If one day you’ve noticed that your tractor stopped responding to the travel pedal input or has developed some driving issues, you came to the right place. In this article, I’ll try to help you with troubleshooting and possibly fixing your stubborn tractor.
There are a plethora of reasons why your mower may develop mobility problems. But not to worry, with just the right amount of patience and willingness, you can tame your tractor.
So what could possibly be causing these symptoms?
Let’s start with the easiest problem and move progressively to harder issues.
- This might be comical, but check if the transmission bypass valve lever at the back of your tractor (that’s meant to use when towing or pushing the mower) is disengaged. Normally, it should be pushed in for the tractor to operate properly. If it’s pulled out, your transmission is completely disengaged and is in a constant neutral state.
- Your travel pedal (on models with hydrostatic transmissions). The pedal (that is a u shaped bracing that connects both forward and reverse plastic pedals on a teetering mechanism) can get stuck due to some piece of debris in between the pedal and tractor body. Also, the reverse pedal plastic boot can get cracked or damaged and slip down, in which case it will prevent the driver from accessing the full range of pedal motion in reverse mode, limiting reverse mobility.
- Break pedal. If the brake pedal gets stuck or isn’t getting fully depressed, it will drastically affect the tractor’s mobility. The main causes of brake pedal problems would be, dirt and debris stuck in the brake pedal spring (located atop the left sight of the transmission) or problems with the drive belt/pulleys and tensioner system of which the break pedal is a part.
- The linkage that connects the travel pedal to the transmission. It can get disconnected, preventing the pedal from passing the driver’s input to the transmission. Also, if it develops a deformity, like say banding, from hush exploitative regimes or simply due to its age, it will prevent the full range of pedal motion because of its distorted geometry, thus limiting the driver from accessing all of the tractor’s potential.
- Ignition system. If one of your plugs or coils has gone faulty, it will affect the engine performance, giving it a sluggish response, misfiring, and weak output.
- The fuel system. If your fuel lines or your fuel filter or maybe the carburetor itself gets clogged up that can result in very poor engine performance and extremely weak output. The same goes for a faulty vacuum fuel pump. Keep in mind that the vast majority of fuel system problems take their beginning with improper storing of your equipment.
- Your air filter. Generally speaking, timely maintenance is the key to preventing a lot of the problems with your equipment and air filters aren’t an exception. It’s okay if you haven’t changed for one more season, but if it was sitting in your tractor since the dawn of time; chances are that it may become so clogged up that it won’t pass any air into the engine, resulting in extremely bad performance.
- Drive belt/pulley system. In your tractor, the torque from the engine is passed to the transmission through the drive sheave/drive belt. It can get cracked and stretched out with time, which will make it slip into the pulley system and lose power to that friction. The same situation can happen if your belt tensioner is worn out and is failing to create a proper amount of tension in the pulley system. Typical symptoms are loss of power or complete lack of it. The same can happen if one of the pulleys gets stuck, in which case it starts to create extreme friction to the belt causing it to slip.
- Valve-train problems. Again, maintenance is the key. If you’ve missed one too many scheduled valve clearance adjustment procedures, your valves can get out of whack that they may even get damaged from engine bearings. But even a slight valve mispositioning will affect the engine performance.
- Transmission. If you haven’t been servicing it properly (changing the oil filters and oil in time), it can start to develop some issues. You can suspect a faulty transmission if mobility problems were gradually building up with time; if the problem gets worse as the tractor warms up after a cold start and if you hear grinding or whining noises when you attempt to move the tractor. All transmission problems can basically be boiled down to problems with the hydrostatic unit / the center case, the gear train along with the differential, and the oil level problems due to faulty seals. All these problems take their beginning from bad oil that is full of metal fillings.
- The engine itself. If you haven’t been maintaining your engine for a substantial amount of time, it can develop some serious issues like a spun bearing or chipped cylinder wall. Typically, all of this comes from old oil that hasn’t been changed in years. The engine can also just get old and be in need of piston ring replacement. Either way, end result: is loss of power and poor performance.
Travel pedal and its linkage troubleshooting
First of all, as it’s always a great idea to keep your equipment clean, take a brush and cleanse the whole linkage system that linked the pedal to the transmission and lies underneath the right foot-weld. Note if there isn’t something stuck in the system.
Also, check if some piece of debris hasn’t stuck between the pedal itself and the body of your tractor.
If your pedal teeters loose, you should inspect where the linkage is disconnected and link integrity altogether. The linkage system has two main joints: the first one is connecting the linkage to the teetering pedal (underneath the right foot-weld), and the second one connects it to the transmission lever that is directly connected to the swash plate. Joints should be connected with a bold and a star-lock pin.
You should also inspect the integrity of the linkage itself.
If your pedal has a limited range where you cannot engage forward or reverse mode to the full extent, your travel pedal linkage could be bent or deformed. In such a case, you should replace the linkage.
In case only the revere mode range is limited, you should inspect the reverse pedal plastic boot integrity. Take a look if it hasn’t fallen in. If so, inspect its integrity. Normally the boot shouldn’t be cracked or deformed in any way, and it should sit tightly on the metal pedal.
If there is some sort of problem with your reverse boot, you should replace it. But a temporary solution can be implemented, you can fix its position with a bolt and a washer placed inside the boot’s square hole that would prevent the boot from slipping down the metal pedal rail.
Brake pedal problems:
If your brake pedal does not get fully depressed when you disengage it, you have some problem with the break pedal spring that is located atop the left sight of the transmission.
To troubleshoot any brake problems, you can pull it towards yourself either with your foot behind it or with your arm to offset any possible problems with its spring or drive belt par of the brake pedal mechanism. If the problem disappears when you pull on the brake pedal, the problem lies in the brake pedal.
Take a look at the break pedal springs located atop the left sight of the transmission. Usually, a simple clean up with a brush will do the trick. But if the spring itself got worn out and lose, you should replace it.
If there are no problems with your springs, you should troubleshoot the drive belt, tensioner, and pulley system (find the section below).
Testing the ignition system
Before testing your ignition system, take note of some symptoms that might point out a possible ignition system problem. If in addition to the loss of power and trouble driving you hear that your engine is misfiring and has trouble revving up (chokes on itself), you should test its ignition system.
The ignition system on your tractor consists of spark plugs, coil packs, some magnets on the flywheel, and wiring.
One way to test the whole ignition system is to unscrew the spark plug, put it back in the boot, and ground it by touching the side of the plug to some metal body part of your tractor mower away from the socket (like the frame) and crank the starter (you can use a spark plug tester for that if you have it).
Repeat for the other plug. If you see the spark and hear it clicking when cranking the starter, the ignition system of the corresponding cylinder is fine.
If there is no spark, try changing the spark plug, especially if it’s dirty with residue or looks damaged (you can also test it with an Ohmmeter, it should be between 5 and 15 Ohms); if there is still no spark, the problem lies with your coil pack or wiring.
You can test your coil packs and wiring for continuity with an Ohmmeter and change out the damaged part of your ignition (you will need to disassemble and uninstall the air cooler for that though). Your coil pack may also be in need of recapping; for that, you need to make sure that your coil sits apart from the flywheel magnet by approximately the thickness of a business card.
Troubleshooting the fuel supply system:
A loss of power along with trouble revving up (where the engine chokes on itself) could be also symptoms of fuel system problems. Engine overheating is yet another symptom of some issues with the fuel system.
In any case, you should change your fuel filter, especially if you haven’t done that in a while.
When changing the fuel filter, you can test the fuel flow through the inlet fuel line by unsqueezing it (prepare some containers to avoid spilling the gasoline beforehand). If the flaw was restricted, you should take out your inlet fuel line and clean it with compressed air and degreaser.
Also, note if your fuel lines aren’t leaking (they should be dry and never leak any fuel). If they are leaking, change them.
If merely changing the fuel filter and testing the lines didn’t help, the problem can be in your vacuum fuel pump or the carburetor itself.
The vacuum fuel pump:
First, you need to unplug your spark plug and ground it where the fuel won’t reach it.
To test your vacuum fuel pump and outlet fuel line, you need to unplug the outlet fuel line from your carburetor, squeeze it to prevent unwanted leakage, and direct it into the prepared container to test the fuel flaw (which could be very strong).
Then, crank the starter to see if the fuel is running adequately strong. If it isn’t, you have a problem with either your outlet fuel line or your vacuum pump.
You may want to inspect your vacuum pump for cracks or physical damage to determine if it’s bad.
You can also remove your outlet fuel line, flush it with pressured air, then a degreaser and give it one more chance.
If there’s no flaw, your vacuum fuel pump is dead or clogged very badly
If the rest of your fuel system was fine, yet you’re still not getting fuel into the engine, you should test your carburetor.
In order for you to check your carburetor, you will have to completely uninstall it and take it apart. If it’s clogged up, a thorough cleanup is due. You will need different brushes, a good carburetor cleaner, and also not to forget all those jets (including the needle) and the float bowl.
However, if it’s not just clogged up with fuel residue or dirt and has some serious oxidative/chemical damage from the ethanol in the fuel (especially if it was sitting for a couple of months), it’s better to replace it with a brand new one altogether; because even the ultrasound clean-up may not fix the issue as the physical size of these intricate passages and jets won’t be proper ever again, which may render it completely inoperable.
Another part where the problem may lie is the diaphragm, in which case you need to change it.
You should also check the choke linkage, it should be stranded for the choke to work.
Troubleshooting drive belt, tensioner, and pulley system
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 in 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 may also lie in bad or stuck pulleys. But to inspect all the pulleys, you’ll have to remove the drive belt altogether.
Hydrostatic transmission problems
First, let’s start with the easy problem. It can be a worn-out input shaft pulley that has worn-out splints. Typical symptoms are loss of power and immobility.
As we’ve established earlier, bad oil is the usual suspect with the vast majority of transmission problems.
Bad oil can damage the drive shaft and input shaft seals which could cause oil leakage. The insufficient oil level will fail to provide adequate oil pressure inside the hydrostatic system, and it won’t be able to transmit the energy. The typical symptom is winning, complete immobility, or severe loss of power.
Differential and reduction gear-set gears as well as bearings can get damaged by excessive metal filling in the system. The process rapidly spirals as chipped pieces of gears cause even more destruction. Typical symptoms are insatiable mobility, slipping, and grinding noises.
But the most common problem is, worn-out pump and motor pistons and their ports. Again, the premature wear of these is typically caused by bad oil that is full of metal fillings. The typical symptoms are loss of power, slipping, and whining noises; usually, the symptoms get worse as the transmission and the oil inside warm up.
For detailed transmission troubleshooting, it first should be removed from the tractor and taken apart. Only then the differential, reduction gear set, center case, shaft seals, and bearings can be examined and changed.
Engine and engine-related issues (valve-train)
First of all, change the air filter, especially if you haven’t done that in a while. An old and clogged-up air filter can significantly restrict the airflow to the engine which can drastically affect its performance resolution in power loss and the engine choking on itself under load.
But generally speaking, you should take listen to how your engine works at idle and under throttle input (when stationary) for noticing any problems with it. It should run smoothly and rev effortlessly.
If you hear your engine making some clicking or ticking noises with possible loss of power, your valves could be in need of adjustment.
If you have missed your valve adjustment and have been running with unadjusted valves for a while, they might have gone burned out and damaged; in which case, they should be relapsed.
If your engine burns oil, you will see white smoke coming out of your exhaust and smell a distinctive burning odor; that’s a sign that its piston rings or gaskets have gone bad and should be relapsed.
To make an accurate test of your piston rings, gaskets, and general engine health (if it doesn’t have a chipped cylinder wall), its compression has to measure with a special tool called a compressometer. But this job is better left to a professional serviceman, who won’t only test the issue but also will be able to properly fix it.
If you hear the loud knocking combined with misfiring, loss of power, overheating, and possible smoke; these are the signs that you have a spun bearing in the crankshaft. This is typically a very bad sign, and in such cases, your engine will have to be completely rebuilt or swapped for a new one altogether.
And don’t forget that a lot of these issues could be easily avoided with proper maintenance and timely oil change.