The clicking sound from the engine, combined with the check engine light and the gas in the oil, points to several possibilities, none of them good. The head gasket is a strong suspect, but it could also be a failed oil pump, a severely damaged engine, or something else entirely. A faulty crankshaft position sensor could also cause clicking and a check engine light.
Here's why some of your suspicions are likely and some aren't:
* Head Gasket Failure: A blown head gasket can allow coolant to mix with oil (creating a milky substance) or combustion gases to enter the oil, which could explain the gas in your oil. It also often causes engine overheating.
* Oil Pump Failure: A failing oil pump wouldn't directly explain gas in the oil. However, lack of oil pressure due to a failing pump can cause serious engine damage that includes clicking sounds.
* Pulley: A failing pulley is unlikely to cause gas in the oil. A slipping or failing pulley will make noise but shouldn't introduce fuel into the oil.
What to do:
1. Stop driving the car immediately. Continuing to drive will cause irreversible engine damage.
2. Have the car towed to a qualified mechanic. This is not a DIY repair. The gas in the oil requires professional diagnosis and repair to avoid further damage and potential fire hazard.
3. Describe the symptoms fully to the mechanic: The gas in the oil, the clicking sound, the check engine light, and the car's mileage are all important pieces of information.
4. Prepare for potentially expensive repairs. The issues you're describing could indicate significant engine damage.
Do not attempt to diagnose or repair this yourself. The problem is serious and requires professional attention.
