Automatic Transmission/transaxle: Maintenance Jaguar XJ X351

FLUID PUMP

The fluid pump is an integral part of the transmission. The fluid pump is used to supply hydraulic pressure for the operation of the control valves and clutches, to pass the fluid through the transmission cooler and to lubricate the gears and shafts.

The ZF 6HP28 fluid pump is a crescent type pump and is located between the intermediate plate and the torque converter. The pump has a delivery rate of 16 cm 3 per revolution.

The pump comprises a housing, a crescent spacer, an impeller and a ring gear. The housing has inlet and outlet ports to direct flow and is located in the intermediate plate by a centering pin. The pump action is achieved by the impeller, ring gear and crescent spacer.

The crescent spacer is fixed in its position by a pin and is located between the ring gear and the impeller. The impeller is driven by drive from the torque converter hub which is located on a needle roller bearing in the pump housing. The impeller teeth mesh with those of the ring gear. When the impeller is rotated, the motion is transferred to the ring gear which rotates in the same direction.

The rotational motion of the ring gear and the impeller collects fluid from the intake port in the spaces between the teeth. When the teeth reach the crescent spacer, the oil is trapped in the spaces between the teeth and is carried with the rotation of the gears. The spacer tapers near the outlet port. This reduces the space between the gear teeth causing a build up of fluid pressure as the oil reaches the outlet port. When the teeth pass the end of the spacer the pressurized fluid is released into the outlet port.

The fluid emerging from the outlet port is passed through the fluid pressure control valve. At high operating speeds the pressure control valve maintains the output pressure to the gearbox at a predetermined maximum level. Excess fluid is relieved from the pressure control valve and is directed, via the main pressure valve in the valve block, back to the pump inlet port. This provides a pressurized feed to the pump inlet which prevents cavitation and reduces pump noise.

FLUID LEVEL AND CONDITION CHECK

Note. The transmission fluid temperature must not be allowed to exceed 50°C (122°F) whilst checking level. Should the temperature rise above this figure, abort the check and allow the transmission fluid to cool to below 30°C (86°F).

This vehicle is not equipped with a fluid level indicator. An incorrect level may affect the transmission operation and could result in transmission damage. To correctly check and add fluid to the transmission.

High Fluid Level

A fluid level that is too high may cause the fluid to become aerated due to the churning action of the rotating internal parts. This will cause erratic control pressure, foaming, loss of fluid from the vent tube and possible transmission damage. If an overfill condition is identified, with the engine at idle ensure the fluid temperature is within the specified range and allow the excess fluid to drain until a small thread of fluid runs from the filler/level plug hole.

Low Fluid Level

A low fluid level could result in poor transmission engagement, slipping, or damage. This could also indicate a leak in one of the transmission seals or gaskets.

Adding Fluid

If fluid needs to be added, add fluid in 0.50 liter increments through the fill hole Opening. Do not overfill the fluid. For fluid type, refer to the General Specification chart in this section.

Fluid Condition Check

1. Check the fluid level.
2. Observe the color and the odor of the fluid. The color under normal circumstances should be Honey.
3. Allow the fluid to drip onto a facial tissue and examine the stain.
4. If evidence of solid material is found, the transmission fluid pan should be removed for further inspection.

Note. In the event of a transmission unit replacement for internal failure, the oil cooler and pipes must also be replaced.

TRANSMISSION FLUID LEVEL CHECK

Special Tool(s)

307-452 Wrench, Transmission Filler Plug

TRANSMISSION FLUID DRAIN AND REFILL

Special Tool(s)

307-452 Wrench, Transmission Filler Plug

Note. Some variation in the illustrations may occur, but the essential information is always correct.

Scheme 44

1. Raise and support the vehicle.
2. Refer to «Air Deflector»(ref-570100-S33802335332013080600000) information.
3. Place a container under the transmission.
4. Wrench, Transmission Filler Plug (307-452)
5. Allow the fluid to drain. Discard the component.
6. Torque: 8 Nm
7. Refill the transmission with fluid.
8. Allow the transmission fluid to drain from the transmission fluid filler plug hole until the flow almost stops.
9. Loosely install the transmission fluid fill plug.
10. To make sure the transmission fill plug is torqued to the correct specification. Using the special tool and torque wrench the following calculation steps must be followed. Step 1. Multiply 35 Nm by the effective length of the torque wrench (1). Step 2. Add the effective length of the special tool (2) to the effective length of the torque wrench (1). Step 3. Divide the total of step 1 by the total of step 2. Step 4. Set the torque wrench to the figure arrived at in step 3. Tighten the transmission fluid fill plug to the torque given by the calculation.
11. Carry out a transmission fluid level check. Refer to «Transmission Fluid Level Check»(ref-570091-S01044122382013080600000) . .
12. Refer to «Air Deflector»(ref-570100-S33802335332013080600000) information.
13. Lower the vehicle.