Some Ford Fiesta owners report experiencing issues with oil and coolant leaks, accompanied by a toxic smell from the engine after replacing the valve cover gasket and water hose. These problems may stem from oil leaking onto the exhaust system, resulting in a burning oil smell as it vaporizes during operation. Additionally, owners have noted that a leaking valve cover gasket, worn valve seals, or a blown head gasket could be contributing to the oil leak, leading to further unpleasant odors. Some owners also report coolant leaks, which can be indicated by a decreasing coolant level despite pressure tests showing no issues. In cases where the engine is burning oil without visible leaks, internal problems such as a leaking head gasket or oil mixing with coolant may be the cause. Given that these issues persist after recent repairs, it is recommended that owners seek a thorough inspection by a qualified mechanic to identify and resolve the sources of the leaks to prevent further damage and ensure safe vehicle operation.