Diagnosing the low coolant light on an Isuzu can sometimes be tricky. Low coolant light can be several different issues. It is necessary to be very thorough when inspecting these trucks for the above issue.
• Always perform a visual inspection of the cooling system
• Inspect for proper coolant level of the coolant
• Perform cooling system functional test
• Pressure test cooling system look for external leaks
After performing above procedure and finding no external coolant leak is present, but the coolant level is slightly low the next step would be to test the EGR coolers. Properly testing the EGR coolers requires special tools and may require disassembly of the coolers. Special Tools can be rented or purchased through Tom’s Truck Center. Replace any EGR cooler that is found to be leaking. Isuzu has determined that a stress crack in the EGR cooler can happen if the proper installation procedure and torques are not followed. The proper procedure can be found in our information packets on low coolant diagnosis.
When performing EGR cooler diagnostics and the coolers are not leaking and there is no external leak found, and the coolant level is low Isuzu recommends replacing the injector cups. This procedure requires the use of special tools and can be done with the cylinder head installed on the vehicle. The required tooling can be purchased or rented and comes with easy to follow instructions.
You can view the packet HERE.