Hubs

Busta wrote:

 

That's a great checklist for anyone tracing vacuum faults! Can we add it to the wiki?
 

Sure, if we fix the typos...

I missed a sentence out about using the syringe to apply vacuum and test the hub, obviously you have to connect it to each spigot in turn, and if it doesn't move it may be because you are trying to move it the way it is currently set, so try the other port, if you hear it move, swap back to the original port and it should then move back when you pull.

Right so I had some time yesterday.

Jacked it up removed the hub and wheel disconnected the pipes on both of the spigots on the hub blew through them to make sure they were clear.

Syringed the hubs and got a clack from both sides. Also put the syringe on and engaged 4WD drew the syringe in.

Swapped the pipes over, on the rear of the hub to check if they’d been put on wrong at some point. When I did this as soon as I started the car the hub went clack. On both wheels. Without manually engaging the 4WD. How is there vacuum pressure without engaging?
I swapped them back round.

Momentarily for about 6 times in a row when I engaged 4WD the passenger hub engaged (although not loud enough to hear) and then disengaged when put back into 2WD. When I put the wheel back on the ground to check the other side it stopped doing it.

Can I rule anything out knowing that they engaged etc?
I couldn’t get the solenoid off to check it.


Checked all the pipes were connected and not cracked.

Weejimmy wrote:

<snip>

Swapped the pipes over, on the rear of the hub to check if they’d been put on wrong at some point. When I did this as soon as I started the car the hub went clack. On both wheels. Without manually engaging the 4WD. How is there vacuum pressure without engaging?

<Snip>

Can I rule anything out knowing that they engaged etc?
I couldn’t get the solenoid off to check it.


Checked all the pipes were connected and not cracked.

 

There is a vacuum leak through the solenoid valve that disengages the hubs. (Port B to C in my notation, see diagram)
Either it leaks all the time, and the vacuum tank gradually loses vacuum, which would mean the engine vacuum has to operate the hub directly, or there is a wiring fault (or a piping fault somehow, but I doubt it unless someone has messed around with the solenoid valves.)

With vacuum on the disengage side permanently, there is nothing (literally) to push the hub over to engage, it is atmospheric pressure on the opposite side through the non-energised solenoid valve that moves the hub.

Remember my earlier post?

4) remove the solenoid valves and test them with 12V and blowing through a tube.
There are 3 ports on each,
A) Fresh air (via filter)
B ) vacuum line to hub
C) vacuum line from tank.

Power off:  A connects to B and C is sealed off to maintain vacuum in the tank
Power on: B connects to C and the tank vacuum applies to the hub to move it (A could be sealed but it doesn't matter, and I never tested it) The other solenoid lets air into the other side of the hub via A-B to push the hub over.

Here is the diagram from the manual, suitably annotated to match my description

 



This is what the layout looks like


 


Photograph where the pipes go, pull the solenoids, squirt GT85 (or your favourite magic fluid) into the ports and cycle the solenoid a few dozen times with a suitable 12V supply (be careful of shorts if you are going to use a car battery!)
Then check that
Power off- Port C is sealed A connects to B
Power on- port C connects to B and absolutely not to A as well.

 

Thanks again for your reply. Do I just unbolt the whole solenoid pack or can I unclip them assuming at the red top to remove them?

I did attempt to undo the bolt to remove the whole thing but couldn’t get the bolt loose.

On my 2001 they came off as the pair bolted to a metal plate, I didn't need to disturb them.