Offroad-Express

So I've swapped my open rear diff for a factory vacuum locking diff but am having problems getting the diff to engage/disengage. The diff and solenoids are from a petrol GQ and have been swapped to a diesel.

I have bypassed the solenoids (yep they have a 12v feed) to eliminate them. I've teed into the vacuum post vacuum canister for the diff and have vacuum at the diff.... but possibly not enough. With the vacuum on the 'engage' side of the diaphragm assembly, noting happens (this is with one wheel jacked up) but with a little assistance from the air compressor on the disengage side she locks all good (about 10psi assist) and vice versa when swapped around.

The alternator is a couple of years old at a guess so i'd expect the vacuum supply to be all good, also brakes are fine so no obvious red flags there.

Any suggestions?

Cheers

Do you have two vacuum cans and non return valves in the system

Nope....

Which lines require the check valves Coxsy? Where they tee of to either vacuum can from the alternator or on each line to the diff?

Cheers for the heads up by the way.

this is non return valve from main vac feed

twin vac tanks for diff lock

Cheers for the pics Coxsy! Yip ive got that non return valve in place and made a second vac can out of 80mm waste pipe and end caps. Diff seems to lock fine now but the solenoids may need replacing or the wiring looked at as it won't switch on or off, have to do the hose swap for any change.

have you got nissan solinoids if so they maybe faulting after 25 years. Mac valves do a 12v or 24v replacement ones and its a single valve not two

Yip original solenoids so I will look into mac valve - I've only read good things about them. Have you just got one non return valve in the system before it tees of to either vac can?
Cheers.

Yes it's on the main feed in to the first can

you can always use exaust emissions sytem solenoids for replacement by the looks of them they are identical to locker soleniods