Hubs

Hi again, 

In the hunt to remedy my 4x4 problem (light comes on but doesn’t engage the hubs) I can’t find a leak in the lines. 

I have removed the hubs and taken some pics, is there anything obviously wrong, missing or heavily worn? 

I know I can change them out for manual but I’d like to have the problem fixed. Before resorting to that. Call it ocd in today’s society. 

EDIT: I forgot to say- the pictures look ok to me. If you poke your finger inside the hub, the internally splined part will move with a bit of effort and snap outwards into 4WD and inwards into 2WD. You will see the big teeth engage something when it is in 4WD, and you can't turn the internal splined part, in 2WD the internal splined part can rotate relative to the hub. There are magnets holding it at the end positions that you have to overcome to move it over.

Do the hubs make a noise when you switch to 4WD & 2WD (engine running?) They should go "Clackclack" & "Clickclick".
If they do, the pipes may be crossed over and they engage in 2WD and disengage in 4WD.

Then it is check everything, please yourself where you start.

1) leave the hubs off and whip the wheels off. You should be able to blow through both of the spigot pipes. Fitting new wheel bearings often block one with grease, I think it is the "engage" port.

2) Put the hubs back on and find something that will suck air out of the ports - I have a 100ml syringe that works. Snatch the syringe back and you should be able to hear the hub move, and feel a bit of resistance. If there is no resistance and nothing happens, could be wheel bearings or seals gone.
(In theory, blowing into the other port at around 10 psi max should move the hub, but vacuuming them is best as that is how it is supposed to work and the seals are working the right way.)

3) check the blue non-return valve in the vacuum line to the inlet manifold. you can suck through it from the engine side, but not the tank side.

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.

My problem was leakage between ports A & C when off, so the tank never built up any vacuum and the hubs wouldn't move I fixed it by squirting GT85 into the ports and operating the solenoid loads of times. They go sticky if someone drives through water and it gets into the vacuum lines either through the hub seals or more likely that little air filter.

Obviously check that all the rubber pipes connect to the solenoid valves.

4) Remember that 100ml syringe?  pull it out and attach it to either of the vacuum lines that went to one of the hubs (make sure the other side hub lines are connected) switch to 4WD & 2WD (engine running). The syringe should have pulled right back in if the vacuum lines & valves are working.
Repeat for the other line. For completeness, you might as well repeat on the other side (reconnect this hub first).

That should find your problem, then you just have to figure out which line goes to which spigot on the hub, and get them both the right way round!



 

Thank you for such a thorough reply. No noise when I engage them or disengage.

I have a 4WD light on.

I have jacked it up and both front wheels rotate when in 2w and when in 4WD.

The little “filter” next to the solenoid had virtually no filter in it I’ve whipped that off and put some sponge in it for now.

The solenoid looks filthy if I disconnect it and break it (ham fisted) I’m guessing I just buy another?

I have some time tomorrow afternoon but need the car at the weekend. If I break the solenoid is the car drivable?

facade wrote:

1) leave the hubs off and whip the wheels off. You should be able to blow through both of the spigot pipes. Fitting new wheel bearings often block one with grease, I think it is the "engage" port.

2) Put the hubs back on and find something that will suck air out of the ports - I have a 100ml syringe that works. Snatch the syringe back and you should be able to hear the hub move, and feel a bit of resistance. If there is no resistance and nothing happens, could be wheel bearings or seals gone.
(In theory, blowing into the other port at around 10 psi max should move the hub, but vacuuming them is best as that is how it is supposed to work and the seals are working the right way.)

3) check the blue non-return valve in the vacuum line to the inlet manifold. you can suck through it from the engine side, but not the tank side.

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.

My problem was leakage between ports A & C when off, so the tank never built up any vacuum and the hubs wouldn't move I fixed it by squirting GT85 into the ports and operating the solenoid loads of times. They go sticky if someone drives through water and it gets into the vacuum lines either through the hub seals or more likely that little air filter.

Obviously check that all the rubber pipes connect to the solenoid valves.

4) Remember that 100ml syringe?  pull it out and attach it to either of the vacuum lines that went to one of the hubs (make sure the other side hub lines are connected) switch to 4WD & 2WD (engine running). The syringe should have pulled right back in if the vacuum lines & valves are working.
Repeat for the other line. For completeness, you might as well repeat on the other side (reconnect this hub first).

That should find your problem, then you just have to figure out which line goes to which spigot on the hub, and get them both the right way round!




 

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

Yes, the car is driveable in 2WD, just block the pipe to the manifold so there is no air leak into the manifold to upset the idle.

There is a vacuum switch on the line to the engage ports, when you engage 4WD the solenoid valves do their thing and apply vacuum to the engage line. If a vacuum builds up the switch triggers and it thinks 4WD has engaged (it just assumes that with no leaks everything moves as it should) so the green light comes on steady.

With no vacuum in the tank, the hubs can't move, and that switch can't switch, and the 4WD controller flashes all sorts of lights, and won't go into low IIRC, but will engage 4WD and the green light flashes (I think, my Gen 3 had a lever transfer)


At a guess, your problem will be no vacuum in the tank, probably due to leaking solenoid valves.

My old Gen 3 had the same as yours, a solid green light on, but the hubs didn't move.

In my case it was the complicated arrangement of metal and flexible tubing from the solenoid valves to the hubs which was both broken and blocked, hence I got a vacuum. After messing with it for a couple of days one winter, I fitted manual hubs and never had another problem.

However, when I came to sell it, the buyer wanted it standard, so I bought some plastic pipe and routed new flexible pipe all the way from the solenoid valves to the hubs, it worked first time and was very reliable.

Robin

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.