Diesel fuel in your coolant system is a serious issue, often indicating a problem with your injector cups. These cups, which house the fuel injectors, can develop hairline cracks that allow diesel fuel to leak into the coolant. This contaminated coolant will eventually end up in the degas bottle, a common symptom of this problem. A significant leak can lead to an overfilled degas bottle.
To pinpoint the faulty injector cup(s), you’ll need to remove the injectors. After cleaning the injector bores with a lint-free rag, pressurize the cooling system. Coolant present in an injector bore indicates a cracked or leaking cup; the others should remain dry.
Specialized tools are necessary for injector cup removal and installation. A specific tap, threaded for a slide hammer, is used to extract the old cup. A special driver, resembling an injector body, is then used to install the new cup. Due to the specialized nature of these tools and the potential for damage, it’s recommended to have a qualified diesel mechanic perform the injector cup replacement.
Other tasks, such as removing and cleaning the injectors, can be done at home. However, remember to change your oil and perform a coolant flush after the injector cup replacement and before restarting the engine. This will remove any remaining diesel fuel and contaminated coolant from the system. Addressing this issue promptly will prevent further engine damage and ensure the longevity of your vehicle.
