Another 4wd front hub problem/question

Hi there
I have searched quite a few times and found a lot of information on this but am still struggling to get to the bottom of this one.
I bought a Jimny for off road and once off road I discovered that although the 4wd light was coming on and everything I only had rear wheel drive.
I struggled on throughout the day, but now I am on the hunt to fix this problem.
I have found out that it is a problem with the vacuum operated free wheeling front hubs.
I have checked the vacuum supply and the switching and all seems to be ok, but the hubs do not engage.
When 4wd is selected you can hear a 'clunk' from either front hub, but when you check 4wd isn't engaged and when you remove the centre they are not engaged. If you engage them manually (as shown in a guide on here) it seems to work ok, but once you move the selector again if puts them back into free wheeling and they won't lock in again.
I have tried removing the centres and lightly greasing them along with the end of the half shafts, and they worked breifly while the car was jacked up, but then soon stopped working again.
If you have 1 wheel off the floor and spin it by hand, then select 4wd, it breifly stops, but then free wheels once again as if they are trying to engage but stopping.
I tried engaging them and then just disconnecting the vacuum hoses to them (as this Jimny will only do short journeys to go off road) but then the 4wd light wouldn't come on when 4wd was selected.
Does anyone haveany experience of this fault, knows of the solution or can think of any further texts/proceedures I can perform to fix this fault?
Or failing that, is there any way of just engaging them and disabling the vacuum operation of them?

Cheers everyone

you can permanently lock the vacume hubs if needed, heard of people filling them up with silicon to lock them,

other best, safer option is to fit free wheeling hubs with the spacers Martin sells in the shop on this site,

i dont it last year and the 4 wheel drive hasnt let me down once

mlines wrote:

If you want to keep the 4WD light working then block the pipes off up by the solenoids under the bonnet.

Martin

do you have a picture of where to do this?

i get the flashing lights and would like to stop it

I had the same problem mate, I traced all of the air pipes and proved they were clear so mine is blocked where it enters the hub.

Instead of messing about with it i'm on the look out for some freewheeling hubs like the lads have mentioned, it will save messing on with the vacuum.

Its all documented in the How to bit on the home page mate. Its a helpfull little read!!

yeah i've already e-mailed the lad

Cheers for all the replies
Have been out playing around and have manually engaged them. Everything seems to be working fine. Will block the pipes to keep the light from flashing and just leave it like that till I can get some SJ hubs for the near future.
Uber excited about going off road again now, as it was really really hard going in rwd only!