Hydrostatic lawn mower problems. 5 Husqvarna Hydrostatic Problems & Fixes

Husqvarna Hydrostatic Drive Problems Fixes!

The Husqvarna hydrostatic lawn tractor is a valuable household machine, especially during spring when the lawn grows rapidly. However, like all machines, this lawn tractor periodically develops issues that make mowing your lawn unnecessarily challenging.

So what are the common Husqvarna Hydrostatic Drive Problems to look out for? The Husqvarna hydrostatic lawn tractor may not power on, start smoking, be unable to reverse or move forward, experience transmission failure, or become unsteerable.

These problems can be particularly frustrating if you don’t know why they’re happening or how to solve them. Not to worry, we will explain these problems and how you can resolve them in detail.

  • 1 5 Common Husqvarna Hydrostatic Drive Problems
  • 1.1 Husqvarna Hydrostatic Lawn Tractor Won’t Power On
  • 1.1.1 Defective spark plug
  • 1.1.2 Bad or old fuel
  • 1.1.3 Clogged carburetor
  • 1.2.1 Damaged head gasket
  • 1.2.2 Dirty air filter
  • 1.3.1 Faulty tensioner pulley
  • 1.3.2 Worn-out drive belt
  • 1.3.3 Low or old hydraulic oil
  • 1.4.1 Faulty drive belt
  • 1.4.2 Defective tensioner pulley
  • 1.4.3 Low or old fuel or hydraulic oil
  • 1.5.1 Unbalanced tire pressure
  • 1.5.2 Faulty steering dampers
  • 1.5.3 Worn-out steering components

Common Husqvarna Hydrostatic Drive Problems

Husqvarna Hydrostatic Lawn Tractor Won’t Power On

There are several reasons why your Husqvarna lawn mower may fail to start. Let’s discuss three reasons why your lawnmower may fail to start.

Defective spark plug

Another reason your Husqvarna Hydrostatic machine won’t power on might be because of a faulty spark plug. Your machine’s spark plug ignites the fuel combustion that starts the engine, and when the plug is clogged by carbon —the dark substance that appears at the tip— the spark plug becomes unable to ignite.

Fix: Take out the spark plug and examine it for carbon build-up. Then, clean the terminal with sandpaper or a wire brush. If this does not rectify the problem, it will be best to change the plug.

Husqvarna LGT2654 fix no power fwd/rev and drive belt comes off rear trans pulley over and over.

Bad or old fuel

It’s pretty common for gas to degrade 30 days after buying it. The product of this gas deterioration is a sticky residue that clogs the fuel system, including the fuel filter, carburetor, and fuel line.

Fix: Luckily, fixing this issue is quite simple. Drain the old fuel in the lawn tractor’s tank and fill it with new fuel.

Clogged carburetor

A carburetor controls the amount of air fuel that combusts in the cylinder. However, fuel additives, like ethanol, leave behind sticky substances that clog the machine’s carburetor and restrict the quantity of fuel entering the engine.

Fix: The best fix is to clean the carburetor or replace it (if the damage is unsalvageable). We recommend visiting a skilled technician for this fix. Nevertheless, if you have experience fixing lawn tractors, you can do it.

Tip: Ensure you use the fuel in your Husqvarna’s engine within 30 days to prevent the gas from degrading and clogging essential components on your machine.

Husqvarna Hydrostatic Lawn Tractor is Smoking

Noticing smoke from your machine is a worrying sight —Don’t worry; we know how it feels. If your lawn tractor is smoking, here are possible causes.

Damaged head gasket

A faulty head gasket can cause smoke from your lawn tractor. A damaged head gasket will cause oil and coolant to seep into the machine’s combustion chamber.

Fix: You need to replace the damaged head gasket to stop your machine from smoking.

Dirty air filter

The Husqvarna’s air filter protects the engine from debris. However, as time passes, the air filter may get clogged. This blockage will cause the engine to smoke because it’s not receiving adequate air supply.

Fix: Replacing the air filter is the quickest and most effective way to solve this issue. If your lawn tractor’s air filter is made of foam, you could wash it with soap and water instead.

Husqvarna Hydrostatic Lawn Tractor isn’t Reversing or Moving Forward

Many users report being unable to move or reverse their Husqvarna mower. Let’s find out why this happens.

Faulty tensioner pulley

The tensioner pulley tightens the belt of the mower’s pulley system. If this part fails, the entire pulley system may not work correctly.

Fix: Replace the faulty tensioner pulley in the machine.

Worn-out drive belt

The drive belt is responsible for driving a system of pulleys that makes the machine move. The engine and clutch power the drive belt, and when it becomes defective, your mower will have issues moving in any direction.

Fix: Replace the worn belt. Also, check that the belt is securely wrapped around the machine’s pulleys.

Low or old hydraulic oil

If the hydraulic oil in your lawn tractor is old or too little, the hydraulic system won’t lubricate sufficiently. This insufficient lubrication will cause the machine to operate slowly; in some cases, the machine may fail to move.

Fix: Change or top up the hydraulic oil in the engine.

Husqvarna Hydrostatic Lawn Tractor Transmission Failure

Your lawn tractor may encounter issues with its hydrostatic transmission system. This issue will lead to difficulty when shifting your lawn tractor and hamper its performance.

Faulty drive belt

A faulty drive belt can cause your machine’s pump to perform inefficiently. We recommend checking the drive belt on your lawn tractor at regular intervals to verify that it is in working condition.

Fix: Simply replace the faulty drive belt

Defective tensioner pulley

If the tensioner pulley on your machine is defective, it becomes unable to keep tension on the tractor’s drive belt, leading to transmission issues.

Fix: Replace the tensioner pulley and lubricate the arm.

Low or old fuel or hydraulic oil

Low fuel or hydraulic oil in your lawn tractor will cause your hydraulic system to function poorly, causing weak transmission.

Fix: The fix for this issue is straightforward. First, make sure your machine’s fuel and hydraulic oil are at the right levels, then top up as required. We also recommend changing your fuel or hydraulic oil at regular intervals. It seems easy, right?

Fun fact: Hydrostatic transmissions use hydraulic fluid to shift gears automatically. This is the most common type of transmission found on lawn tractors and is more efficient than other transmission types.

Husqvarna Hydrostatic Mower Steering Out-of-control

You can’t get that perfect stripe of grass if your machine moves haphazardly. So, if your Husqvarna lawn tractor can’t steer straight, it virtually makes the machine unusable. This problem may be down to a few reasons; let’s discuss a few.

Unbalanced tire pressure

When the tire pressure is not balanced, you may notice your machine veering uncontrollably. Remember that you must follow Husqvarna’s recommended tire pressure specifications for the best results.

Fix: Check the tire pressure of the Husqvarna mower and fill the affected tires appropriately. Remember, all the tires on your mower require equal pressure.

Faulty steering dampers

Dampers stabilize the lawn mower when mowing on uneven terrain. If the dampers on your machine are bad, the lawn tractor may steer in the wrong direction.

Fix: Replace the faulty dampers with new ones.

Worn-out steering components

Worn bushings, washers, and gears are another reason the Husqvarna may steer out of control. All these components work to balance the machine, so when they become defective, your mower will not steer properly.

Fix: All you have to do is inspect and replace any defective steering components.

Frequently Asked Questions

How do I set the hydrostatic drive on my Husqvarna lawn tractor?

Push the throttle forward for about five seconds. Then, pull the throttle into reverse and hold for five more seconds. Ensure you repeat this step three times for effective results.

How do you troubleshoot a hydrostatic transmission?

First, check the machine’s oil level, the inline pressure filters, and the relief valves. Then, look at the heat exchanger, pump, and motor case drains for extreme bypassing.

What other Husqvarna hydrostatic drive problems should I look out for?

Your lawn tractor may leak gas when you’re mowing. If you notice this problem, check the carburetor, fuel filter, fuel pump, and fuel tank. If you see any damage on these parts, we suggest you replace them. Additionally, your tractor may vibrate during use. This issue may be due to a faulty clutch, loose bolts in the engine or debris stuck underneath the mower.


As you can see, all these problems have solutions. If your machine is experiencing any of these, get your toolbox and start fixing it!

However, if you’re unfamiliar with how the internal systems of this machine work, you should consult an experienced repairer. Don’t worry; most of these replacement parts are inexpensive, so you won’t have to spend a fortune before you can continue trimming your lawn.

Billy Taylor

I founded Gardenaholic to share my 25 years of experience maintaining lawnmowers tractors. I’ve had enough lawn rage for the both of us, so I’ll help you get rid of yours!

Reasons a Riding Mower Won’t Move Forward or Reverse (Forward or Backward)

It can be discouraging when your lawn mower stops moving and you don’t know what to do. The most likely cause of a moving problem on a riding mower is the hydrostatic drive system.

A hydrostatic riding lawn mower won’t move forward or reverse due to a bad drive belt; bad tensioner pulley; broken tensioner spring; old, low, or hot hydraulic fluid; air in the hydraulic system; or the drive release lever in the bypass position.

I’ll share with you items to check in your hydraulic system along with some non-hydraulic system-related items that may affect the engine causing the mower to die and stop moving.

Remove the spark plug wires and ignition key before starting repairs. Follow all safety precautions found in your operator’s manual.

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Follow all safety instructions provided in your equipment operator’s manual before diagnosing, repairing, or operating. Consult a professional if you don’t have the skills, or knowledge or are not in the condition to perform the repair safely.

articles that may help with your riding mower driving problem:

Reasons a Hydrostatic Riding Mower Won’t Move Forward or Reverse

Drive Release Handle Not in Operating Position

Hydrostatic riding mowers have a drive release so the mower can free-roll. This is especially helpful when your mower has stopped working and you need to push the zero turn onto a trailer.

In order to be able to move the mower forward or reverse, you must have these drive release handles in the “operating” position.

The drive release can be in the form of a lever, push/pull button, or knob. Refer to your owner’s manual for the type of handle you have on your mower and where to locate it.

Missing Key in Axle

If you have recently changed your tire on a riding lawn mower, you may have missed a small key that fell out of the axle. This key appears to be a small narrow bar and must be installed in order for the wheel to move.

Not every mower has a key in the axle, but if yours does and it isn’t replaced, the mower won’t move.

Mower Drive Belt is Worn, Loose, or Broken

Check your mower drive belt to make sure it hasn’t fallen off and is positioned correctly on the pulleys. If the belt appears worn, cracked, or broken, you must replace the drive belt.

Bad Tensioner Pulley

Tensioner Pulleys are often made from hard plastic with a bearing in the center. The pulley can break or the bearing can fail. Check your pulley and replace it if necessary.

Keep the tensioner arm greased so it has some movement and does not seize up. Without proper tension on the belt, the mower won’t go forward or reverse.

Missing Idler Arm Spring

The idler spring places tension on the drive belt. Replace the spring if it is broken or has fallen out of your mower and is now missing.

Low Hydraulic Fluid Level

A consistent hydraulic oil change at the intervals recommended by your manufacturer must be completed to keep your lawn mower transmission system running at its best.

Your mower won’t move forward or backward when running the transmission with old hydraulic oil or low hydraulic oil. If it does move, it may seem very weak while moving.

Again, change your hydraulic oil and filter(s) at the recommended intervals. Don’t forget many manufacturers have a “break-in” period when you are changing your hydro oil a little sooner for the initial oil change.

When your hydraulic oil is low, add more hydro oil until the fluid level reaches the full level when your hydraulic oil is cool. It’s also a good idea to check for hydraulic fluid leaks.

Note: some entry-level zero turns will have “non-serviceable” transmissions which means the hydraulic systems are sealed and you are not able to change your hydraulic fluid. If you are having hydraulic issues, bring your mower into your servicing mower dealership for assistance.

Bad or Hot Hydraulic Fluid

When you operate your lawn mower with bad hydraulic fluid or low fluid, the oil is not able to efficiently lubricate the hydraulic system causing increased friction and overheating of the hydraulic fluid.

Hot hydraulic fluid can also result in more extensive damage.

I highly recommend taking your lawn mower into your local repair dealership if you experience leaking from your hydraulic pump or your mower runs fine when it is cold, but stops running when it gets hot.

Air in the Hydraulic System

After changing hydraulic fluid, you must bleed all of the air out of the system. Air in the system can prevent your mower from moving.

Air can be removed from the system in most lawn mowers by raising the rear drive tires off of the ground and allowing them to spin forward and in reverse until you don’t hear excessive noise while the wheels move at normal speeds.

It is important to refer to your operator’s manual for correct procedures to remove air from your model lawn mower’s hydraulic system.

Procedures not only can change from manufacturer to manufacturer but also from model to model.

Non-Hydraulic Related Items that Can Keep Your Mower from Moving Forward or Reverse

If you don’t find the fault of your moving problems in your hydraulic system, you can check other items that can prevent the fuel and air required to run your engine.

Definitely check out these items if your engine starts to sputter or shuts off so you are no longer able to drive.

  • Battery and Charging System
  • Clogged Fuel Filter and Fuel Lines
  • Clogged Air Filter
  • Dirty Carburetor

To read more about items that can result in your mower stopping while mowing and how to fix them read my article “Reason Your Mower Stopped While Mowing”.

Still Having Problems with Your Lawn Mower?

Lawn mower ownership doesn’t come without its frustrations. Own a mower long enough, you are bound to run into many lawn mower problems including starting, smoking, leaking, cutting, and overheating.

For mower troubleshooting, check out my guide Common Lawn Mower Problems: Solved.


A riding mower won’t move forward due to a worn drive belt, worn tensioner spring, bad pulley, air in the transmission system, or hot, old, or low hydraulic oil.

A riding mower won’t drive when the transmission bypass lever is not in the drive position, the brake is engaged, the axle key is missing, air is trapped in the hydraulic system, or the hydraulic oil is low, hot, or old.

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Ariens Riding Mower Transmission Problems [Troubleshooting Fixes]

Ariens riding lawn mowers have a hydrostatic transmission system that ensures efficient speed change. Like other transmission systems, hydrostatic transmission systems have mechanical components such as drive axles and metal hoses that cause mower operation problems whenever they develop defects.

Proper diagnostics will help you fix Ariens riding mower transmission problems. Most problems will come from belt breakage, transmission pump failure, overheating, and loss of drive at high throttle.

How do I know if my lawnmower transmission is bad?

The most surefire sign you have an issue with your lawn mower’s transmission is if you can’t get the mower to move either forward or in reverse. Zero movement forward is sometimes accompanied by jerky movements due to the failure to create enough transmission pressure.

A more subtle sign of lawn mower transmission problems is the mower slowing down. This is commonly associated with old oil that no longer has the necessary hydraulic properties to facilitate transmission.

Sometimes, your Ariens mower moves normally while producing an irritating, high-pitched noise. This is usually a sign of bad transmission caused by a worn-out drive belt.

Finally, if you notice oil spills on the ground or a foul odor coming out of the engine while operating the mower, the transmission fluid may be leaking. The foul smell is due to the transmission oil leaking into the engine.

Note: White smoke might accompany the foul odor from a running engine when the hydraulic transmission oil leaks into the engine.

What causes mower transmission problems?

The most common causes of mower transmission problems in hydrostatic transmission mowers include old hydraulic oil, cavitation, and a defective drive belt. Other less common causes include a faulty pressure sensor and hydraulic fluid leaks.

Bad hydraulic fluid

Hydrostatic mowers use hydraulic fluid to power the transmission process. Any hydraulic fluid left in the hydraulic system for too long goes bad, resulting in transmission failure.

Hydraulic oil contains an anti-foam additive that decays over time, resulting in the oil soaking up air and air moisture. Unlike fresh oil, such entrained hydraulic oil cannot deliver the pressure required for optimal transmission.

Note: Entraining is the condition whereby air and moisture infuse into hydraulic oil.


Cavitation is a condition whereby the mower’s hydraulic system has air in it. It’s a common occurrence in lawnmowers left sitting idle all winter. The hydraulic pump cannot create adequate pressure to facilitate transmission with more air than oil running through the lines.

Damaged drive belt

Transmission failure in Ariens mowers can also be caused by the drive belt displaced from the drive system pulleys. A worn-out or broken drive belt will also cause transmission failure, and your mower won’t move in either direction.

Note: A common sign of a worn-out drive belt in an Ariens Zero Turn lawn mower is a squealing sound when the mower is running.

Defective pressure switch

Some lawnmower models come with a pressure switch as a security feature that prevents the mower from moving when no one is sitting on it. It works by sensing the weight pressure of the mower operator as soon as they’re seated. A broken or defective pressure switch might not detect when someone’s on the mower’s seat, keeping the mower from moving.

Leaking hydraulic fluid

Forward movement may also be hindered if your hydrostatic transmission mower leaks hydraulic fluid. This can be caused by cracks or wear within the hydraulic system, as explained below.

  • The rubber gasket seals can wear down over time. The resulting cracks lead to oil leaks.
  • The hydraulic oil lines can develop hairline cracks, resulting in slow leaks.
  • The crankcase gaskets can break or develop cracks due to constant pressure.

How to fix Ariens riding mower transmission problems?

To fix hydrostatic transmission problems in an Ariens riding mower, consider replacing the old hydraulic fluid, flushing air from the system, or installing a new pressure switch. Other possible fixes include replacing the damaged drive belt and sealing/replacing the source of the hydraulic fluid leakage.

Drain and replace the old hydraulic oil

  • Position the mower on a level, flat surface to ensure that it drains properly. Place a drain pan underneath the oil drain plug to catch the hydraulic oil.
  • Detach the drain plug by unscrewing it with a socket wrench. Let the mower stay in that position for several days until you’ve drained out all the old, entrained hydraulic fluid.
  • Once all the old oil has drained, fill the reservoir with fresh hydrostatic transmission oil.
  • Finally, clean the oil reservoir cap of dirt and debris to avoid contaminating the transmission system. Replace the cap and reattach the drain plug.
  • Starting the mower to check if the problem has been fixed.

Note: For optimal performance, it’s best to use a hydraulic oil brand that the brand manufacturer recommends.

Flush air out of the system

If your Ariens riding mower doesn’t move due to air inside the lines, fix the issue by flushing the air out.

  • Start by securing the mower in position using jack stands. You can also improvise a restraining blockade using wooden blocks. Meanwhile, ensure you’ve engaged the parking brake, too.
  • Disengage the mower’s transmission as per the manufacturer’s manual. You can turn on the mower and place it in neutral mode before releasing the brakes.
  • Push the throttle forward for five seconds before pulling it to the reverse position for another five seconds.
  • Repeat the forward-reverse cycle at least five times, as doing so helps to flush air out of the transmission system.
  • Power off the mower and re-engage the transmission.
  • Finally, start the mower and drive it forward and reverse to see if there are still any movement issues.

Replace the pressure sensor and drive belt

If the pressure sensor beneath the mower seat is faulty, you should install a new one. Ensure the replacement pressure switch is the same brand as the old one or is compatible with your mower.

Alternatively, you can hire a mower technician to replace the pressure sensor for you at a fee. It will cost 45 on the lower end up to 250 on the higher end, depending on service complexity.

Note: If the mower isn’t moving because of a worn-out or misplaced drive belt, replace the belt, too.

Repair or replace leaking transmission system components

If the transmission issue is hydraulic fluid leakage, locate and seal the leaking part. Due to its complexity, it might be best to call in lawnmower repair experts. You’ll have to replace your leaking crankcase gaskets or gasket seals if the damage is extensive

Ariens riding mower transmission care and maintenance tips

Here are some tips to care for and maintain your Ariens mowers:

  • Change the transmission oil every 400 hours of running the mower.
  • Drain out the transmission fluid at the start of winter and replace it with new hydraulic fluid the following spring.
  • Call a professional lawnmower technician to run periodic diagnostics and give your Ariens mower a clean bill of health.

Husqvarna TS354D Transmission Issue? The Ultimate Garden Tractor Get’s A Glitch!


I’m a trained agriculture and geography teacher with an advanced environmental science degree specializing in planning, monitoring, and evaluation. I this website my knowledge, experience, and hard-passed skills for lawn tools, care, and maintenance with my parents.

Tuff Torq k46 Common problems – Troubleshooting

Some telltale signs that your transmission has gone bad are:

Whining and grinding noises while driving, if the transmission is running only in forward or reverse mode if it is leaking oil if it is working fine after a cold start and loses power as it warms up when problems accumulate gradually with time (a sudden power loss usually indicates that the problem is not related to the transmission).

If you notice these symptoms, this article may help.

Common K46 transmission problems.

Let’s start with a simple problem. Worn-out input shaft pulley with worn splines. Typical symptoms are slow performance and immobility.

As we have established before, bad oil is the usual suspect in most transmission problems.

Bad oil can damage the drive shafts and input shaft seals and cause oil leaks. If the oil level is insufficient, the hydraulic system will not have enough pressure to transfer energy. Typical symptoms are whining noises, loss of power, or complete immobility.

Differential and reduction gear-set gears along with bearings can be damaged by excessive metal fillings in the system. The process quickly spirals as the chipped gear parts cause even more destruction. Typical symptoms are unstable mobility, slipping, and grinding noises.

The most common problem, however, is worn on the pump and motor pistons and their ports. Again, premature wear is usually caused by bad oil full of metal fillings. Typical symptoms are Loss of power, slipping, and howling noise. Symptoms usually get worse as the transmission and the oil in its warm-up.

What can cause problems with your integrated hydrostatic transmission or IHT?

Timely maintenance is usually enough to prevent transmission failure, but the problem is that many tractor manufacturers claim that “their transmissions do not require maintenance,” while the actual transmission manufacturers, like Tuff Torq, have a different opinion than aliens with common sense.

Regrettably, many people are misled by claims that these transmissions are “unserviceable”, increasing the number of premature wear cases.

If you operate your tractor in extreme conditions such as high temperatures, rough terrain, and dust, you need to change the transmission oil even more frequently.

Oil is essential to the gearbox, ensuring the health of all the components in it by providing proper lubrication and cleaning.

However, when the oil in the transmission ages, it begins to lose its viscous ability as it accumulates metal fillings, and interacts with seals and metals. It loses its chemical integrity over time as it goes through friction and high temperatures. Old oil leads to premature wear of transmission components.

Metal filings are a natural by-product of the working transmission. But when the amount of these fillings in the oil exceeds a critical point, the oil becomes a dangerous abrasive substance, causing destruction and death wherever it goes instead of lubrication and rejuvenation.

Catch magnets along with the oil filter protect the transmission from filling, but if they become clogged with metal shavings or other debris, they will no longer protect the transmission. And capacity of these magnets along with the filter is limited.

hydrostatic, lawn, mower, problems, husqvarna

Poor quality “for life” oils used by manufacturers chemically affect gears and other metal parts, destroying their molecular structure.

Of course, if your gearbox is fairly old and out of its resources, it can develop problems even with proper maintenance (though it will happen much later).

Excluding problems with symptoms similar to a transmission failure

Shutdown, loss of power under load, or tractor is unable to move on its own. These symptoms may be caused by other tractor problems.

Engine. Take a listen to how it works. If it runs smoothly in response to throttle inputs with no misfires and no choking under load, look elsewhere for the problem. Otherwise, a thorough inspection of the engine and ignition, and fuel system is required.

If your lawn mower stalls as soon as you put it in gear, you may want to check the seat safety switch which may be broken and unable to detect a driver in the seat causing the engine to shut off.

To test your seat safety switch, lift up your seat, unplug the lead wire terminal from the safety switch and test the switch for continuity with an Ohmmeter in both off and on positions by testing corresponding switch pairs of contacts (there are four contacts that make two pairs, ON and OFF). Change the switch if it’s bad.

If your tractor mower fails to move when you engage the forward travel pedal or loses power when under load, you should also check the drive belt. To check the drive belt, start your engine up and put it on full throttle, then engage the electric PTO switch.

If you hear your blades kick in (spin) immediately after engaging the PTO (in under half a second), your belts are fine; otherwise, when blades kick in with a delay or don’t kick in at all, you have A belt problem, but it can be just a deck belt problem.

To check the drive belt, you’ll have to remove the mower deck first. You need to check the tension (keep in mind that when the brake is engaged, the drive pulley is loose causing the belt to loosen a bit as well). You should change the drive belt if it’s too old/slack and has visible wearing marks on it.

Belt problems can also be caused by bad or stuck pulleys. However, to inspect all pulleys, the drive belt must be completely removed.

Again, this may be strange, but make sure the bypass valve lever on the back of the gearbox (used to tow the tractor) is not pulled out.

If not, it’s probably the gearbox.

What do you need for troubleshooting your transmission?

If you’ve established that the rest of your tractor is fine, and you suspect your transmission, you’ll need to inspect it thoroughly. For that, you’ll have to remove if from the tractor and take it apart.

First, safely park your tractor and remove the mowing deck, jack the tractor up by the tow hitch and put jack stands under its frame (in front of the transmission), disconnect all the lineages (break, travel pedal, bypass valve linkages along with reverse sensor terminal).

Uninstall the drive belt tensioner that sits on the frame atop the transmission and take the belt off of the transmission input shaft pulley. And unscrew the metal reverse sensor plate that sits near the right bracing.

Then carefully place the jack under the transmission, unscrew the two bolts that hold transmission bracings on its sides to the tractor frame along with 4 bolts that hold its axles to the frame at the bottom, and carefully lower the transmission dawn.

You would need 10 mm, 13 mm, and 14 mm (for the reverse sensor plate) sockets and a 13 mm wrench (to hold the axle nuts in place while you unscrew the bolts with a socket).

Taking apart the transmission for a thorough inspection

First, take a look at the exact transmission model on the barcode that’s located on the axle part of the transmission and use it when ordering any parts for it.

hydrostatic, lawn, mower, problems, husqvarna

Take a pair of side cut pliers or snap ring pliers and take the snap ring out of the fan/pulley assembly. Inspect your drive pump pulley, it should spin along with the input drive shaft and should sit tightly on the shaft.

If your pulley spins freely and wiggles on the shaft, it is worn out, has worn-out splints, and should be replaced (it might fix your problem altogether).

Take off your pulley (you may inspect it more closely) and take off the fan.

Upper case transmission picture.

Then place your transmission on an even surface and make it level with the help of some chocks. Locate your oil fill plug (20), it’s a bigger flat plug that sits on the left side of the transmission (do not mistake it for a vent plug), and pry it off with a screwdriver (you can tap the screwdriver upwards around the plug with a mallet if you like to be more gentle).

Take out the filing catch magnet that sits inside, remove the metal base, notice the number of metal filings stuck to the catch magnet and clean it thoroughly.

Measure your oil level with a metal ruler, it should be around 20~25 mm (3/4”~1”) below the lip of the (black cap) port when at room temperature.

If the oil level is lower than that and your catch magnet has little to no fillings on it, you should consider replacing your drive axle and input drive/pump shaft seals (they could be the reason for low oil and bad transmission performance). Take a look at the seal replacement manual here

hydrostatic, lawn, mower, problems, husqvarna

Before taking your transmission apart, prepare a big bucket or some other volume and drain the oil to it through the fill plug for about half an hour. Then place your transmission securely (upside down) with lowercase facing upwards and input driveshaft facing the floor.

Lowercase transmission picture.

Unscrew all the bolts (9) that hold the lowercase to the transmission body with a 12 mm socket. Keep in mind that two center bolts are longer (10) so make a mark on their respective crew holes to know their location for the future.

Once unscrewed, carefully pry lose the lowercase by leveraging specially casted pry points (11) located on the sides of the lowercase body with a large flat-headed screwdriver. Remove the lowercase from the gearbox.

Clean the lowercase and uppercase case foam sealant residue using a degreaser (like brake pad cleaner), a scrubber, an Exacto knife, and a metal brush. Be careful not to get any residual into the uppercase and thoroughly clean the channel around the lowercase mating service.

Inspecting the insides of your transmission

To understand what you are gonna be doing, take a look at this transmission diagram:

First, take a look at your oil filter (12) and a second filing catch magnet (13) located near the differential. If they are very dirty, it can be a bad sign. Remove the oil filter and clean the magnet of the filings.

If the magnet was dirty, inspect your differential (19) and reduction gear set: (22) wiggle the gears around, they should have little to no play; then you can carefully remove your gear train for further visual inspection, noting the position and orientation of every gear and washer

If gears have visible damage to them or visible wearing, they should be replaced. A common symptom of a bad gear train is grinding noises when in motion (also a catch magnet near the differential is a good marker).

If the gear train is fine, the problem lies in your center block (14).

One strong symptom that the problem is within your center block: a prominent wining nose and zero response when you press the travel pedal.

Your options are: to buy a brand-new assembly; disassemble the center block and inspect the motor and its pistons (23), oil pump within the main block and its pistons, IDS valves, motor output shaft (24) and swash plates (they all should fit tightly, have no play and no wearing) then change the parts that went bad; sending your center block for a rebuild to a professional.

I recommend the latter option as the brand-new assembly is pretty expensive and rebuilding it yourself will be extremely time-consuming.

In any case, you will have to remove your center block (14) by unscrewing three 14 mm bolts (15) that hold it in place and prying it out. Be very careful not to lose anything when lifting it out (springs, pins, washers bearings, or valves), note the position of the motor (static) swash plate (25), brake disk (16), brace calipers (17), and brake actuator (26), output shaft bearing and jerky plate (18).

If your transmission is damaged to the point where you have to replace components, if it has broken teeth, worn-out center block, or metal debris in the oil; it is recommended to take everything out and thoroughly clean the case as well as the parts.

On the other hand, if the transmission is in good condition but is just old, you can consider putting in more dense transmission oil (like 10 W40).

Also, you should check the integrity of the drive/pump input shaft (21), its splints should be in great shape and its bearing shouldn’t have any play. And you can check the drive shaft bearings while at it.

Additionally, you may take a look at Tuff Torq repair tips here.

Putting it all back together

Basically a reverse process. First, install (the shafts if you have uninstalled them) the differential (19) and the gear train (22). You should squirt some oil on the gears to prevent them from damage while there is no oil yet. Make sure that nothing is missing and everything is in the right orientation.

Make sure to tighten three 14 mm bolts of the center block to 33 – 40 ft. lb.

Don’t forget to install a brand-new oil filter.

Use a transmission seal-maker to make a seal on the lowercase meeting suffice (don’t forget about hydrostatic and gear chamber separator wall). Put it on the uppercase, tighten 12 mm bolts by hand (put the longest two center bolts first in marked ports) and let it sit for an hour. Then tighten your lowercase bolts to 16 – 18 ft. lb.

Flip the transmission (so that the fill plug is facing upwards) and fill it with 2.3 or 1.9 liters (depending on the K46 submodel) Hy-Gard High Viscosity J20C 10 W30 oil or any other synthetic 10 W30 transmission oil. The oil level should be around 20~25 mm (3/4”~1”) below the lip of the (black cap) port when at room temperature, but you have to pour a little more to account for the air purging procedure.

If you have a universal socket and a strong electric screwdriver, you can purge the air from the transmission by spinning the input drive/pump shaft back and forth with it for 5-10 minutes.

Put the fan, the drive pulley on the pump shaft, the washer, and the fixating c clip. Then follow the transmission uninstallation procedure backward, only do not take the jack stands from under the tractor and don’t lower it just yet (if you haven’t purged the air with an electric screwdriver).

One less step while the tractor is still on the jack stands, purging the air (if you haven’t done it yet) from the transmission. Turn the tractor on and let the transmission work in forward and reverse mode as well as in neutral by pulling the bypass valve lever at the back of your transmission into towing position. Let it run like that for about 15 minutes.

Lower your tractor on the ground and enjoy.

1 thought on “Tuff Torq k46 Common problems – Troubleshooting”

hello.I have a tractor with hydrostatic gearbox K46…I changed the filter and now that I have mounted the whole tractor it goes backwards. I ask kindly what could I have done wrong. thanks.Kind regardsTarcisio Baccichet Reply

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