Bleeding diff locks?!!

Hello Bill,

Would you please mention which is your chassis type? W460, 461 or 463?

Cheers,

Hi Bill,

Thank you for your reply, but it is the first three digits of the chassis number I want, please.

You can find this on the chassis plate on the vent housing, when you lift your bonnet or it will be stamped on the front part of the chassis its self, looking form the wheel arch.  This can be stamped either on the left or right side, depending on model.

Regards,

Hello Bill,

Vehicle orientation, definition:
Left or Right side, is, as observed from the rear of the vehicle, viewing forwards.
Near-side or Off-side definitions will not be used, as the reader or article written, could be from the European mainland.

Bleeding W460 front and rear diff locks.

Firstly, check the fluid reservoir for the diff. locks (d/ l). This is mounted on the left-side (l/s) of the vehicle; under the bonnet. The reservoir is small and round. It is to be found in front of the Battery (RHD vehicles’) and close to where the shock absorber mount is.  There should be brake fluid in it, if not, expect to looking for a leak, probably due to a perished rubber hose(s).
Tracing the path down from the reservoir there should be an “F” plastic fitting, connecting to the two hydraulic cylinders. These cylinders activate the front and rear diff. lock cylinders. Brake fluid from the reservoir is commonly fed and the “F” fitting splits the feed to each hydraulic cylinder. There is a pull/push lever connected to these cylinders, that when pulled, from within the cab; the activated cylinder will transmit its hydraulic force to the diff locks.

There is rubber hose to and from the “F” fitting; these are susceptible to being perished, check their condition and replace as necessary. Do check the bleed screw(s) (b/s) is not blocked up, clear as necessary.

The most effective way to bleed the system(s) is by a vacuum bleeding the system or gravity bleeding (very slow and not quite effective). There is a pressure bleed method but it all boils down to what equipment you have at hand.

To vacuum bleed, Pull the diff lock plunger and suck the brake fluid through from the b/s found at the diff lock cylinder. This must be done for each cylinder, front and rear. Suck until clear fluid bleeds through and having achieved this, close off the b/s.

If you have those eazi-bleed kits from accessory shops, you may use it to attach to the reservoir cap and use a spare tyre pressure (tyre pressure set at 20 psi) to assist in bleeding by the b/s at the diff. lock cylinder.
Not having any such equipment, two people will be required for the next operation. One person to crack open the b/s initially, followed by the second to pull the plunger, making sure the correct plunger is worked in relation to the bleed screw opened. The front plunger should operate the front diff. lock conversely; the rear plunger works the rear diff lock.

After the plunger has been pulled, a kin to depressing the brake pedal in brake bleeding; the b/s operator needs to close off the b/s. The plunger operator should push down on the plunger, the b/s operator to crack open the b/s followed by the plunger operator to pull up again. This has to be repeated again and again until clear fluid bleeds through, not having any air bubbles in the system at all.

Failing this, hand the job over to a professional garage.

Late entry:

I had forgotten to mention that the fluid level in the reservoir, whilst bleeding, needs to be kept topped up.  Any air leak at this stage will only put you back.  So after every bleed, top up the reservoir, since it is only a small pot.

The other point, I should have mentioned; because I can not remember, if the hydraulic cylinder with the plunger lever has b/s, firstly bleed at that point  applying the same principle described above.  Bleeding the cylinder, with clear fluid flowing, then move on to the diff. lock cylinders.
 
Regards,

I think I just used time and gravity to bleed mine.. open bleed screws and fill reservoir. Then wait.. gravity will cause the fluid to drain downwarded.s enough to get it semi bled. Now close bleed screws and open them a very small amount.. about 1/16 to 1/8 of turn. Now you can "pressure bleed" them in a different manner to that described. Basically you pump using the levers as fast and hard as you can.. and when it stops pushing out foamy fluid at bleed screws it is bled. This works with most brakes too. The "pressure bleeding" works as if you pump faster than the small hole left by the very nearly closed bleed screw you pressurise the fluid and it is squirted with foamed/trapped air. The other methods work too..

                
                                                                      Bon voiyage!