A/T - ATF Loss From Housing Vent
88porsche01Subject: ATF Loss From Vent of
Automatic Transmission
Model
924S - 944
Group
3
Part Identifier
3860
Number
8808
April 1, 1988
The following parts and procedures have been developed to reduce the chance of ATF loss from the automatic transmission housing vent. A temperature switch installed in the automatic transmission cooling circuit at the radiator closes at approximately 87~C (189~F) causing the engine cooling fans to run at maximum speed to reduce the temperature of the ATF. The cooling fans operate independently of engine coolant temperature when activated by high ATF temperature.
FIGURE 1:
Parts kit required for service installation (See Fig. 1) PN 000 043 106 00 includes:
1 - Temperature switch PN 928 606 217 00
2 - Switch Adapter
3 - Hollow Bolt
4 - Sealing Rings PN 013. 814.8
Note: The cable harness (5) is not supplied in the Parts Kit and, therefore, must be made locally to the following specification:
FIGURE 2:
2 lengths of 0.5 mm x 1440 mm electrical wire
1 length 1300 mm of wire covering for the above wiring. (electrical tape can be used)
4 Electrical connections PN 999 652 113 10
4 Connector boots PN 311 971 867 A
Note: When assembling the wire harness, leave approximately 70 mm of free wire at both ends of harness. In addition, attach 2 connector boots and electrical connectors on one end of the harness only. The remaining connectors will be attached later. (see Fig. 2)
Installation Procedure:
Temperature switch installation:
1. Remove lower engine cover and drain engine coolant and radiator.
2. Remove lower radiator hose from radiator. Catch residual antifreeze in a drain pan.
3. Remove the hollow bolt for the lower ATF cooling hose. Caution! To avoid damage to the radiator, counter-hold the radiator fitting adapter.
FIGURE 4:
4. Install the temperature switch into the switch adapter and torque to 30 N-m (22 ft.lbs.). Pre-assemble the switch adapter along with the new hollow bolt and sealing rings onto ATF line and install onto radiator. Position the temperature switch as shown in Fig. 4. Tighten the entire assembly to 30 N-m (22 ft.lbs.). Be sure to counterhold the radiator fitting adapter.
5. Reinstall the lower radiator hose and tighten clamp.
6. Connect the locally made wiring harness to the temperature switch.
Route the harness to the left under the cooling fans.
FIGURE 9:
Note: On 944 with air conditioning, route the end of the harness to the area of the high pressure switch on the receiver dryer. On 944 without air conditioning and all 924S, route the harness to the radiator fan switch at the left upper area of the radiator.
Note: Refer to included wiring diagram
7. Disconnect the existing wires from the connecting point on 944 with air conditioning or from the radiator fan switch (944 without air conditioning and all 924S) and cut the connectors off. Remove the existing connector boots and discard.
8. Connect one wire from the ATF temperature switch harness to one wire to the radiator fan switch or the high pressure switch. Repeat the procedure for the remaining wire. Install the connector boots over the joined wires and crimp the remaining two connectors onto the wires.
Reconnect the wires to the high pressure switch or to the radiator fan switch (depending on model type and equipment). Properly secure wires with tie wraps.
Refill the cooling system and bleed free of air. (Refer to 944 Workshop Manual Vol. 1, Page 19-1.)
Reinstall lower engine cover.
Test drive and check for leaks and proper ATF and coolant levels.