John Deere 35G Excavator Repair Guide

At Fortis HD, we aim to support machine owners and operators in several ways, from offering them high-quality undercarriage replacement parts and heavy equipment tools to sharing our expertise and knowledge in machinery-related topics.

With our John Deere 35G repair guide, you’ll troubleshoot problems related to the engine, electrical and hydraulic system. You’ll find all sorts of possible problems, from the simplest to the least likely, more difficult to verify.

If you want a professional technician to troubleshoot your equipment, visit Tekamo HD to hire a heavy-duty mechanic.

Although it’s obvious, check for fuel in the tank.

Check if the fuel type (winter, summer blend) is incorrect. Drain and refill with the proper blend to solve the problem.

Sometimes, air can enter the system due to leaks, repairs, or other factors, causing poor engine performance. You must bleed that air out of the system. You should bleed the air after each fuel filter change or when the engine has run out of fuel.

Do the following to bleed the air:

1. Make sure the fuel tank is full.
2. Open the right rear service door to access the primary fuel filter and water separator assembly.
3. Check that the fuel shutoff valve is open.
4. Turn the key switch to the ON position for 10 – 15 seconds. The electric fuel solenoid pump will start to bleed air.
5. Wait 30 seconds before trying to start the engine.
6. Start the engine. Check the fuel supply system for leaks. If the engine doesn’t start, repeat the procedure.

A clogged fuel filter will restrict the fuel flow to the engine, affecting its performance. Change it or check if whoever installed it did it correctly.

A clogged fuel filter looks darker due to the accumulation of contaminants and debris. There might be stains or wet spots on the outside of the filter, especially around the connections where fuel enters and exits the filter, and in some cases, the filter may emit a strong odor.

Check also if the air filters are too dirty and replace them if necessary.

Next, take a look at the primary fuel and water filter separator. The first option is to drain the water from the container. Three things might happen if the engine problem persists:

• The filter is clogged.
• The installation wasn’t correct.
• You didn’t prime the filter after the installation.

We recommend changing the O-ring every time you replace the fuel filter to guarantee a proper installation.

Priming refers to filling the separator with fuel and removing any trapped air or water from the filter system before operating the equipment.

To prime the fuel system, turn the ignition on for about 30 seconds (don’t start the engine). Turn the ignition off, and crank the engine for 15 seconds. If it doesn’t start, repeat the first step.

When the engine has a slow cranking speed, it might be due to a poor electrical connection or a low battery. Try first cleaning, tightening the battery and starter connections, and charging the battery. If it doesn’t work, replace the battery.

Finally, make sure the engine oil has the correct viscosity. If not, drain the crankcase and refill.

Engine oil viscosity is vital for cold starts. Using oil with the wrong viscosity can make it too thick or too thin at low temperatures, leading to difficulty starting the engine. Cold starts will be slower, and until it warms up, the engine won’t run smoothly.

If the engine doesn’t crank, clean the battery terminals and connections. Also, look for and adjust loose connections.

Next, inspect the following fuses:

• Check the main relay 10 amp fuse (F4).
• Start 5 amp fuse (F6).
• Engine 5 amp fuse (F16).
• Pilot shut off 5 amp (F17).
• Engine Control Unit 30 amp fuse (F63).

The fuse panel is under the right control lever. Remove the cover to access the fuse panel.

One last reason the engine doesn’t crank can be a low battery level. In that case, charge or replace it.

Poor engine performance can result from clogged air and fuel filters. Replace them, and clean the fuel tank inlet screen.

If the fuel filter doesn’t look too dirty, reinstall it and put the O-ring seal correctly.

Check if there’s air in the system. You already know how to bleed the air from the previous section.

Inspect the engine oil level. If it’s low, it’ll affect the engine’s performance due to excessive friction.

Another reason for performance failure can be low-quality fuel. Drain the fuel tank, change the primary fuel filter and water separator, bleed the air, add fuel, and clean the fuel tank inlet screen. Don’t forget to prime the system before starting up the excavator.

Contact your authorized dealer if the problem concerns the engine speed control system or the injection pump.

Clogged air filters and poor-quality fuel can also cause excessive fuel consumption.

There also might be a leak in the fuel supply system. Find the source and repair it as required.

Finally, check if your machine’s exhaust system is restricted. In that case, contact your authorized dealer.

Your first bet would be to replace the air filters, drain the fuel, and refill with quality fuel of proper grade.

However, a possible reason could also be a worn engine. You’ll need your authorized dealer to diagnose and restore the engine.

Again, the usual suspects are filters, fuel, and air in the combustion system.

Check if the fuel or air filters are clogged or not installed correctly.

Drain the fuel tank, refill it with quality fuel of proper grade, and bleed the air from the system.

Contact your authorized dealer for more complex issues like the engine speed control system, restricted exhaust system, or worn engine.

When the engine is warm, the John Deere 35G idle RPM (Revolutions Per Minute) is approximately 1,300 to 1,350 RPM. If the idle isn’t above 1300 RPM, check the engine speed dial is in the high position.

When you operate the hydraulics functions, the idle might not work. To solve the issue, release hydraulic functions for 10 seconds.

When the engine is warm, the John Deere 35G idle RPM (Revolutions Per Minute) is approximately 1,300 to 1,350 RPM. If the idle isn’t above 1300 RPM, check the engine speed dial is in the high position.

When you operate the hydraulics functions, the idle might not work. To solve the issue, release hydraulic functions for 10 seconds

Like most problems in this post, check if you need to replace the fuel and air filters — remember to bleed the air.

Have you already replaced them? Double-check you put the fuel filter O-ring correctly.

An incorrect fuel type won’t let the engine develop full power. Drain and refill.

If the fuel gets contaminated, drain the tank, change the primary fuel filter and water separator, bleed air, and refill.

Reach your authorized dealer if the root of the problem is a hydraulic issue, a restricted exhaust system, or a worn engine.

Oil with a viscosity grade that doesn’t match the manufacturer’s recommendations prevents the engine from developing full power.

The wrong oil will cause the following issues:

• Inadequate lubrication.
• Poor heat disipation.
• Accumulation of sludge inside the engine.
• Poor oil pump efficiency.
• Impact on the fuel injection timing and combustion processes.

Check the oil level. Ensure the oil viscosity is the correct one.

Inspect the oil filter and replace it if it’s clogged.

Contact your authorized dealer if the oil temperature is too high or you discover the engine leaks.

The cause is an incorrect oil type. Drain and refill.

First of all, check the coolant level.

Secure the radiator cap properly or replace it if necessary.

You should also clean the radiator. Clean the core and side screens with compressed air or water.

If you’re using a pressure washer, take a step back and don’t do it with an angle (stand in front of the radiator). Otherwise, you’ll bend the fins over, restricting the airflow.

Blow all around the fins to remove all the branches, pine needles, and dust to ensure airflow through.

Other possible reasons the coolant temperature is above normal are clogged air filters or a low engine oil level.

Finally, check the way you are operating the machine. Reduce the engine load.

Your equipment uses the wrong fuel type. Drain and refill.

Check for restrictions or dirt in the air intake or exhaust system. Contact your authorized dealer if the exhaust system is cracked or damaged.

Check if the thermostat is working correctly.

When the thermostat gets stuck in the open position, the coolant flows continuously through the radiator, keeping its temperature low and preventing the engine from reaching its optimal operating temperature.

To compensate for the lower temperature, the engine control unit (ECU) increases the amount of fuel in the cylinders to maintain proper combustion. The rich fuel mixture causes incomplete combustion, producing unburned hydrocarbons. The unburned particles cause the exhaust emissions to appear as black or gray smoke.

It’s normal to see some white smoke during engine start-up in cold weather due to condensation and moisture in the exhaust system. It dissipates once the engine warms up.

An incorrect fuel type can also be a reason. Drain and refill.

Call your authorized dealer if the problem is a cracked or damaged exhaust system.

Recharge or replace the battery.

Your machine has one 12-volt battery.

Set your multimeter somewhere above 15 volts. Place the positive (red) lead of a multimeter on the battery’s positive terminal and the negative (black) lead on the negative terminal. According to the multimeter test, the battery charge level is:

• A fully charged 12-volt battery should read around 12.6 to 12.8 volts.
• A 75% charged 12-volt battery should read approximately 12.4 volts.
• A 50% charged 12-volt battery should read about 12.2 volts.
• A 25% charged 12-volt battery should read around 12.0 volts.
• Lower values mean the battery is undercharged.

Another reason could be a damaged fuse. Check the main 60 amp fuse (F61).

First, try cleaning and tightening the connections.

A battery beyond its lifespan won’t take charge. Replace it.

Lead-acid or “flooded batteries” contain water and sulfuric acid (electrolyte solution).

As the battery goes through charge and discharge cycles, some water in the electrolyte solution converts into hydrogen and oxygen gas. Over time, water loss occurs due to the conversion process.

You must periodically check and replenish the water level in the battery cells, especially when working in high-temperature environments.

Check if the hold-down clamp is loose or gone. Replace the battery and tighten or install a new hold-down clamp.

The electrolyte (water and sulfuric acid mixture) freezes and expands in freezing temperatures. The expansion pressures the internal components and the case, producing cracks or ruptures.

No matter the case, we recommend replacing the battery.

Check the water level and add if needed.

If the top of the battery is too dirty or wet, wipe it clean with a dry rag.

Clean, tighten, or replace the cables.

Check also the posts. Wiggle the posts by hand. If they wiggle or turn, replace the battery.

Discard if the battery is undercharged or dead. There might also be a poor cable connection. In that case, clean and tighten the connections.

Check if the starter pinion got jammed in the flywheel gear. You’ll have three options:

1. Repair the ring gear.
2. Replace the ring gear.
3. Replace the whole starter.

In this case, you must replace the starter.

Inspect for damaged or broken battery cables and replace them where necessary.

Also, check for loose or corroded battery or starter cable connections.

If the problem persists, recharge the battery or replace the starter.

The easiest solution is to replace the starter.

However, there may be a malfunction with the key switch or the starter relay. Replace whichever broke.

Look for loose or corroded electrical connections on the battery, ground strap, starter, or alternator.

Check the drive belt. If worn, replace it.

Check the pulleys and the drive belt. Replace them if necessary.

You must adjust the alternator mount if the pulley isn’t worn but misaligned.

One more thing to discard is the alternator bearing. Loosen the alternator belt and turn the pulley by hand. If you feel any roughness, you must repair the alternator.

Check the fuses:

• MONITOR B, RADIO 5 amp fuse (F2).
• MONITOR ACC 5 amp fuse (F11).
• Main 60 amp fuse (F61).

Check TRAVEL ILLUMI 5 amp fuse (F9).

If the angle blade moves without a command from the operator, check the following:

• Lever switches.
• Relays and fuses.
• Solenoids.

Apply the last steps (angle blade suddenly drifts). Also, check the OPTION, ALARM 10 amp fuse (F15).

Make sure the pilot shutoff lever is in the unlocked (DOWN) position.

Check the hydraulic oil level.

To get an accurate oil level reading, park the machine on a level surface with the arm cylinder fully retracted and the bucket cylinder fully extended. Lower the bucket and blade to the ground and stop the engine. The oil level should be between the top and bottom marks on the sight gauge on the hydraulic tank.

Check the PILOT SHUT OFF 5 amp fuse (F17) and replace it if necessary.

One more thing you should do is inspect and clean the suction screen. The suction filter is within the hydraulic tank.

Like before, check the oil level and the suction filter.

Make sure you’re using the proper oil viscosity. A thick oil can slow response times and reduce efficiency, while thin oil won’t provide sufficient protection, resulting in increased wear.

When working in freezing weather, perform a hydraulic warm-up.

CAUTION: Prevent possible injury from unexpected machine movement. Clear the area of all persons before running your machine through the warm-up procedure. If the machine is inside a building, warm the travel circuit first and move the machine to a clear area outside. Cold oil will cause machine functions to respond slowly.

1. Run the engine at 1/2 speed for 5 minutes. Don’t run at fast or slow idle.
2. Travel and swing functions slowly, initially moving only short distances.
3. Operate the boom, arm, and bucket functions. First, move the cylinders a short distance in each direction.
4. Continue cycling cylinders by extending until you reach the entire stroke. IMPORTANT: Holding function actuated for more than 30 seconds can cause damage from hot spots in the control valve.
5. Actuate the bucket curl function (cylinder extend) for 10 seconds and release for 5 seconds. Continue this maneuver for 2-1/2 minutes.
6. Repeat the procedure with the bucket dump function.
7. Operate all hydraulic functions to distribute warm oil in all cylinders, motors, and lines.
8. If hydraulic functions still move slowly, repeat steps 5 and 6.

Are you operating the engine too slow? Remember that the engine drives the hydraulic pump. So, the engine´s speed directly affects the speed at which the pump operates, which, in turn, affects the speed and efficiency of hydraulic functions. Try increasing the engine’s speed.

Check if you need to replace the hydraulic tank cover. A damaged cap can cause pressure loss, reducing performance and slowing operations.

As you work through the maintenance and repair of your John Deere 35G, remember that the right tracks can significantly impact your excavator’s performance and longevity. Take a look at our John Deere mini excavator tracks for a selection of tracks designed to OEM specifications.

Check for clogged filters, a low oil level, and that you are using the correct oil viscosity.

Inspect the radiator and clean it if needed. Also, take a look at the fins and straighten those bent. Bent fins can disrupt airflow through the radiator, making it less effective at dissipating heat from the coolant.

Overheating can be the consequence of contaminated oil. Contact your authorized dealer to help you find the contamination source.

Several things can cause foam formation:

• High or low oil level.
• Incorrect oil type.
• Water or air in the oil.

Remember to contact your authorized dealer if the oil is contaminated.

Lastly, check for kinks or dents in the oil lines.

Is the pilot shutoff lever in the unlocked (down) position?

Inspect and correct pinched or kinked pilot control valve hoses.

Fill the swing bearing with grease.

Remove rocks or mud jammed in the track frame.

The pilot control valve regulates the flow of hydraulic fluid to the excavator’s travel motors or tracks, so check for pinched or kinked pilot control valve hoses.

Try increasing the engine’s speed — because of the link between the engine and the hydraulic system.

Slow engine speeds may lead to stalling the hydraulic system, mainly when the equipment is under heavy load. Stalling can result in sudden stops and jerky movements as the hydraulic components struggle to function at reduced power levels.

Check for rocks or mud jammed in the track frame.

Also, adjust the track sag.

There are two possibilities:

1. Replace the fuel and air filters if clogged.
2. Bleed the air from the fuel system.

If the angle blade moves without you operating it, there might be a problem with the system or circuit relief valves. Check and replace accordingly.

To troubleshoot the lack of movement on one side of the blade, check the hose routing for leaks and inspect the center joint. Repair, add grease, or replace according to the problem.

Although this guide focused on a John Deere 35G mini excavator, several troubleshooting solutions also apply to machines of other makes and models.

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