IHI IS-35F Excavator Thermostat Location and Troubleshooting

[MikePhua]

Introduction
The IHI IS-35F is a compact yet robust mini-excavator used in various construction, demolition, and landscaping projects. One of the key components for maintaining engine performance and preventing overheating is the thermostat. This article explores the location of the thermostat in the IHI IS-35F, common issues related to it, and how to troubleshoot problems to ensure your machine operates efficiently.
Location of the Thermostat in the IHI IS-35F

1. Thermostat Function:
   The thermostat is a critical component in the engine’s cooling system, regulating the flow of coolant to maintain the engine’s operating temperature. When the engine is cold, the thermostat remains closed to allow the engine to warm up. Once the desired temperature is reached, the thermostat opens, allowing coolant to circulate and prevent overheating.
   
2. Thermostat Location:
   In the IHI IS-35F excavator, the thermostat is typically located near the engine’s water pump or the coolant pipe that connects to the radiator. In many excavators, including the IS-35F, the thermostat is mounted on the engine block and is positioned between the engine and the radiator hose.
   To locate the thermostat, follow the upper radiator hose towards the engine. You will likely find the thermostat housed in a metal housing connected to the engine. The thermostat itself is usually secured by bolts or screws that allow easy removal for replacement.
   

Signs of a Faulty Thermostat

1. Engine Overheating:
   One of the most common symptoms of a failing thermostat is the engine overheating. If the thermostat gets stuck in the closed position, coolant will be unable to circulate properly, causing the engine to reach dangerous temperatures quickly.
   Solution: If you notice the engine temperature gauge consistently running hot or you see steam rising from the engine compartment, inspect the thermostat for potential issues.
   
2. Coolant Not Warming Up:
   If the thermostat gets stuck in the open position, the engine may take longer to warm up. This can lead to poor engine performance and increased fuel consumption as the engine struggles to reach optimal operating temperature.
   Solution: If the engine seems sluggish and takes too long to reach the desired temperature, check the thermostat to see if it's stuck in the open position.
   
3. Fluctuating Temperature Gauge:
   A malfunctioning thermostat can cause the engine’s temperature gauge to fluctuate rapidly, indicating inconsistent cooling system operation. This is often a sign that the thermostat is failing to regulate the flow of coolant correctly.
   Solution: If you notice the temperature gauge constantly fluctuating between hot and cold, it may indicate a faulty thermostat that requires attention.
   

How to Troubleshoot Thermostat Issues

1. Step 1: Inspect the Temperature Gauge:
   Begin by checking the temperature gauge to see if the engine is running too hot or too cold. If the gauge shows that the engine is overheating, this could be a sign that the thermostat is stuck in the closed position. On the other hand, if the gauge is reading lower than usual, the thermostat may be stuck in the open position.
   
2. Step 2: Check Coolant Flow:
   Check the flow of coolant in the system by looking for signs of leaks or blockages. You can do this by inspecting hoses and checking for coolant at the thermostat housing. If the coolant is not circulating properly, this indicates a problem with the thermostat or the cooling system as a whole.
   
3. Step 3: Remove and Inspect the Thermostat:
   To further diagnose the problem, remove the thermostat from the engine. Check the condition of the thermostat to see if it shows any signs of wear, corrosion, or damage. If the thermostat is stuck open or closed, it needs to be replaced.
   
4. Step 4: Test the Thermostat:
   To test the thermostat, place it in a pot of hot water and observe if it opens when the water reaches the appropriate temperature (typically around 85°C to 90°C for most excavator engines). If the thermostat doesn’t open, it’s defective and should be replaced.
   

Replacing the Thermostat in the IHI IS-35F

1. Step 1: Gather the Necessary Tools:
   Before starting the replacement, gather the tools you will need, including a socket wrench, pliers, a drain pan, and a new thermostat with a gasket. Make sure you have the correct replacement thermostat for the IHI IS-35F model.
   
2. Step 2: Drain the Coolant:
   Before removing the thermostat, you’ll need to drain the coolant from the system. Place a drain pan beneath the radiator and remove the drain plug to allow the coolant to flow out. Be sure to dispose of the coolant safely.
   
3. Step 3: Remove the Thermostat Housing:
   Using a wrench, remove the bolts securing the thermostat housing to the engine block. Carefully detach the housing, and the thermostat should be exposed. Remove the thermostat and gasket from the housing.
   
4. Step 4: Install the New Thermostat:
   Clean the area around the thermostat housing and ensure there’s no old gasket material left. Place the new thermostat and gasket into the housing, ensuring it is seated properly. Reattach the housing and tighten the bolts securely.
   
5. Step 5: Refill the Coolant:
   Once the new thermostat is installed, refill the cooling system with the appropriate coolant. Start the engine and let it run for a few minutes to ensure the coolant is circulating properly and the engine reaches the correct operating temperature.
   

Preventive Maintenance Tips

1. Regular Coolant Inspections:
   Periodically check the coolant level and condition in your IHI IS-35F excavator. Low coolant levels or dirty coolant can affect the thermostat’s ability to regulate engine temperature. Always top off the coolant if necessary.
   
2. Monitor Engine Temperature:
   Keep an eye on the engine temperature gauge while operating the excavator. If you notice any significant temperature fluctuations or overheating, it may be time to check or replace the thermostat.
   
3. Use Quality Coolant:
   Always use the manufacturer-recommended coolant type for your IHI IS-35F. Using the wrong type of coolant or low-quality coolant can lead to corrosion, clogged passages, and thermostat malfunction.
   

Conclusion
The thermostat in the IHI IS-35F excavator is an essential component that ensures the engine operates at the correct temperature. By understanding the location and function of the thermostat, you can effectively troubleshoot and maintain the cooling system. Regular inspections, timely replacement of faulty thermostats, and proper coolant maintenance will help extend the life of your excavator and keep it running at optimal performance.