Troubleshooting and Maintaining an 81 International S1700

[MikePhua]

The International S1700 is a popular medium-duty truck, widely used in the construction, transportation, and delivery industries. Known for its durability and powerful performance, this truck model is designed to handle a range of tasks, from hauling materials to delivering goods. However, like any vehicle, it can encounter various issues over time. In this article, we will delve into common problems with the International S1700, particularly from the engine to the electrical systems, and provide tips for troubleshooting and maintaining the truck.
Overview of the International S1700
The International S1700 was built by International Harvester, later known as Navistar, a leader in the heavy truck manufacturing industry. First introduced in the 1980s, the S1700 was designed to offer a powerful, reliable solution for medium-duty trucking needs. It was typically equipped with a variety of engine options, including diesel and gasoline variants, to suit different applications.
The truck features a sturdy chassis, capable of carrying heavy loads while providing the driver with comfort and control. Its use of a mechanical engine, easy-to-maintain components, and relatively simple design made it a staple for fleet managers and owner-operators.
Common Problems with the International S1700
Despite its strong reputation, the S1700, like any vehicle that has been in service for several decades, can develop issues over time. Below, we’ll go over some of the most common problems owners of the International S1700 experience, and provide insights on how to solve them.
1. Engine Starting Problems
Symptoms: The engine may be slow to start or fail to start altogether. This could be accompanied by unusual noises or a lack of response when turning the key.
Possible Causes:

• Faulty Fuel System: The S1700’s diesel engines rely heavily on the fuel system, and any issues with fuel injectors, fuel lines, or the fuel pump can cause difficulty starting the engine.
  
• Weak Battery: A weak or dead battery is a common culprit in starting problems, especially if the truck has been sitting idle for an extended period.
  
• Glow Plug Issues: In diesel engines, glow plugs are essential for cold starts. If one or more glow plugs are faulty, the engine may struggle to start, especially in colder temperatures.
  

Solutions:

• Inspect the Fuel System: Check the fuel lines for leaks or blockages. If the injectors or fuel pump are clogged or malfunctioning, replace them.
  
• Check the Battery: Test the battery and replace it if it’s not holding a charge. Make sure the battery connections are clean and free of corrosion.
  
• Test the Glow Plugs: Inspect the glow plugs and replace any that are damaged or faulty.
  

2. Transmission Slipping or Shifting Issues
Symptoms: The truck may exhibit difficulty shifting gears, or the transmission might slip out of gear, especially under load.
Possible Causes:

• Low or Dirty Transmission Fluid: Insufficient or old transmission fluid can cause the transmission to behave erratically, including slipping or delayed shifting.
  
• Worn Transmission Parts: Over time, parts inside the transmission such as the clutch, bearings, or gears can wear down, leading to poor shifting performance.
  
• Faulty Linkages or Cables: The truck's manual transmission relies on precise linkage adjustments. If these linkages become misaligned, shifting can become difficult.
  

Solutions:

• Check the Transmission Fluid: Check the fluid levels and condition. If the fluid is low or dirty, flush the system and refill it with the recommended fluid type.
  
• Inspect the Transmission: If the problem persists after fluid changes, it may be necessary to inspect the internal components of the transmission for wear. Worn parts might need to be replaced.
  
• Adjust the Linkages: Ensure the transmission linkages or cables are properly aligned and adjusted.
  

3. Electrical System Failures
Symptoms: The truck may experience issues such as malfunctioning lights, non-functional gauges, or complete electrical failure.
Possible Causes:

• Blown Fuses: A blown fuse can prevent certain electrical systems from functioning, including lights, the alternator, and dashboard gauges.
  
• Faulty Alternator: If the alternator is not charging the battery correctly, the truck will eventually experience electrical issues.
  
• Corroded Wiring: Corroded or frayed wires, particularly in the truck’s engine bay or undercarriage, can cause intermittent electrical issues.
  

Solutions:

• Replace Blown Fuses: Identify any blown fuses and replace them with the correct size and rating.
  
• Test the Alternator: Test the alternator to make sure it is charging the battery properly. If the alternator is faulty, it should be replaced.
  
• Inspect the Wiring: Look for any visible signs of corrosion or damage on the wiring. Replace or repair any damaged sections.
  

4. Brake System Issues
Symptoms: Reduced braking power, unusual noises when applying brakes, or a soft brake pedal.
Possible Causes:

• Air in the Brake Lines: Air in the brake lines can cause the pedal to feel soft and reduce braking efficiency.
  
• Worn Brake Pads or Shoes: Over time, brake pads and shoes can wear down, reducing their effectiveness.
  
• Leaking Brake Fluid: A brake fluid leak, either from the master cylinder or brake lines, can cause a loss of braking power.
  

Solutions:

• Bleed the Brakes: If there is air in the brake lines, it needs to be bled out to restore proper braking pressure.
  
• Replace Brake Pads or Shoes: If the brake pads or shoes are worn down, replace them with new ones. Always ensure that the replacements are of the correct specifications.
  
• Check for Leaks: Inspect the brake lines for any leaks and replace any damaged components.
  

5. Overheating Issues
Symptoms: The engine temperature rises above normal levels, or the truck may experience loss of power when it overheats.
Possible Causes:

• Low Coolant Levels: Insufficient coolant can cause the engine to overheat quickly.
  
• Faulty Radiator or Cooling System: A blocked radiator or malfunctioning thermostat can prevent proper coolant flow, leading to overheating.
  
• Water Pump Failure: If the water pump is not working, coolant cannot circulate through the engine properly, causing it to overheat.
  

Solutions:

• Check Coolant Levels: Ensure the coolant is at the proper level and that it’s in good condition. If the coolant is dirty or old, flush the system and refill with fresh coolant.
  
• Inspect the Cooling System: Check the radiator for blockages, and make sure the thermostat and water pump are functioning correctly. Replace any faulty parts.
  
• Test the Water Pump: If overheating persists, the water pump should be tested and replaced if necessary.
  

Regular Maintenance Tips for the International S1700
To avoid most of the common issues with the International S1700, regular maintenance is essential. Below are some key maintenance tips to keep your truck running smoothly:

1. Perform Regular Oil Changes: Change the engine oil and filters as recommended by the manufacturer to keep the engine running clean and efficiently.
   
2. Inspect the Suspension: Check the suspension regularly for wear and tear, especially the shock absorbers and leaf springs.
   
3. Check Tire Pressure: Under-inflated tires can reduce fuel efficiency and increase wear on suspension components.
   
4. Clean the Air Filter: A clogged air filter can reduce engine efficiency and lead to power loss. Clean or replace the filter regularly.
   
5. Lubricate Moving Parts: Regularly lubricate the chassis, steering components, and drive shaft to reduce wear and tear.
   

Conclusion
The International S1700 is a reliable and powerful medium-duty truck, but like all machinery, it requires regular maintenance and attention. Understanding common problems such as engine starting issues, transmission slipping, brake failures, and electrical system malfunctions will help you troubleshoot problems quickly and effectively.
With proper care, the International S1700 can continue to serve its purpose for many years. Whether you’re handling heavy cargo or working on a job site, following maintenance schedules and addressing issues promptly will ensure that your truck performs optimally.