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The Caterpillar 955H is a well-known crawler loader, widely used in construction, mining, and material handling. Known for its powerful hydraulics and versatility, the 955H can face various mechanical and electrical issues as it ages, one of the most common being failure to crank, especially when there is an arc at the battery terminals. This issue can often be linked to multiple causes, such as electrical short circuits, starter motor failure, or even hydro-lock conditions in the engine. This article explores potential causes and solutions for this common problem, giving you a comprehensive approach to diagnosing and fixing the issue.
Understanding the CAT 955H Crawler Loader
The CAT 955H was a significant model in Caterpillar’s series of small to medium-sized crawler loaders, designed for a variety of tasks such as grading, material handling, and digging. The 955H was introduced in the early 1970s and quickly became popular for its robust build and reliable engine performance. Equipped with a diesel engine, the 955H's performance was further enhanced by its hydraulic system, which allowed for easy lifting and digging. However, like any older piece of heavy machinery, it can be prone to electrical and mechanical issues as it ages.
The Role of the Battery and Starter System
The starter motor in any diesel engine, including the one in the CAT 955H, is a critical component. It is responsible for turning the engine over during startup. The system requires the battery to provide a substantial amount of power to engage the starter, which in turn rotates the flywheel to start the engine. When a failure occurs in this system, the machine may fail to crank or start, often accompanied by signs like arcing at the battery terminals.
Potential Causes of the 955H Not Cranking
When you experience a failure to crank or hear an arc at the battery terminals in the CAT 955H, it is crucial to perform a thorough diagnosis. Here are the common causes:
1. Battery Terminal Corrosion or Loose Connections
One of the first things to check when troubleshooting a non-starting issue is the battery and its terminals. Over time, corrosion or loose connections can develop, reducing the efficiency of the battery’s ability to deliver power to the starter motor.
The starter motor itself could be faulty. If the motor’s internal components wear out or become damaged, it can prevent the engine from turning over even when the battery is fully charged.
A weak or dead battery can cause insufficient power delivery to the starter motor, which will result in failure to crank the engine.
Hydro-lock occurs when liquid (usually coolant or fuel) enters the engine cylinders, preventing the engine from turning over. This can occur due to a variety of issues such as a blown head gasket or faulty injector, which allows liquid to enter the cylinder.
The solenoid is responsible for engaging the starter motor when the ignition is turned on. If the solenoid or starter relay fails, it can prevent the starter motor from being activated.
Damaged wiring, blown fuses, or poor electrical connections can interrupt the flow of power to the starter motor and other critical components of the electrical system.
Regular maintenance and inspection are key to preventing starter and electrical issues in the CAT 955H. Here are some proactive measures:
The Caterpillar 955H crawler loader, while known for its durability and reliability, can experience common electrical and mechanical issues such as failure to crank, battery terminal arcing, or hydro-lock. By understanding the potential causes of these issues—ranging from a weak battery to a faulty starter motor or hydro-lock conditions—operators can take proactive steps to diagnose and address problems early. Regular maintenance, including battery care, wiring inspections, and keeping the starter motor in top condition, is crucial for ensuring the machine continues to perform at its best for years to come.
By taking care of the electrical and engine components, you can help prolong the life of the 955H and avoid costly repairs. Whether you're dealing with arcing terminals or a failed starter, knowing the troubleshooting steps and solutions can save valuable time and ensure that your equipment stays reliable on the job site.
Understanding the CAT 955H Crawler Loader
The CAT 955H was a significant model in Caterpillar’s series of small to medium-sized crawler loaders, designed for a variety of tasks such as grading, material handling, and digging. The 955H was introduced in the early 1970s and quickly became popular for its robust build and reliable engine performance. Equipped with a diesel engine, the 955H's performance was further enhanced by its hydraulic system, which allowed for easy lifting and digging. However, like any older piece of heavy machinery, it can be prone to electrical and mechanical issues as it ages.
The Role of the Battery and Starter System
The starter motor in any diesel engine, including the one in the CAT 955H, is a critical component. It is responsible for turning the engine over during startup. The system requires the battery to provide a substantial amount of power to engage the starter, which in turn rotates the flywheel to start the engine. When a failure occurs in this system, the machine may fail to crank or start, often accompanied by signs like arcing at the battery terminals.
Potential Causes of the 955H Not Cranking
When you experience a failure to crank or hear an arc at the battery terminals in the CAT 955H, it is crucial to perform a thorough diagnosis. Here are the common causes:
1. Battery Terminal Corrosion or Loose Connections
One of the first things to check when troubleshooting a non-starting issue is the battery and its terminals. Over time, corrosion or loose connections can develop, reducing the efficiency of the battery’s ability to deliver power to the starter motor.
- Symptoms: Arcing at the terminals, failure to crank, poor engine turnover, or a clicking sound when trying to start the machine.
- Solution: Disconnect the battery terminals and inspect them for corrosion or dirt. Clean the terminals using a mixture of baking soda and water. Tighten the connections securely. If the terminals or cables are damaged, they may need to be replaced.
The starter motor itself could be faulty. If the motor’s internal components wear out or become damaged, it can prevent the engine from turning over even when the battery is fully charged.
- Symptoms: No cranking noise, a faint clicking sound, or a grinding noise coming from the starter when attempting to start the engine.
- Solution: Inspect the starter motor for signs of wear or failure. Test the starter by applying direct voltage to it to determine if it engages. If the motor is faulty, it will need to be replaced.
A weak or dead battery can cause insufficient power delivery to the starter motor, which will result in failure to crank the engine.
- Symptoms: Low battery voltage reading, slow engine turnover, or no cranking at all.
- Solution: Test the battery with a multimeter. A healthy battery should read approximately 12.6 volts when fully charged. If the battery reads significantly lower, charge or replace the battery as necessary.
Hydro-lock occurs when liquid (usually coolant or fuel) enters the engine cylinders, preventing the engine from turning over. This can occur due to a variety of issues such as a blown head gasket or faulty injector, which allows liquid to enter the cylinder.
- Symptoms: The engine will not turn over at all, even with a fully charged battery and functional starter motor. You may hear a significant “lock” when attempting to crank the engine, and the starter motor may struggle to turn the flywheel.
- Solution: To diagnose hydro-lock, remove the glow plugs or injectors to inspect for liquid in the cylinders. If coolant or fuel is found in the cylinders, you will need to address the underlying cause, such as repairing the head gasket or fixing the faulty fuel injector.
The solenoid is responsible for engaging the starter motor when the ignition is turned on. If the solenoid or starter relay fails, it can prevent the starter motor from being activated.
- Symptoms: Clicking sound but no cranking, or complete failure to start the engine.
- Solution: Test the solenoid and relay with a multimeter to ensure they are functioning properly. If either component is defective, it will need to be replaced.
Damaged wiring, blown fuses, or poor electrical connections can interrupt the flow of power to the starter motor and other critical components of the electrical system.
- Symptoms: Intermittent starting issues, failure to crank, or electrical shorts that cause arcing at the battery terminals.
- Solution: Inspect the wiring and fuse boxes for any visible damage or corrosion. Use a multimeter to check continuity in the wiring, and replace any damaged fuses. If the wiring is old or frayed, replace it to prevent further issues.
Regular maintenance and inspection are key to preventing starter and electrical issues in the CAT 955H. Here are some proactive measures:
- Regular Battery Maintenance
Clean the battery terminals regularly to prevent corrosion. Check the battery voltage and replace the battery every few years or as needed. Ensure that the battery is securely fastened to prevent vibration-related damage.
- Inspect and Test the Starter Motor
Periodically test the starter motor to ensure it is functioning correctly. If the machine shows signs of slow cranking, consider having the starter checked by a professional before it fails completely.
- Check for Hydraulic Leaks
Since hydro-lock is a potential issue, regularly inspect the cooling system and fuel system for leaks. Ensure that the coolant and fuel levels are correct and that no liquid is entering the engine cylinders.
- Routine Electrical Inspections
Inspect the electrical wiring, solenoids, and relays for wear or damage. Replacing old or worn electrical components can prevent future problems.
- Use the Machine Regularly
Machines that are not used frequently are more prone to electrical and battery issues. Start and operate the machine regularly to ensure that the engine and electrical systems remain in good condition.
The Caterpillar 955H crawler loader, while known for its durability and reliability, can experience common electrical and mechanical issues such as failure to crank, battery terminal arcing, or hydro-lock. By understanding the potential causes of these issues—ranging from a weak battery to a faulty starter motor or hydro-lock conditions—operators can take proactive steps to diagnose and address problems early. Regular maintenance, including battery care, wiring inspections, and keeping the starter motor in top condition, is crucial for ensuring the machine continues to perform at its best for years to come.
By taking care of the electrical and engine components, you can help prolong the life of the 955H and avoid costly repairs. Whether you're dealing with arcing terminals or a failed starter, knowing the troubleshooting steps and solutions can save valuable time and ensure that your equipment stays reliable on the job site.
