Still no 4wd... any suggestions please

Hi guys, I've recently purchased a 2009 Jimny. I've done alot of work on the car already and solved alot of issues, but for the life of me I cant get the 4wd to work. I'm hoping someone might be able to help. its a complicated one.

All the buttons for 4wd and 4wd_L work fine, they both select on the dash as they should. 
When pressing the 4wd buttons I can hear the "click" of the hubs - all good signs.

But no 4wd...

After some routing around I found that all the vacuum pipes on the drivers side were completely rotten through, and some suspect ones on the passenger side. So I've replaced all of those using silicone boost pipe. 

This made no difference, all the buttons and lights on the dash are fine, and I can still hear the clicking of the vac hubs.

So then I'm thinking, perhaps its a front CV thats gone, so I stripped down both front hubs and removed both driveshafts and CVs, on inspection both CVs and shafts are in perfect condition, so I cleaned them, re-greased and put it back together.

When I jack the car up one front wheel at a time, with 4wd selected both front wheels can easily spin freely by hand, so its not engaging somewhere.
I've had the car up on 4 axle stands and had it in 4wd and in gear, again no drive to the front wheels, but the centre prop does engage and disengage when coming in and out of 4wd.
 
Would this point to a knackered front driff?

or have I missed something.

Any help is appreciated.
Cheers,
James.

What are you describing as the "center prop"?

There should be three "propeller shafts" - a short jack shaft between the transmission (gearbox) and the transfer case and two longer ones from the transfer case to the axles.

Since you have the facility to run the vehicle with all four wheels off the ground, I would suggest you remove the front hubs so you can see the ends of the front half shafts and then run the vehicle in 4H - if the half shafts turn you're probably good from the transfer case all the way out to the hubs.

Put in in 4wd then remove both hubs and check the position of the sliding collars. Both should be in the inwards position, e.g. closest to the centre of the axle if they were fitted to the car. You need both hubs to be engaged to get drive to the front wheels.
I would be very surprised if the diff has failed without giving away some clues such as horrible noises or lumps of metal in the oil. Have you drained the oil?

Sorry I wasn't very clear. The prop that goes to the front diff spins when 4wd is engaged.

thanks

That's fantastic advice thank you. This will be my next port of call. I need to double check the lines on the passenger side, it could well be that they have suffered from rust too.

And yes, there no noises or anything from the front diff at all, no drained the oil yet.

I'll double check the sliding collars and all the vac lines again.

Many thanks

I had a very similar problem some time ago and found one of the vacuum hubs was faulty which is easy to check by engaging the 4wd and taking off the hubs to see which is engaging.
bryn

Thanks everyone, I think we have found the problem. There must be something still not working with the vac system. I put the car into 4wd and remove the vac hub, both hubs were in the 2wd position (away from the car).

When i manually wiggle the splined centre of the vacuum caps, they shoot out into the 4wd position, they seems to shoot out with some "pop" so I think those are working fine. I'll go over the pipes with a fine toothcomb this weekend.

thanks all.

Thanks all for the help

It seems someone has tricked the system into thinking everything is working correctly then. You may find a 2 wire electrical connector below the battery that has been tampered with. I believe it's white or has white wires.
The best fix I've found for the vacuum pipes is to buy 10m of 4mm id PVC hose (about £6 on ebay) and replace the whole lot. I routed mine around the engine bay and down the brake hoses to the hubs. It's much less vulnerable there than it is running along the radius arm and axle. 

Damn! I hate it when people don't do things properly!
I'll check that thank you!

Yes, I have loads of silicone vac hose, so I'll replace all of the other side too.

Hi guys, finally all fixed and 4wd working a charm. I wanted to update this thread incase it helps others in the future.

I replaced all the remaining hoses with silicone boost pipe, and then set about fault finding one by one.

So firstly I removed both vacuum hub and had the car sat on 4 axle stands. With the hubs off and 4wd selected I could see the front driveshafts spinning - This is great, as it meant all the mechanical bits and bobs were working as they should.

This then pointed to something wrong with the vac system or the hubs. I check the hubs by hand, cleaned and regressed them, so I knew they were in good order.

With 4wd selected I manually put the hubs into 4wd, refitted them and started the car in gear, the front wheels span for about 5 seconds before stopping. This seemed very odd, why were the hubs being puled out of 4wd?!

I set up my airline with some of the vac hose on the end and blew out each vac inlet into the hub, again I manually selected 4wd by blowing the airline down the hole to the side of the hubs. refitted the hoses and the same thing happened, it would pop back out of 4wd on its own accord.

I double checked the vac lines again, something was a miss. The hoses surely couldnt be the wrong way around could they!? as one is shorter than the other... I switched the vac hoses around and bingo... we have 4wd.

So I can only think a previous owner has been trying to get it working and for some reason they must have switched the hoses further down the lines...

So to summarise, the lights on the dash were working fine because the vac system was actually working perfectly.

A lot of hassle but determination paid off.

always great seeing feedback after issue was resolved

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