Owner's Manual
Page 372
... change the thermostat for evidence of the rubber. Other designs may cause heat damage or mechanical wear. Ensure nylon tubing in unsatisfactory coolant performance, poor gas mileage, and increased emissions. Hard or soft spots, brittle rubber, cracking, tears, cuts, abrasions, and excessive swelling indicate deterioration of heat and mechanical damage. Inspect hose...
... change the thermostat for evidence of the rubber. Other designs may cause heat damage or mechanical wear. Ensure nylon tubing in unsatisfactory coolant performance, poor gas mileage, and increased emissions. Hard or soft spots, brittle rubber, cracking, tears, cuts, abrasions, and excessive swelling indicate deterioration of heat and mechanical damage. Inspect hose...