Water Blowing Out of Radiator on CAT D5 When Started: Troubleshooting and Solutions

[MikePhua]

Introduction
One of the common issues that operators may face with the CAT D5 is water blowing out of the radiator immediately after starting the engine. This issue can be alarming and may lead to engine overheating or potential damage if not addressed promptly. In this article, we will explore the potential causes of this problem and provide troubleshooting steps to help resolve it.
Possible Causes of Water Blowing Out of the Radiator

1. Faulty Head Gasket
   • A blown head gasket is one of the most common causes of water being forced out of the radiator when the engine is started. If the head gasket is damaged, coolant can leak into the combustion chamber or the oil system, creating excessive pressure in the cooling system. This pressure will cause coolant to be forced out of the radiator, sometimes in large quantities.
     
2. Cracked Cylinder Head or Block
   • A crack in the cylinder head or engine block can also allow coolant to leak into areas it shouldn't be, such as the combustion chamber. When the engine is started, the coolant gets pressurized, causing it to force its way out of the radiator. Cracks may not always be visible, and diagnosing this problem may require more advanced testing, such as pressure testing or using a leak detection system.
     
3. Clogged or Blocked Radiator
   • Sometimes, the issue may not be related to internal engine components but rather a blockage in the radiator. If the radiator or cooling system is blocked, it can cause an improper flow of coolant, leading to increased pressure. This increased pressure may result in coolant being blown out of the radiator. Blockages can be caused by debris, corrosion, or mineral buildup within the radiator.
     
4. Water Pump Failure
   • A failing water pump may cause improper coolant circulation within the engine, leading to hot spots and excessive pressure within the cooling system. This can cause the coolant to boil over or blow out of the radiator. A malfunctioning water pump can be identified by checking for unusual noises, poor coolant flow, or visible damage.
     
5. Air in the Cooling System
   • If air has entered the cooling system, it can cause the coolant to foam and expand, creating excessive pressure. When the engine starts, the pressure may force the coolant out of the radiator. This issue can occur after a recent coolant change, a leak in the cooling system, or improper bleeding of the cooling system.
     
6. Thermostat Malfunction
   • A stuck or malfunctioning thermostat can cause coolant to overheat and increase the pressure in the system. This increased pressure may push coolant out of the radiator, particularly when the engine is first started and the coolant temperature is still rising. A thermostat failure can be diagnosed by testing the thermostat’s opening temperature or by replacing it with a new one.
     

Troubleshooting Steps

1. Check the Head Gasket
   • Start by inspecting the head gasket for signs of damage. Look for signs of coolant in the oil (milky appearance) or oil in the coolant. You can also perform a compression test to determine if one or more cylinders are losing compression due to a blown gasket. A combustion leak detector can also be used to check for exhaust gases in the coolant.
     
2. Inspect the Cylinder Head and Block
   • If the head gasket is intact, inspect the cylinder head and block for any visible cracks. This can be done with visual inspection or by using dye penetrant testing. In some cases, pressure testing the cooling system may be required to detect internal leaks.
     
3. Examine the Radiator and Cooling System
   • Inspect the radiator for any visible signs of blockage, corrosion, or leaks. Remove debris from the radiator and clean it if necessary. You can also check the radiator for flow by removing the top cap and running the engine briefly to see if coolant circulates properly.
     
4. Check the Water Pump
   • Inspect the water pump for any signs of leaks, unusual noise, or damage. Check for proper coolant flow and ensure that the pump is circulating coolant effectively. If the pump is not working correctly, it may need to be replaced.
     
5. Bleed the Cooling System
   • If air is suspected in the cooling system, follow the proper procedure to bleed the system. Most CAT D5 models have a bleed valve or screw that allows air to escape from the system. After bleeding, check if the problem persists.
     
6. Replace the Thermostat
   • If the thermostat is suspected to be the cause of the issue, it’s a good idea to replace it with a new one. Thermostats are relatively inexpensive and can prevent overheating issues. Be sure to install the new thermostat in the correct orientation.
     

Conclusion
Water blowing out of the radiator when starting the CAT D5 is typically caused by excessive pressure in the cooling system. The most common causes are a faulty head gasket, cracked engine components, or blockages in the cooling system. By following the troubleshooting steps above, operators can identify and resolve the issue to prevent further damage to the engine. Regular maintenance, including inspecting the cooling system and replacing worn parts, can help keep the machine running efficiently and extend its lifespan.