John Deere D170 Problems: Troubleshooting Issues Guide


The John Deere D170’s 54-inch mower deck makes this riding mower a popular choice for homeowners with large lawns. This utility vehicle also behaves beautifully on challenging terrains, but as any other vehicle out there, it can have problems sometimes. This guide covers all you need to know about diagnosing and fixing the most common issues.

Transmission fails, and vibrations are some of John Deere D170‘s most common problems. Other potential issues include engine and steering problems or general mowing trouble. In general, all these issues are easy to fix, and you can prevent them with proper maintenance. 

1. Transmission Failure

Transmission problems affect most lawn mowers regardless of their make and model. The John Deere D170 transmission is hydrostatic, meaning that it converts mechanical power into fluid power that is then reconverted into shaft power.

The Kanzaki Tuff Torq HD K46 that equips the D170 is reliable in general, and you can expect it to last about 5,000 hours, on average. However, it can still fail sometimes.

The most common K46 transmission problems include mechanical failure due to a clogged or broken component.

Mechanical Failure

Hydrostatic transmissions come with multiple advantages, but they have one big drawback: they are made of many moving parts that can cause problems.

For instance, a broken hose or clogged filter can cause the transmission to fail. You must also purge the system regularly and change old oil to prevent problems such as burning smells or leaking fluids. The hydraulic and steering fluids must also be changed.

Signs of a broken transmission include leaking fluids, foul smells, and also the inability to change gears (or you may notice that the vehicle struggles to change gears).

Depending on the cause, you may be able to repair the transmission or may have to replace it with a new one.

Remedy

If you suspect a transmission failure, you have to remove it from the mower, inspect it, and replace it if necessary.

1. Remove the transmission 

Raise the back of your lawnmower with a mower lift or floor jack. Get under it and remove the transmission cover bolts with a socket wrench.

Take off the cover carefully – fluids may spill from the hydrostatic transmission. Once you’ve removed the plate, unfasten the bolts that secure the transmission to the tractor and take it off.

2. Inspect the old transmission

Check the transmission and see if there is anything broken – if anything’s broken, your riding mower needs a transmission upgrade.

If nothing’s broken, clean it from grime and gunk. Replace the hydraulic fluid with fresh fluid for a smoother operation.

3. Reinstall the transmission 

Whether you’re installing the same transmission after you’ve cleaned it or you’re replacing it with a new one, start by fastening it under the mower. Place the cover plate over it and secure it in place. Fill the tray with new hydraulic fluid to finish the job.

2. D170 Won’t Start

The transmission is one of the things that can prevent your JD D170 from working properly, but not the only one. If your vehicle doesn’t start, you should investigate the following potential culprits.

Fuel Problems

There are various things that can go wrong with the fuel – preventing your riding mower from starting or making it difficult to start – but you’d be surprised how many people try to start the machine on an empty tank.

When you first start the mower after a longer period of inactivity, don’t forget to check the fuel level and its quality.

Old gas could also prevent the machine from starting, and so does the wrong grade gasoline.

Remedy

The remedy varies based on the problem. If the tank is empty, you must add fuel. Drain old fuel and change it with fresh gasoline if the gasoline in the tank has a dark color or unusual smell.

If you’re not sure what type of fuel is in the tank, drain it and replace it with the right gasoline type.

Water or Air In Fuel System

Water or air in the fuel system can cause hiccupping, stalling, and refusal to start. The only way to deal with this issue is to get rid of either the air or the water in the system.

Remedy

  1. Park the mower on a flat surface, turn it off, open the hood and disconnect the spark plug.
  2. Drain all the fuel out of the system and let the tank open so it can dry.
  3. Drain the oil and let the tank open so that any water can dry.
  4. Take off the carburetor and empty its bowl. Clean the carburetor with a carburetor cleaner – spray the product until fresh cleaner starts oozing from the carburetor.
  5. Install the carburetor back in its place and fill the oil tank.
  6. Refill the fuel tank and add a bag of fuel stabilizer to help maintain its properties longer and prevent moisture build-up in the tank.

Faulty Spark Plug

Faulty spark plugs are a sort of standard problem on all sorts of vehicles. While this part doesn’t raise major issues, it degrades in time and needs to be replaced about once a year. If you’ve used a low-quality spark plug, it may wear out faster.

Besides problems with the actual part, the electrical wires that help create the spark may also become loose or break.

Remedy

1. Remove the spark plug

Park the mower on a flat surface, stop it and open the hood. Find the spark plug at the front of the mower and remove it with a spark plug socket. If you don’t have a socket, grab it with pliers and pull it out.

2. Inspect the spark plug

Check the spark plug for signs of rust or corrosion. If the tip is black or rusted, wipe it with a paper towel and see if you can clean it. If the component is too worn out, replace it with a new spark plug.

3. Inspect the wires

If there is nothing wrong with the spark plug, you could deal with faulty spark plug wires. Inspect them and tighten any loose ends. If they are broken, repair or replace them with new wires.

Clogged Fuel Filter

John Deere mowers have a fuel filter that prevents residues from getting inside the engine. This filter clogs sometimes, and when this happens, you have to replace it.

Remedy

To change the fuel filter, you’ll need:

  • New fuel filter
  • Clean towels
  • Drain pan
  • Pliers

1. Access the filter 

Open the engine compartment and remove the hood. Find the fuel filter and place the drain pan under it.

2. Remove the fuel filter 

Loosen the hose clamps with a pair of pliers and move them away. Disconnect the fuel filter by pulling out the hoses.

3. Install the new filter 

Place the new filter in the same position as the old one. Push the hoses on the filter ends and secure them with clamps. Replace the hood and start your mower to see if you’ve solved the issue.

Faulty Safety Switch

Like all John Deere mowers, the D170 has a neutral safety switch placed under the brake pedal. Its role is to keep the engine from starting without the pedal being depressed. However, a faulty switch may not sense when the pedal is depressed and prevent the engine from starting at all.

Remedy

  1. Locate the safety switch under the brake pedal and unscrew the bolts keeping it in place.
  2. Disconnect the switch from the wiring harness. Test it with a multimeter; if the resistance is higher than 0.01 ohms, you need a new switch.
  3. Connect the new safety switch to the wiring harness and reconnect the bolts. Your mower should now start.

Carburetor Not Working Properly

Carburetor problems could be the result of a faulty carburetor, plugged carburetor passages, or incorrect adjustments.

Remedy

1. Check the carburetor adjustments 

The first thing to do if you suspect a carburetor issue is to check the adjustments and fix them if needed. Check the idle speed mixture, high-speed mixture, and choke linkage. Turn the respective adjustment screws clockwise or counterclockwise to adjust them correctly.

2. Clean the carburetor 

If the carburetor is adjusted correctly, take it off and clean it with a carburetor cleaner. This operation is simple: spray the product until all grime gets out and fresh cleaner starts oozing out of the carburetor’s passages.

3. Replace the carburetor 

If the carburetor is broken, replace it with a compatible one.

Compression Problems

Low compression is another common reason why your D170 mower might not start.

Remedy

  1. Remove the tractor hood and pull out the spark plug with a spark plug socket or wrench.
  2. Place a compression tester over the spark plug hole and disconnect the ignition coil.
  3. Locate the crankshaft at the front of the engine and grasp it with a wrench.
  4. Turn the crankshaft with the tester in place and read the result. Compare the number with the normal compression (generally about 80 – 140 PSI).
  5. Replace the rings or valves to solve the problem if the compression is lower than that.

3. Lawn Tractor Won’t Move

If the engine runs but the tractor won’t move, the most likely culprit is a locked park brake. Loose or unbalanced mower blades could also be the cause.

Locked Parking Brake

Forgetting the parking brake locked can happen to the best of us. If the engine starts, but the mower doesn’t move, check out the parking brake and unlock it if needed.

Engaged Bypass Valve Lever

Another thing you could forget to deactivate is the bypass valve lever. If it is engaged, disengage it to solve the issue.

Loose or Unbalanced Blades

If the parking brake is unlocked and the bypass valve lever disengaged, you may have to fasten the blades or balance them.

Remedy

Look under the deck and see if the blades are tightened properly. If they are loose, tighten the holding screw.

To balance the blades:

  1. Park the mower on flat ground and disconnect the battery to prevent accidental starts.
  2. Raise the deck to the 3-inch cutting height. This height will give you enough room to work under the deck.
  3. Turn one blade so that it faces towards you. Measure the distance from the ground to both sides of the blade. The distance should be three inches. If the gauge reads another number, the blade needs balancing. Do the same for the other blade, then loosen or tighten the screw to adjust them.
  4. Now, turn one blade with the tip facing toward the front of the tractor. Measure the distance as you did earlier. Do the same with the other blade and adjust the height if needed.

Insufficient Transmission Oil

When the transmission oil level is too low, the transmission might not be able to tell the mower to move even if the engine starts. All you have to do is to top up the transmission oil.

4. John Deere D170 is Vibrating

Vibrating is one of the most frequent machine problems you can get on a JD D170. In addition to the engine troubleshooting, there are a few other components you should check.

Belt

The traction drive belt connects the engine crankshaft to the transaxle pulley that drives the rear wheels. When this belt is worn out or damaged, it can cause the mower to vibrate.

Remedy

  1. Park the mower and disconnect the spark plug.
  2. Raise the mower with a floor jack and disconnect the cutting deck.
  3. Remove the traction drive belt from the pulleys and pull it out.
  4. Install the new drive belt
  5. Reattach the cutting deck and spark plug.

Pulley

The drive belt is not the only traction component that can cause vibrations. A dirty drive pulley is another possible culprit.

Remedy

You can either clean the pulley or replace it with a new one.

Unbalanced Blades

In addition to preventing the mower from running, an unbalanced lawn mower blade can also cause unusual vibrations in the machine. In fact, due to the high rotating speed, unbalanced blades can put so much strain on the blade shaft, spindle, and engine that they can even damage these components.

Remedy

Balance the blades following the steps highlighted above.

5. Bad or Uneven Cut

A John Deere mower that keeps shutting off is a cause for concern, but so is a mower that produces bad or uneven cuts. There are several potential culprits.

Unleveled Mower Deck

Just like the blades could be unleveled, the mower deck could hang lower on one side and higher on the other side. This would unbalance the blades and make it hard to achieve an even cut.

Remedy

Level the mower deck in the same way you would level the blades – use a gauge to measure the distance to the ground and loosen or tighten the screws to adjust it.

Tire Pressure Issues

Low tire pressure or uneven pressure in the tires can also cause balance problems and compromise the cut quality.

Remedy

Park the mower on flat ground and measure the tire pressure. The pressure should be 12 PSI in all tires; if you get another number, adjust the pressure accordingly.

Incorrect Rollers Height

The riding mower’s rollers are placed on the cutting deck (the small wheels under the deck). Check their height and make sure they’re all leveled.

Remedy

Adjust the height of the roller or, if the wheels don’t have the same size, replace them with new rollers.

High Speed

Traveling too fast can result in uneven cuts and even lawn scalping. You can solve the problem by reducing the speed.

Blunt Blades

Lastly, your mower may not do its job properly because the blades need sharpening. Blunt blades will tear the grass rather than cut it, damaging your lawn.

Remedy

1. Remove the blades 

Park, the mower, disconnect the battery or spark plug to prevent accidental starting, and remove the cutting deck. Remove the blade bolts with a socket wrench and take the blades off.

2. Sharpen the blades 

Secure a blade on a bench vise in your garage or workshop. Sharpen it with a grinder until you can easily cut through paper.

While sharpening, use a moderate speed and make sure to maintain an angle between 45 and 65 degrees.

Once you’ve sharpened one half of the blade, flip it 180-degrees to sharpen the other side. Do the same with the other blade.

3. Replace the blades on the mower

Mount the blades back and reinstall the cutting deck. Use a gauge to balance the deck and blades, then set the desired cutting height and test the mower.

In Summary

Issues in D170 54″ truck are generally easy to fix, but you can prevent them through maintenance. Plan a maintenance schedule and stick to it to prevent transmission, engine, or cutting problems. If issues arise, we hope this guide can help you deal with them efficiently.

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