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Vacuum hubs
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Author:  zooky08 [ Mon Sep 26, 2011 9:58 pm ]
Post subject:  Vacuum hubs
Okay so I've found I don't have 4wd in my Jimny
I've check the lines going to my hub and found

Right side hose to diff:
2wd doesn't suck/vacuum
4h sucks/vacuum
4l sucks/vacuum

Left side hose to diff:
2wd sucks/vacuum(can hear left hub lock)
4h doesn't suck/vacuum
4l doesnt suck/vacuum

I don't know much about vacuum hubs on a Jimny but I would think they they both should be the same. Not different
Author:  Bombero [ Mon Sep 26, 2011 10:44 pm ]
Post subject:  Re: Vacuum hubs
There are two hoses that go to the diff swap them over on the left side and bobs your aunti.
Author:  zooky08 [ Tue Sep 27, 2011 12:24 am ]
Post subject:  Re: Vacuum hubs
Bombero wrote:
There are two hoses that go to the diff swap them over on the left side and bobs your aunti.
that has fixed the light but still doesn't lock my hubs.
Author:  zooky08 [ Tue Sep 27, 2011 2:13 am ]
Post subject:  Re: Vacuum hubs
Another thing is that the hoses loose there vacuum after a few seconds.
Author:  gman [ Tue Sep 27, 2011 2:47 am ]
Post subject:  Re: Vacuum hubs
Check right hand hub make sure the locking collar isn't full water and shit or there is a slight leak some where sometimes the locking solenoid can not close properly as its vent isn't filtered very well when locking or unlocking vaccum is applied to the appropreate vacumm circuit only for 20 or 30 seconds not sure exactly if the vacumm doesn't build enough it will trigger a sensor and the 4wd light will flash i'd look for asmall leak somewhere on locking circuit
Author:  zooky08 [ Tue Sep 27, 2011 3:37 am ]
Post subject:  Re: Vacuum hubs
I had a look for leaks but couldn't see any. Ill give it another shot and see if I can work it out.

My front drive shaft does rotate so can't be transfercase.
Btw forgot to ment this is a 03 model so has stick case not button if that makes any difference?
Author:  Moag [ Tue Sep 27, 2011 11:22 am ]
Post subject:  Re: Vacuum hubs
My guess is that your got a small vacuum leak on the right side vacuum hard pipe/hose or the hub is sticking or has vacuum leak.

Some pictures to help with fault finding, so your got a better idea as to how it works.

Image

Image

Image

When I brought my Jimny it had no hubs engaging with flashing 4X4 light when 4X4 engaged.
The main problem was the flexible vacuum hoses where they join the leading arms.
One was ripped off and the other was worn to the shit house.
Replaced those but VSV2 was stuffed - more then likely because of all the dust it had been sucking.

Bush fix was to run a long vacuum hose and bypass VSV2 to lock hubs and then
alternatively bypass VSV1 to take the hubs out.

Pain in the ass but worked. Plus hint as to how you may be able to fault find.

In the end I just got manual hubs. :lol:
Author:  zooky08 [ Tue Sep 27, 2011 11:31 am ]
Post subject:  Re: Vacuum hubs
Thank you very much moag I'll give that a try.
I'm so tempting to put manual hubs on.
As far as I see vacuum hubs are asking for trouble.
Author:  gman [ Tue Sep 27, 2011 11:42 am ]
Post subject:  Re: Vacuum hubs
Good stuff moag, that's exactly what I wanted to post but couldn't find. I have to say anyone with a newish jimny should run breather lines from the exhaust side of vsv1 and vsv2 to the filtered side of the air filter box. In my experience, apart from vacuum line damage dirt in vsv1 and 2 can,be a common cause of hub failure. wish I did it years ago 225000kms on my Jim now heaps of offroad and vacuum hubs still operational not without plenty of attention
Author:  zooky08 [ Tue Sep 27, 2011 11:50 am ]
Post subject:  Re: Vacuum hubs
The little airfilter thing is bit dirty. Would that course my problem.
Would pulling one hose off at a time and blowing them out to see if there any blockages help.
If that doesn't work then I'll pull the hubs of and check them out
Author:  Moag [ Tue Sep 27, 2011 12:15 pm ]
Post subject:  Re: Vacuum hubs
[quote="zooky08"]The little airfilter thing is bit dirty. Would that course my problem.

Maybe, all that dust may end up in your engine.

Would pulling one hose off at a time and blowing them out to see if there any blockages help.

Yes but I would start below VSV2 back too the hubs, focusing on the right side branch. But you need to find any small vacuum leaks./i]


If that doesn't work then I'll pull the hubs of and check them out

[i] Firstly - There is two little pipes coming out of the back of the hubs.
Run a vacuum hose from the inlet manifold directly to each one in turn to see/hear if the hubs are engaging. If they do they're ok; if not I'm lost. Pulling the hubs to bits is the last resort/quote]
Author:  gman [ Tue Sep 27, 2011 12:24 pm ]
Post subject:  Re: Vacuum hubs
Shit that the little filter doesn't catch is sucked into the solenoid along with water from puddles washing etc internals of solenoid start to rust and stop sealing when closed. Not sure if this could work but shift car into 4wd listen for both hubs to click, you said only one is clicking atm, so immediately after shifting transfer get the garden hose and hose different parts of the system (vacuum lines, the hub, solenoids,) anywhere there could be leak. Hopefully, the water will restrict the leak and the non locking hub will engage this may help you find the leak (maybe) just remember the 4wd module will only apply vacuum for a matter of seconds than vacuum will be released from system, select 2wd, than back to 4wd and try another spot with hose. Once you hear the second hub lock than the leak should be in the area your covering with water while it locks.
Author:  gman [ Tue Sep 27, 2011 12:27 pm ]
Post subject:  Re: Vacuum hubs
The hubs arn't complex just a locking collar and magnet inside
Author:  smiffkid [ Tue Sep 27, 2011 12:27 pm ]
Post subject:  Re: Vacuum hubs
my vacum hubs stopped leakin cause they got a bit of dirty water in them
so they came off in exchange for a set of avms
work every time
Author:  gman [ Tue Sep 27, 2011 12:33 pm ]
Post subject:  Re: Vacuum hubs
So do my auto hubs now, and I don't have to get out or stop to engage 4wd, I like the sound of the hubs locking by themselves too :)
Author:  zooky08 [ Tue Sep 27, 2011 12:35 pm ]
Post subject:  Re: Vacuum hubs
So many ideas I will try them tomorrow.
Well not sure but I was under the car and I thought it was the left hub locking. When I was in the car I can hear a hub locking not sure with one to be exact.

The hoses do loose vacuum after a few seconds
Author:  smiffkid [ Tue Sep 27, 2011 12:40 pm ]
Post subject:  Re: Vacuum hubs
it is good to change while still in the car
but at least i know there gonna last a few water crossings and not disengage when in reverse like my ol 1s did under pressure
Author:  Moag [ Tue Sep 27, 2011 1:23 pm ]
Post subject:  Re: Vacuum hubs
Image

Image

Let us now if you find the problem.
Author:  zooky08 [ Tue Sep 27, 2011 1:39 pm ]
Post subject:  Re: Vacuum hubs
The flexible hose are all good, very tight fit onto hardline.
No splits or any thing. I'll check hardlines tomorrow, I'll try cover all the basic and see if I can find the problem
Author:  steak_knife [ Wed Sep 28, 2011 7:31 am ]
Post subject:  Re: Vacuum hubs
gman wrote:
So do my auto hubs now, and I don't have to get out or stop to engage 4wd, I like the sound of the hubs locking by themselves too :)


So you don't air down????? :?
Author:  zooky08 [ Wed Sep 28, 2011 8:35 am ]
Post subject:  Re: Vacuum hubs
So I found that the right hub will not lock at all by using vacuum, only compressed air locks it. Nothing locks the left side so will have to pull the hub apart. If there vacuum hubs why in the hell will compressed air only lock the hub.
Author:  Moag [ Wed Sep 28, 2011 9:58 am ]
Post subject:  Re: Vacuum hubs
Not looking good for air hubs.

Tried to find my old hubs to have a look, but no joy!!

This is how the manual tests them.

Image

Image

One last test that i can think off is.

Temporally block both vacuum lines where they leave the leading arm.

Start engine and shift it from 2wd to 4x4 and see if the 4x4 light works how it should e.g. Come on when its in 4x4 and goes out in 2wd and there's no flashing when 4x4 is selected.
Author:  zooky08 [ Wed Sep 28, 2011 10:16 am ]
Post subject:  Re: Vacuum hubs
I'll try that tomorrow.
I checked the lines straight from the vsv1 and vsv2 and they work fine. So it's the locking assembly in the hub. I can hear the right hub lock/click but when i go to turn the hub it isnt locked. Puting compressed air in the hub it locks. Put air in the other port and it unlocks. Left hub doesn't do and thing doesn't click or lock. So confusing

So Im gonna pull these hubs apart.
Author:  Moag [ Wed Sep 28, 2011 10:51 am ]
Post subject:  Re: Vacuum hubs
Yes its a bit of a mind fuck but not too much if you simplify the concept.

Just think of the hubs as a tube with a piston in it.
Vacuum on one side pulls it to that side or if your using pressure it pushes it to the opposite side.
Vacuum on the opposite side pulls it that side.

The VSVs are just valves that open or close the vacuum lines using a solinoid.

The solenoids are told to turn on or off by the 4x4 control box(brain) which gets its information from a switch in the transfer box.

There is a vacuum sensor between VSV2 and the hubs, that sends a signal to the control box if a predetermined vacuum is reached, then the control box turns on the 4x4 light.

If there is a leak or not enough vacuum to lock the hubs, the vacuum sensor will fail to send a signal to the 4x4 control box which then makes the 4x4 light flash after tying for 15sec and turn off VSV2.

Clear as mud!!? :blink:
Author:  zooky08 [ Wed Sep 28, 2011 11:05 am ]
Post subject:  Re: Vacuum hubs
That could be my problem. The vacuum is no were near stronger enough to lock the hub. So it makes my light flash.
Author:  Moag [ Wed Sep 28, 2011 11:09 am ]
Post subject:  Re: Vacuum hubs
Thats the next test.

But i thinks your hubs may be fucked or gummed up or leak if they're not working properly.

Edit: Your left hub is the stuffed one!!! the right one may be ok.
Author:  Gromet [ Sat Jan 04, 2014 11:01 pm ]
Post subject:  Re: Vacuum hubs
This is A bit of a thread dig but its the closest i could find to my issue. If I unplug bottom the vacuum hose on the fire wall my hubs lock and unlock perfectly but if i plug it in they only unlock (i need to manual lock them) Ideas?
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