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Massey Ferguson 7620, 7622 Removing and install the cover plate and charge pump

MF 7400-7700 Series Tractors Repair Operations

Removing and install the left-hand cover plate

Removal

Immobilise the MF 7620, 7622 tractor. Chock the right-hand rear wheel.
Chock between the frame and the front axle (optional). Partially drain the housings.

Remove:

- the rear left-hand wheel and Install a safety stand underneath the trumpet housing
- the fuel tank, having partially drained it beforehand.

Unscrew the strainer bowl (20). Remove the strainer (6).

Remove:

- screws (10) and (19);
- the nuts (28).

Release and remove the cover plate.

Reinstall

Clean the mating faces of the housing and cover plate. Smear the mating face of the cover plate on the housing with Loctite 5206 or equivalent.

Replace the "O" ring providing the seal between the charge pump and charge pipe.

Fix the adhesive face of the flat seal to the suction manifold. Figurs shows a flat seal adhered to a suction manifold for a Massey Ferguson 7622, 7620 GPA40 rear axle.

Check:

- that the two locating pins are on the cover plate;
- that the GPA40 rear axle charge pipe is correctly positioned. The charge pipe is fixed to the inside of the centre housing by a clip.

Screw two locally obtained guide studs into opposing holes on the centre housing or the intermediate housing (depending on assembly).

Slide the cover plate (14) onto the two studs mentioned above, aligning the studs (7) with the relevant ports on the cover plate.

When the end of the studs (7) protrudes beyond the external face of the cover plate, gradually and partially screw on the nuts (28).

Using a plastic hammer, strike the cover plate to move it towards the housing. Remove the locally obtained guide studs. Use the screws (10) and (19) to definitively attach the cover plate to the housing.

Tighten opposing screws (10) and (19) to a torque of 90 - 120 Nm. Unscrew the nuts (28). Lightly smear their thread with Loctite 242 or equivalent. Lock them definitively at 15 - 20 Nm.

If necessary, replace the "O" ring (21) on the strainer bowl (20). Position the strainer (6). Tighten the bowl to a torque of 15 - 20 Nm.

Reinstall the fuel tank and pour any drained fuel back in. Install the wheel and tighten the screws or wheel nuts to the correct torque depending on the version. Top up the oil level in the housings.

Check it:

- for GPA20, using the gauge located to the right of the PTO housing;
- for GPA30, on the sight glass on the left-hand side of the centre housing;
- for GPA40, using the sight glass located to the left of the PTO housing;

Carry out a road test. Check the tightness of the mating face of the cover plate and strainer bowl (20).

Removing and install the charge pump

Take off the cover plate.

Removal

If the gear is also to be removed, immobilize the gear and unscrew the nut while the charge pump is on the cover plate.

Using a puller, release the gear (if required). Unscrew the screws and remove the charge pump (2).

Reinstall

Clean the mating faces of the MF 7622, 7620 charge pump and cover plate. Check the presence of the dowels.

Inside the cover plate, apply a bead C of Loctite 574 or equivalent around the two charge pump screw holes.

The diameter of the bead should be small so as to not touch the groove of seal. Install a new seal.

Install the key and the gear (if removed) onto the charge pump shaft. Install the charge pump onto the locating pins.

Lightly smear the thread of the screws with Loctite 242 or equivalent. Tighten these screws to a torque of 40-50 Nm. If the gear was removed, lightly smear the thread of the nut with Loctite 242 or equivalent.

Tighten this nut to a torque of 50 - 60 Nm. Manually check the rotation of the charge pump. Install the cover plate.

Replacing the charge pump seals

Remove the Massey Ferguson 7620, 7622 cover plate and the charge pump.

Disassembly

Removal of the charge pump is identical irrespective of the type of rear axle (GPA20, GPA30 or GPA40).
Moderately secure the charge pump in a vice Installed with protective jaws.
Unscrew the screws (1) and remove the cover plate (7).

Remove:

- the circlip (3);
- the seal (4);
- the "O" rings (5) (6) on the cover plate (7).

Reassembly

Carefully fit the seal (4) using a suitable fixture. Lubricate its lip (with miscible grease).

Install the circlip (3). Lightly smear the "O" rings (5) and (6) with miscible grease.

Position these seals in the grooves of the cover plate (7).

Correctly position the cover plate above the charge pump and then Install the cover plate.