Engine - Poor Fuel Economy/Poor Heater Performance

Article No. 86-17-12


STALLS AT IDLE - STUCK THERMOSTAT


FUEL ECONOMY - LOW - STUCK THERMOSTAT


HEATER - POOR PERFORMANCE STUCK THERMOSTAT

FORD 1985 ESCORT, TEMPO, MUSTANG, THUNDERBIRD, FORD, LTD

LINCOLN-MERCURY 1985 LYNX, TOPAZ, CAPRI, COUGAR, MERCURY, MARQUIS, LINCOLN TOWN CAR, MARK VII, CONTINENTAL

CALIBRATIONS: All with EEC IV

Low fuel economy, poor heater performance or stalling at idle during cold weather may be caused by the thermostat being stuck in a partially open position.

Vehicles with large radiator capacities may appear to be operating normally in the service bay, but on the road they may not reach proper operating temperature. This colder operating condition requires additional fuel, causing complaints of poor fuel economy.

1. Perform quick test in Shop Manual, Volume H, and service for stall concerns and poor fuel economy, as required. If code 21 is present, use pinpoint test DE1.

2. If Volume H diagnostics leads to thermostat, check the thermostat as outlined in the Car Shop Manual, page 27-01-6.

3. If the diagnostic procedure on 27-01-6 indicates a faulty thermostat, replace the thermostat.

4. Drain and replace the oil and oil filter.
PART NUMBER PART NAME CLASS

D9AZ-8575-A Thermostat A
OTHER APPLICABLE ARTICLES: None
WARRANTY STATUS: Reimbursable within the provisions of the Warranty and Policy Manual.
OPERATION: SP8575A86
TIME: 1.2 Hrs. - 1.9L, 2.3L, 3.8L 1.6 Hrs. - 5.0L All except Ford, Mercury, Lincoln Town Car
1.1 Hrs. - 5.0L Ford, Mercury, Lincoln Town Car
DLR. CODING: Basic Part No. 8575 - Code: N9, T3