Damaged Sending Unit Service Procedure

Figure 2:

1. If the sender is damaged, check for an undersized hole in the hex fitting or a mismatch of the hex fitting and the bypass tube.

2. Drain the coolant below the level required to remove the water outlet connection.

3. Disconnect the upper radiator hose from the water outlet connection.

4. Remove the water outlet connection assembly (8594) from the intake manifold and remove the thermostat (8575).

5. Drill out the hole in the hex fitting or the mismatched bypass tube. Use a 3/8" (9.128-9.525 mm) diameter drill, Figure 2.

CAUTION: USE CARE, DRILL POINT MAY DAMAGE THE OTHER SIDE OF THE BYPASS TUBE OR THREAD IN THE HEX FITTING.

6. Flush the water outlet connection to remove any metal chips.
7. Clean the gasket surface on the thermostat housing and on the intake manifold.

8. Position the thermostat, new gasket and thermostat housing on the manifold.

a. Install the two (2) retaining bolts.

b. Tighten the bolts to 15-22 lb.ft. (20-30 N-m).

9. Remove the paint from the first three (3) threads of the hole in which the sender was installed. The suggested method of removing the paint is to use a wire brush or any other suitable means that will not damage the threads.

CAUTION: DO NOT USE A TAP TO REMOVE PAINT.

10. Install a new water coolant temperature sender. Tighten it to 8-15 lb.ft. (10-20 N-m).

11. Connect the upper radiator hose.

12. Fill (top off) the coolant system with the specified coolant. Refer to the 1989/91 Thunderbird/Cougar Shop Manual, Section 27-01 for the cooling system filling procedure.
13. Start the engine and check for any coolant leaks.

14. If the coolant gauge does not operate correctly, check for other causes that could effect the gauge operation.