HF35 Oil Pump for Ford CVT Hybrid Transmission The HF35 oil pump is a critical component inside the Ford HF35 eCVT hybrid transaxle, responsible for maintaining stable hydraulic pressure and continuous transmission fluid circulation. It supports clutch engagement, gear lubrication, and cooling during both hybrid and electric driving modes.A worn or failing pump may cause low pressure, delayed shifting, overheating, or transmission warning lights. Our replacement HF35 oil pump