Vacumm Hubs Just For a Change

2016 car

At 24,000 miles approx it needed new king pin bearings otherwise no issues now 30,000 miles.

On Thursday evening coming up our track it was a bit muddy with snow on the ground and the back end was moving about, went into 4WD and the back end behaved its self.

On Friday afternoon visited a friend and the car was parked down a snowey hill. I reversed it up the hill and the back wheels were spinning and 4WD made no difference, the back wheels were still spinning.

We towed it up the hill. Best guess it was not going into 4WD but the green 4WD light was on and not flashing!!!!!!!!!!!!

Put the car on the two post lift today and lifted it just off the ground.

Started the car put it in gear and the back wheels are going round.

Click into 4WD and the offside front wheel spins slowly and nothing from the nearside front wheel!!!!!!!!!!!!!! You could stop the offside wheel with no issue.

I decided it was the nearside freewheeling hubs faulty!

Removed both vacuum hubs and changed from side to side, both looked good and the same issue no drive to the nearside.

Removed nearside wheel and caliper to get into the two metal vacuum pipes on the back of the hub. The top one was clean, the lower metal tube was full of clean grease. Used a wire to remove the grease.

Put everything back together and have 4WD now.

At the MOT in early November, I got an advisory that the front nearside brake was slightly binding, but taking temperature readings after a no braking run shows say offside front disc brakes 16C and nearside front discs say 20C.

Not an issue thinks I!

We know an overheating disc brake causes the bearing to loose grease and that stops the vacuum from lasting in the hubs. From our 2007 to 2016 Jimny.

I wonder if the grease at the lower metal vacuum tube is the start of a failing nearside wheel bearing from the slight brake binding reported on the MOT. No issue at all when you spin the bearing.



 

Just wondering if I used too much grease when I did the kingpin bearings?

It's very common for people to use too much grease when doing the kingpins! If you put excess grease on the stubby CV shaft then that would be very likely to end up in the vacuum hose that locks the hubs, as the "lock" vacuum path is through the inside of the spindle where the shaft goes. Grease from a wheel bearing failing would sooner find its way into the unlock hose.
However, it is my understanding that the unlock hose is the lower one, on the front of the hub, which sounds like the one you had to clean? Obviously it's a 2 way system so if either pipe is blocked it will have an affect on the operation of the hubs, but that does mean the wheel bearing is more likely to be the source of the grease. Have you ever removed the wheel bearing?

I replaced both wheel bearings on our 2007 to 2016 Jimny. I have never replaced the wheel bearing on this car I do have the fancy wheel bearing bolt spanner and a 12 tonne press so not an issue if it needs changed.

I used the black waterproof grease that Martin recommends for the king pin job. The grease today was a clean straw colour so that is tending towards wheel bearing grease.

Mine has failed to engage 4x4 for the first time yesterday. Right side is waiting for new bearings has a leaky inner seal so the grease is full of oil. Left side is newly done. Too cold now with minus 15 to do the right side but I suspect the icy conditions has made any water ingress freeze.
Had the same problems with the maunal hubs in sub zero conditions with old grease, could not turn them. but those days I used to flip the over to locked at the beginning of winter and they stayed there until spring.
At first they engaged after a while of a period of alot of blinking and not so much 4x4 engiging or disengaging until they finally made it.
Now I get a blink of 4x4 light after about 3-4 seconds af holding the 4x4 button and then nothing.
Still I think a service to the system will fix this. re grease of the hubs and full service of the bearings and seals. I like the vacuum system when it works and with my experience of frozen manual hubs they would not help me so i cling to my original ones still They worked down to minus 8.

Last year I thought I had a problem with the front hubs, my back wheels lost grip, so put it in 4WD and it didn’t seem much better. A few days after I jacked up the front and tested the vac hubs, both worked correctly.

All has been great until Saturday, it was cold and there was ice/snow, the back wheels spun when in reverse up a steep drive. I put it into 4WD and tried again, it was better, but I still felt the back wheels slip, I am pretty sure the front didn’t.

Both times the green light came on, but then it comes from pressure not hub position, I think?

Is it possible that that one or both hubs work sometimes and not others? If only one hub was engaging and not the other, would you still get good drive from that wheel or would it cause problems with the diff?

You need both hubs to engage to see useful drive otherwise you will just rotate the diff centre.

Thanks Lambert, that explains the Eddie's (original poster) experience, one drive shaft turned but with no power, the second not at all.

So if one hub vac line is blocked, you get a steady green light, but no 4WD. I suppose you could have one hub sticking in cold weather as well?

I might jack mine at the weekend and check operation.

I used the earth conductor from some twin and earth cable. If you have a compressor then the small air guns you get to use with them would do the job.

Mine had no light at all from pushing the 4x4 button. At first when it failed a blink after 3-4 sec, but later in the week nothing.
Now with only minus 2 it is working fine again.
I suspect the actuator was frozen. I had been driving in deep powder snow and minus 15 so most likely packed underneath with snow.

If the actuator engage but the hubs not, the light will flash?
Or could it be the vacuum sensor at the intake manifold?
Or does it still flash the light if that one is out?

Just jacked the front of my Jimny and neither vac hubs are locking.

I get a solid green light on the dash and the transfer box is working as it locks the front drive shaft. The solenoids are clicking so my guess is it is something common, perhaps aa blocked pipe where it is common?

Apart from taking the vac hoses off each hub is there an easy way to tell if the vacuum is working or not, or possibly blow out both lines from the solenoid?

Robin