John Deere 770 Problems (Reasons and Solutions)

John Deere 770 2WD or 4WD compact utility tractor? It’s very durable and often doesn’t cause too much trouble. Despite that, some issues can usually give you a hard time. 

Are you having trouble with your John Deere 770 tractor? Have no clue what to do with it? No, worries, we are here with a complete article on this topic. 

What are the typical John Deere 770 problems you may encounter?

John Deere 770 engines may have some problems like not starting and overheating. Furthermore, you may find problems with shifting beyond 1st gear, locking the gear, and not engaging the PTO in the transmission. Apart from that, hydraulic fluid drains into the transmission. Most of these are fixable. 

Anyway, this is an overview of the whole scenario. Continue reading for the complete guideline. 

John Deere 770 Engine Problems

The John Deere 770 has a Yanmar 3TN82-RJX diesel 3-cylinder liquid-cooled engine. This is known for its durability and stability. But even after that, you may encounter some problems with the John Deere 770 engine:

Problem  Reason Solution
Engine won’t start Corroded battery terminal Clean the battery terminal.
Blown crank fuse Replace the crank fuse.
Engine overheat  Faulty temperature gauge Replace the temperature gauge.
Malfunctioning radiator Clean or replace the radiator.

Problem 1: Engine Won’t Start 

The engine not starting is probably the most common issue for any sort of engine. Even a very silly reason can cause the engine not to start. 

However, we have found certain reasons that are responsible for the engine not starting. Let’s talk about that here.

Reason 1: Corroded Battery Terminal

In the John Deere 770, a corroded battery terminal is the most common reason behind the engine not starting. Electrical current reaches the starter motor by the ignition cable. And that makes the crank. As a result, the engine gets started.  

But if the battery terminal is corroded, the electrical current can’t reach the starter motor. And because of that, the engine doesn’t start.

Solution: Clean The Battery Terminal 

The only solution for the corroded battery terminal is cleaning it. To clean the corroded battery terminal, you need these tools and materials:

  • Baking soda 
  • Water gun 

Now, follow the steps below:

Step 1: Pour liquid baking soda into the terminal to neutralize the acid.

Step 2: Next, you need to wait until it starts releasing bubbles. When it starts releasing bubbles, wipe it. And then spray water with a water gun.

Step 3: Finally, try to start the engine. Try at least 3 or four times if it doesn’t start on the first attempt. 

If this process doesn’t work, you may need to contact an expert for the solution. 

Reason 2: Blown Crank Fuse

If the crank fuse provides power to the ignition system, a blown fuse can prevent the John Deere 770 tractor from starting. Because the ignition system ignites the fuel in the engine cylinders by providing an electrical spark to the spark plugs.

 A blown crank fuse indicates that it has been overloaded and is no longer functioning, preventing the ignition system from receiving the necessary electrical power. And it’ll result in the engine not starting.

Solution: Replace Crank Fuse

If the crank fuse is blown, then the only solution is to replace it. To replace the crank fuse, you need to follow these steps. 

Step 1: Find the fuse panel. Fuse panels are typically found under the hood, in the operator’s station, or the fuse box near the battery on John Deere tractors.

Step 2: Then, find the blown fuse. A crank fuse is usually labeled as such, or it may be labeled with a description of the circuit it protects (e.g., ignition).

Step 3: The battery’s negative (-) terminal should be disconnected. You should do this to prevent any electrical shock or damage to the electrical system while you are working on it.

Step 4: Next, remove the blown fuse. Depending on the type of fuse panel, you may need to use a fuse puller or a pair of pliers to remove the fuse gently. Install the new fuse. Use a fuse with the same amperage rating as the original one.

Step 5: Reconnect the negative (-) terminal of the battery. And you’re done with replacing the crank fuse. 

If you find these steps difficult, you may need to contact an expert to replace your John Deere crank fuse.

Problem 2: Engine Overheating

Overheating is another problem that can occur in all engines. The John Deere 770 engine, however, has some overheating issues.

John Deere 770 engine overheating
Source: Thriving Yard

Several reasons are responsible for the engine overheating. Here, we’ll discuss the two most probable causes for John Deere 770 engine overheating.

Reason 1: Faulty Temperature Gauge

A faulty temperature gauge can cause overheating in your John Deere 770 if it is not accurately reading the engine’s temperature. 

The temperature gauge may indicate that the engine is running at a cooler temperature than it actually is if it is not reading the correct temperature. 

Due to this, the driver may not realize that the engine is overheating and will continue to operate the vehicle, potentially causing engine damage. 

Solution: Replace The Temperature Gauge

If your John Deere temperature gauge is faulty, you may need to replace it. Replacing the temperature gauge is a complicated task. 

So, to avoid unwanted damage, we recommend contacting an expert to do it. 

Reason 2: Malfunctioning Radiator

There are several ways in which a malfunctioning radiator can cause an engine to overheat. As the engine runs, the radiator dissipates heat generated by the engine.

It will be impossible for the radiator to dissipate this heat if it is not functioning properly and effectively. 

A clogged radiator, a radiator that leaks coolant, or a radiator attached improperly to the engine can all cause this. Moreover, if the radiator fan isn’t working properly, it won’t assist in dissipating heat from the radiator, resulting in overheating.

Solution: Clean or Replace The Radiator

If the radiator is only clogged, then cleaning and unclogging it can be the appropriate solution for it. To clean the radiator, you’ll need the following tools and materials:

  • A garden hose
  • A water spray gun

Let’s start the procedure here:

Step 1: The first step is to shut off the engine and let it cool completely before continuing. Additionally, you should place the tractor in an area that is well-ventilated.

Step 2: The next step is to locate the radiator. Behind the grille of a John Deere 770, it will be located at the front of the tractor.

Step 3: Once you’ve found the radiator, remove the cap from the top. Be careful, as the radiator and coolant inside may still be hot.

Step 4: If dirt or debris is trapped inside the radiator, flush it with water using a garden hose. Any stubborn dirt or grime can also be removed with a radiator flush solution, which you can purchase at an auto parts store.

Step 5: Replace the radiator cap after it has been cleaned and refilled with coolant. Ensure that you use the correct type of coolant for your tractor, as specified in your owner’s manual. Let the tractor run for a few minutes to circulate the coolant and ensure everything works properly.

It’s that simple! Clean your John Deere 770 tractor’s radiator with elbow grease and basic tools.

However, if the radiator is damaged, you may need to replace it. To replace the radiator, you may need to contact an expert. 

John Deere 770 Transmission Problems

Problem Reason  Solution 
Shifting above 1st gear lock gear Dysfunctional clutch linkage Adjust clutch linkage.
PTO not engaging Transmission clutch is worn Replace the transmission clutch.

Problem: Shifting Above 1st Gear Locks The Gears

This is an unusual type of issue in that shifting gear beyond the 1st gear locks the gear. But in the John Deere 770, we’ve found many cases like this. A certain factor is responsible for this problem. Let’s take a look at that.  

Reason: Dysfunctional Clutch Linkage

When the clutch linkage does not function properly, shifting gears, including shifting out of first gear, becomes difficult. 

The clutch may not fully disengage when you shift, causing the gears to remain partially mesh and unable to move freely. Consequently, you cannot shift out of first gear because the transmission becomes stuck.

Solution: Adjust Clutch Linkage

You just need to adjust the clutch linkage to resolve the issue of shifting above 1st gear locks the gears. Here are the steps to follow to do this:

Step 1: Disconnect the clutch cable and slightly loosen the locknut and adjuster.

Step 2: The clutch cable needs to be slowly pulled up. At the time of pulling up, you’ll feel at the point the clutch fork is engaged. And you just need to set the clutch cable on that point. 

If you find any difficulties, it’s recommended to call for a service. Or you can watch this video for a visual guideline:

Problem: PTO Not Engaging

You may find John Deere 770 PTO is not engaging. This problem can happen for various reasons. Here we’ll discuss a specific reason that usually causes PTO not engaging issues in John Deere 770 tractors. 

Reason: The transmission Clutch Is Worn

The transmission clutch may be worn if the PTO does not engage properly.

A worn transmission clutch can’t engage the PTO due to a loss of friction between the clutch plates. And this ultimately causes a loss of performance of the PTO. 

Solution: Replace The Transmission Clutch

If your transmission clutch is worn, then it needs to be replaced. Replacing the transmission clutch is a very complicated procedure, and you’ll need a high level of understanding and knowledge regarding this matter. 

Because of that, we’re recommending contacting an automobile technician for the service. 

John Deere 770 Hydraulic Problems 

Problem Reason  Solution
Oil drain into transmission Pump shaft seal is bad Replace the shaft seal.
Fluid pouring out to the cylinder  The piston seal is damaged Replace the piston seal. 

Problem: Oil Drain Into Transmission

Sometimes it can happen that hydraulic oil is draining into the transmission. In some cases, people face this problem in their John Deere 770 as well. There is a common reason behind this issue. 

Reason: The Pump Shaft Seal is Bad

The pump shaft seal keeps the hydraulic fluid inside the hydraulic tank. But if the seal is blown or goes bad, it can leak or drain the fluid into the transmission. This issue has an easy solution. 

Solution: Replace The Shaft Seal

If your shaft seal gasket is blown or damaged, then it may need to be replaced. To replace the shaft seal, follow the step-by-step instructions below: 

Step 1: Turn off the pump and relieve any pressure in the system. Remove all piping and hoses connected to the pump.

Step 2: Using a flat-head screwdriver or other tools, remove bolts or screws on the pump housing or casing. Be careful not to damage the housing or casing.

Step 3: Find the shaft seal. The shaft exits the pump housing or casing where it’s usually located. You can pry off the old shaft seal with a flat-head screwdriver or other tools. Pump housings and shafts should not be damaged.

Step 4: Use a dry cloth to clean the area around the shaft and pump housing. You’ll need a thin layer of sealant around the shaft. Ensure the new shaft seal is aligned properly before placing it on the shaft.

Step 5: Use a flat-head screwdriver or other tools to secure the shaft seal. Ensure all bolts or screws are tight on the pump housing or casing. Turn on the power and fill the pump with fluid. Check the pump to make sure it’s working.

However, if you find these steps difficult to complete, you can contact a technician for service. 

Problem: Fluid Pouring Out Of The Cylinder

Hydraulic fluid dripping from a John Deere 770’s cylinder could indicate various hydraulic system problems. A faulty or damaged cylinder seal could cause it, such as a damaged or worn hydraulic hose, a malfunctioning hydraulic pump, and a damaged piston seal. 

However, we’ve found the most common damaged piston seal responsible for John Deere 770 hydraulic fluid pouring out of the cylinder. That’s what we’ll discuss here. 

Reason: Piston Seal is Damaged

Piston seal locks all the possible scope between the cylinder so that hydraulic fluid can’t drain out of the cylinder.  But if the piston seal is damaged, it can’t lock the fluid. And fluid pours out of the hydraulic cylinder. 

Below we’ll discuss the solution to this problem.

Solution: Replace The Piston Seal 

The only solution for the leaking hydraulic fluid from the cylinder is replacing the piston seal. You’ll need the following tools and materials to replace the piston seal:

  • Wrench set
  • Socks set
  • Screwdriver
  • A dry damaged cloth

Now follow these steps:

Step 1: Be sure to drain the hydraulic fluid from the system before beginning the repair. As a result, you will be able to remove the cylinder more easily and avoid any accidents or injuries during the removal process.

Step 2: Remove the cylinder from the system using the appropriate tools, such as wrenches or sockets. To reassemble the system properly, label all connections and parts properly.

Step 3: After removing the cylinder, you will need to remove the old seal. Use a flathead screwdriver to remove the piston seal carefully. Afterward, clean the cylinder with a solvent or cleaning solution to remove any dirt or debris.

Step 4: Place the new seal in the same position as the old one. Ensure the seal is aligned properly with the cylinder and follow the installation instructions provided by the manufacturer.

Step 5: Once the new seal has been installed, reassemble the cylinder and reattach it to the system. After the cylinder is reassembled and reattached, refill the hydraulic fluid and test it to ensure it works properly.

Following proper safety procedures and using the appropriate tools and equipment when replacing a hydraulic cylinder piston seal is important. In case you are unfamiliar with the repair process, it is recommended that you seek assistance from a qualified mechanic.

John Deere 770 Electrical Problems 

Problem Reason  Solution
Battery not charging Alternator belt is broken Replace the alternator belt.

Problem: Battery Not Charging

You may find your John Deere 770’s battery is not charging. As a result, all other electrical parts are not working properly. 

This problem is caused by a certain reason, especially in the John Deere 770. We will discuss the problem and its solution here.

Reason: The Alternator Belt is Broken

The alternator belt transfers power from the engine to the alternator, which charges the battery. If the belt is broken, the alternator will not receive any power and cannot charge the battery.

Solution: Replace The Alternator Belt 

It is necessary to replace the alternator belt on your John Deere 770 if it is broken. To replace the alternator belt, you’ll need these tools and materials:

  • A new set of alternator belts 
  • A wrench set

Now here are the steps you can follow to do this:

Step 1: First, determine where the alternator belt and tensioner are. The tensioner, a pulley, applies tension to the belt. And it’s basically located under the main chassis of the John Deere 770 tractor.

Step 2: Then, you need to release the tensioner belt. Use a wrench to turn the tensioner in the right direction (consult the owner’s manual). Remove the old belt by slipping it off the pulleys.

Step 3: Install the new belt by routing it around the pulleys in the correct order. To understand the proper alignment of the belt, have a look at the diagram below.

John Deere 770 belt diagram
Source: Yambo Jp

Step 4: Make sure the new belt is tensioned using the tensioner. Don’t twist the belt; ensure it’s seated properly on all the pulleys.

Step 5: Start the engine and listen closely if you hear any unusual noises or vibrations. Everything should be working correctly if the alternator belt is in good condition.

If these steps are hard to perform, you should contact a professional service provider to replace the alternator belt correctly.


What Years Was The John Deere 770 Made?

Between 1988 and 1989, the John Deere 770 tractor was made. The John Deere 770 tractor came in 2WD and 4WD versions. It’s basically a utility tractor from the 70 compact series. There is 23 horsepower on the engine and 20 horsepower on the PTO. Yanmar produces this tractor for John Deere.

What Is The Most Reliable Tractor Ever Made?

John Deere 770 is one of the most reliable tractors ever. It’s one of the most accepted tractors among farmers all around the world. And this is for stability and durability. Besides that, John Deere tractors come in every type and size.

What Is A Good HP for a Tractor?

a 25 to 30 Horsepower tractor is good for all sorts of farming work. For any type of low and mid-range farming task, it can be the best choice. But if you need a tractor for the high-range, then 40 to 45 hp can be the best for you.


Well, this is all about the John Deere 770 problems. It’s hopefully now clear to you what problems can occur in your John Deere 770. Since most of these problems can be fixed, we’ve also discussed their solutions. 

Whenever you find something difficult to comprehend in your John Deere 770, it’s best to seek professional assistance.

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2 thoughts on “John Deere 770 Problems (Reasons and Solutions)”

  1. My 770 has been running just fine for years. The other day it wouldn’t start after I’d been using it moving gravel. Sounded like the battery was on the way out. Replaced it and she fired right up. Parked in the back yard and there she sits. The dash lights light up, get a couple of clicks and everything goes dead. Even with a jump it did the same. Replaced the starter thinking the solenoid was bad but got the same results. Fuses all look fine. Before I start dismantling the control panel, is there something I’m missing here?

    1. It sounds like you’ve taken some good steps in troubleshooting the issue with your 770, but there could be a few other possibilities to consider before dismantling the control panel. Here are a few things to check:

      Battery Connections: Double-check the battery connections to make sure they are clean and tight. Loose or corroded connections can cause intermittent electrical issues.

      Ground Connections: Ensure that the ground connections from the battery to the chassis and engine are secure and free of corrosion.

      Voltage and Charging System: Use a multimeter to measure the battery voltage before and after attempting to start the engine. A healthy battery should have around 12.6 to 12.8 volts when fully charged. While attempting to start, the voltage should drop, but it should not drop significantly below 10 volts. If the voltage drops dramatically, it could indicate a problem with the charging system or a drain on the electrical system.

      Starter Relay: Check the starter relay, which is usually located in the engine compartment’s fuse box. A faulty relay can cause the symptoms you described. You might try swapping it with a known working relay of the same type to see if that makes a difference.

      Ignition Switch: The ignition switch could be faulty, causing the intermittent power loss. Try jiggling the ignition key while attempting to start the engine to see if there’s any change.

      Safety Interlocks: Some vehicles have safety interlocks that prevent starting if certain conditions are not met (e.g., clutch pedal depressed, parking brake engaged). Make sure these interlocks are functioning correctly.

      Wiring and Harnesses: Inspect the wiring and harnesses around the starter, battery, and ignition components for any signs of damage or corrosion. A damaged wire could be causing an intermittent short or open circuit.

      Starter Solenoid: While you’ve replaced the starter, the issue could still be related to the starter solenoid or its wiring. Ensure that the solenoid is properly connected and that its wiring is in good condition.

      Engine Control Module (ECM) or Control Unit: If there’s an issue with the ECM or control unit, it could be causing the power loss. Check for any diagnostic trouble codes (DTCs) using a code reader or diagnostic tool.

      If you’ve gone through these steps and still haven’t identified the issue, it might be a good idea to consult with a professional mechanic or someone experienced with heavy equipment. They may have specific knowledge about the 770 model and be able to provide more targeted troubleshooting steps.

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