Hydraulic cooler pressure isolation circuit for a header of an agricultural harvester

An agricultural harvester comprising:

• a reservoir for holding hydraulic fluid;
• a pump operatively connected to the reservoir;
• and
• a header attachable to the harvester, the header comprising:
• a hydraulic cooler pressure isolation circuit comprising:
• a hydraulic fluid cooler,
• a supply line extending from the hydraulic fluid cooler for connecting to the pump of the harvester,
• a return line extending from the hydraulic fluid cooler for connecting to the reservoir of the harvester,
• a drain line operatively in fluid communication with the supply line and the return line for connecting to the reservoir of the harvester,
• a first valve hydraulically connected to the supply line upstream the hydraulic fluid cooler,
• a return valve hydraulically connected to the return line downstream the hydraulic fluid cooler,
• a bypass valve hydraulically connected to the supply line upstream the first valve and to the return line downstream the return valve;
• and
• a second valve hydraulically connected to the return line downstream the hydraulic fluid cooler and upstream the return valve and operatively in fluid communication with the drain line.