A. Install Bypass Valve (For 3.0L 6-Cylinder Engine)

1. With the ignition off, disconnect the negative battery cable.

NOTE:
To ensure customer satisfaction, remember to record all radio settings before disconnecting the battery and to reset the electronic memory when you have completed the service procedure.

2. Slowly remove the coolant bottle pressure cap to relieve system pressure.





NOTE:
For 1988 MY vehicles, inspect the coolant bottle pressure cap. Replace the cap if it is not a high dome black cap (Figure 1) with stainless steel insert inside the cap (PN 4546111).

3. Drain approximately one half gallon of coolant from the radiator. The drain is located on the lower right rear (engine side) of the radiator.

4. Disconnect the aerator hose from the coolant pressure bottle.

5. Remove the hose clamps from the two heater core nipples.

6. Remove the hoses from the heater core nipples.

NOTE:
Be careful not to break the heater core nipples. To ease removal, slit the hose and peel it away from the nipple. Do not cut the nylon nipple.





7. Cut the left (driver side) heater hose 2-3/4" from the heater core end. Discard the cut off portion (Figure 2).

NOTE:
This is the heater hose which was not connected to the coolant pressure bottle.

8. Cut the right (passenger side) heater hose as follows:





^ For 1988 through early-1991 MY vehicles: Cut the hose 2 up from the pre-formed tee or steel crimp (Figure 3). Discard the cut off section.





^ For 1991 1/4 through 1992 MY vehicles: Cut the hose as close to the bottom of the crimp or collet as possible (Figure 4). Discard the cut off section.

NOTE:
This is the heater hose which was connected to the coolant pressure bottle.

9. Install the two provided 2 3/4" hoses on the heater core nipples using two of the medium sized clamps.

10. For 1988 and 1989 MY vehicles:





^ Disconnect the right wiring harness convolute support clip and cut off the clip (Figure 5).





^ Secure the right side bulkhead connector wiring harness to the left side bulkhead connector wiring harness with the supplied tie strap, to provide clearance for the bypass valve installation (Figure 6).

11. Connect the two plastic nipples of the bypass valve to the heater core using two of the medium sized clamps as follows:





^ For 1988 through early-1991 MY vehicles: Connect Nipple A to the right (passenger side) heater core hose. Connect Nipple B to the left (driver side) heater core hose (Figure 7).

NOTE:
The vacuum motor will be oriented up when correctly installed on 1988 through early-1991 models.





^ For 1991-1/4 through 1992 MY vehicles: Connect Nipple A to the left (driver side) heater core hose. Connect Nipple B to the right (passenger side) heater core hose (Figure 8).

NOTE:
The vacuum motor will be oriented down when correctly installed on 1991-1/4 and 1992 models.





12. Attach the 2 1/4" hose on the nipple of the supplied 900 elbow closest to the small aerator nipple (Figure 9).





13. Install the other elbow nipple into the heater hose which was originally connected to coolant pressure bottle aerator hose such that the small aerator nipple points upward (Figure 10).

NOTE:
Position the clamp away from the accelerator linkage. Aerator nipple must point up to properly bleed coolant system.

14. Attach the elbow/hose assembly to the bypass valve as follows:





^ For 1988 through early-1991 MY vehicles: Connect the elbow/hose assembly to the plastic bypass valve nipple (Figure 11).





^ For 1991 1/4 through 1992 MY vehicles: Connect the elbow/hose assembly to the brass colored bypass valve nipple (Figure 12).

15. Connect remaining heater hose to remaining bypass valve nipple.

16. Connect the supplied aerator hose to the small aerator nipple on the elbow and to the coolant pressure bottle.

NOTE:
For 1991-1/4 and 1992 MY vehicles, cut approximately 3" off the straight section (coolant pressure bottle end) of the aerator hose.








17. Cut a 1" section from the nylon vacuum tubing near the bypass valve and insert the cut ends of the vacuum tubing into the short hoses on the bypass valve vacuum tee (Figures 13 and 14). Secure the vacuum line to the electrical harness with a tie wrap.

NOTE:
There may be two vacuum lines in this area. Cut the vacuum line connecting the manifold vacuum source to the vacuum reservoir. Do not cut the line from the vacuum reservoir to the speed control servo.

18. Install the supplied stand-off clip to separate the heater hoses near the bypass valve.

19. Proceed to Section C.