some models will require you to replace the whole spindle assembly.
Idler Tensioner Bracket or Spring is Worn
Check out the idler tensioner bracket and spring. This is the bracket that holds the idler pulleys in line. You will typically find a pulley on one side of the bracket and a spring on the other side.
The spring can become weak causing your Husqvarna belt to come off your mower.
The hole in the tensioner bracket where the spring attaches can wear and become larger. This can cause additional vibration in your mower. When you find either a worn bracket or spring, you must replace the worn part.
Debris Interfering with Proper Tension
Debris can collect on top of your deck around your pulleys and tensioner. It is possible for the debris to keep your tensioner pulley from being able to move as designed.
Your belt can become loose when sufficient tension is not kept on your belt causing it to vibrate. It isn’t only important to keep the belt area of your mower deck clean and free of debris for performance reasons, it is also important for safety reasons as well.
Dry debris collected on the top side of your mower deck can catch on fire from the heat of the belt.
Find out more details on cleaning your mower deck in my articles on cleaning your lawn mower and finding and fixing mower deck problems. A clean mower will not only improve performance, but it can also extend your mower’s lifespan.
Debris in the Grooves of Your Pulleys
A Husqvarna mower belt can snap and come off your mower when stress is put on the belt from stretching around additional material.
This can be from mud or small debris stuck in the grooves of a pulley. Check the grooves of your pulleys and clean them if necessary.
Oil or Rust on Your Belt
When your Husqvarna develops an oil leak, oil can get onto the belt and cause it to swell when it is covered in oil for a significant period of time. An oil-covered belt can cause your belt to slip on the pulleys and come off your deck.
Your belt can also be covered in rust from old rusty pulleys. Rust prematurely causes your belt to dry out and crack causing your belt to be more susceptible to breaking.
To fix an oil or rust coverage problem, repair the oil leak and clean any oil or rust off your deck and pulleys. If your pulleys are covered in a lot of rust, replace the pulleys.
Once you have taken care of items contributing to oil and rust on your Husqvarna deck, you should replace your mower deck with a new Husqvarna belt.
In Summary
Husqvarna deck belts can be pricey so the longer you can make them last, the better. Here are a few items that can extend the life of your Husqvarna mower belt to keep it from prematurely wearing or breaking and coming off your mower:
- Clean your mower deck after each mowing to remove debris
- Check for rubbing on deck components
- Keep oil and rust from forming on your belt
- Periodically check your pulleys and spindle housings for bearing failure
- Fix or replace any damaged brackets or belt keepers
Still Having Problems with Your Husqvarna Lawn Mower?
If you are still having problems with your mower, check out my guide on common problems owners encounter with their lawn mowers.
I put together a chart to identify causes and solutions to problems including starting, smoking, cutting, vibrating, dying, and more.
If you don’t feel comfortable troubleshooting and performing repairs on your lawn mower, it’s best to contact your local Husqvarna dealership or lawn mower repair shop for assistance.
You must remain safe and only perform repairs you are mechanically able to perform to avoid injury or further damage to the mower.
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