Vacumm Hubs Just For a Change

Performed some more testing.

When engaging 4WD I hear the click of the transfer box and the lock solenoid, then very soon after I get a solid green light, almost no flashing.

If I disconnect the lock pipe at the solenoid, but leave the switch connected, I get a flashing light.

Also if I run the engine then switch it off the light will go green, but do it a couple of times and I get flashing green.

This all kind of indicates that the vacuum is working, but the fact that it quickly goes solid green suggest a blocked line?

I even pulled the hoses off one side and got a solid green, so you would think it was the lock line that is blocked. Does all that make sense?

I managed to get an airline at the solenoid and tried blowing the line through, but couldn’t get a good seal. I expected to see a bit of pressure on the line but there was very little and didn’t get chance to try the unlock line. Am I on the right track here to blow the lines through from the top?

Thanks

Robin

I have had a good go at trying to blow the vac lines through. The lock line has a small amount of pressure even when disconnected at the hubs, the unlock line has no or very little pressure. This still seems to point to a blocked line?

Can the lines freeze up inside if they get moist air in them?

Now when I engage 4WD, the green light goes to solid for about 2 seconds, then flashes a couples of times before going back to solid. The hubs don’t engage.

It’s too cold to start trying to pull the pipes off it, is manual hubs the way to go until I can replace the hose?

Robin

As a manual convert I would have had them changed at the moment of failure. Grovelling about in the cold under the car trying to fault find the vacuum lines is not on my list. And given that I have to get out of the car to open gates switching the hubs is really not an issue. Just like leaving the hubs locked all day to select 4x4 as needed if they forecast snow is similarly not an issue.

If it's too cold to fix the vacuum system it's too cold to fit manual hubs in my opinion. 
I quite like the vacuum system and my preference will be to try and keep it working if it goes wrong.
But I fully understand the lure of the manual route, a sure quick fix for a known price. It's down to what you desire 

Apart from the cold I am just not getting anywhere and really want to get this fixed before Xmas, plus been at work for the next few days won’t help.

I think what I will do is order a pair of manual hubs, see if I can get them this week and fit one day, they will be quick to do, I have had both hubs off before.

Then sometime next year when the weather is better I will tackle the vac hubs/pipes and see if it can be fixed, if worst came to the worst, just get some 4mm vac pipe and a couple of tees and run new lines.

I assume AVM are the hubs to get? At least one supplier is showing stock and offering DHL/DPD. Not sure if Martin sells them, I can’t find them in the store?

Robin

I now Think - 4 is ok on mine and below that the 4x4 is out. I though if your lights flash there is a vacuum fault. Then the manual hubs will help. Mine has no lights at all when it is - 8, and work perfectly around zero C.
So I suspect the actuator underneath is the problem on mine.

Or when i Think of it, if the hubs do not engage, the actuator can't engage the front axle can it?

Will check lines one day, should be "warmer" in a few days.

Hi, my Jimny has stopped engaging into 4x4 just now. The light has stopped coming on on the dash when I press the 4WD button I hear a click under the dash  make a noise then 3 secs later another click but nothing happens, if I press 4WD-L it beaps 3 times .I just changed the king pin bearings and checked the metal air intakes on hub and was able to blow air through them. If I pull the electrical plugs of the 4x4 near the actuator the green lights come on the dash.
I'm puzzled what this could be.

From what I understand when you press the 4x4 button, the transfer box moves first, then the solenoids initiate the vacuum to move the hubs.

This makes sense, it would be less likely to create a problem when moving if the transfer box had connected the front drive shaft first and certainly with mine, when in 4x4 the drive shaft is connected, it's the hubs that aren't moving.

It's much warmer here today, at one stage when trying the 4x4 the transfer box would engage and then the green light would flash. If I tried it again, I would get steady green, I am pretty sure the hubs didn't lock. I still think the vacuum is working on mine, it's just the lines are blocked/frozen or may be split and blocked.

I ordered AVM manual hubs this morning, we have a forecast for snow and I have a trip to make in a weeks time, so need to have 4WD working and this is going to be the fastest way.

I now you can leave the manual hubs engaged and switch between 2 or 4WD using the transfer box, but I guess it is best to stop first with manual hubs engaged, otherwise the front shaft and gears inside the transfer box will get a load shock?

Robin

For no 4WD light have a look here

www.bigjimny.com/mediawiki/index.php/4WD...ult_finding_overview

If there is no light or flashes once, the fault finding guide suggest a fault in the transfer box, transfer box switch or the fuse. If this happens, it returns the transfer box to 2WD and doesn't try the vacuum.

Finally my problem from the same guide, I might have faulty or sticking hubs, this would be great news if it is, but I really want to get 4WD working again and new manual hubs is still the answer even if I go back to vacuum hubs at a later date, or for the summer/normal driving and switch to manual hubs for the winter or when at an event.

Ok thanks for that Robin.I will go through what it says in problems 1 to 4 and see if it shows up anything similar to what it says. I've already checked the fuses and there all good.

Dr. Robin, it certainly sounds like you have a blocked hose. When you do come to replace the hoses I recommend routing them around the engine bay and down the brake hoses rather than the replicating the somewhat vulnerable standard route along the radius arm and then along the axle. To help keep track of which hose is which when doing this I cut the ends of the lock hoses at 90 degrees and the un-lock hoses at ~30 degree. It saves more problem solving when your hubs are clicking opposite ways, or when you have to pull the hub off at a later date.

Thanks for the advice, I will make sure I mark them up and route carefully.

Just out of interest how far do the hoses go back along the radius arms? I wonder if I might have trapped a hose when I fitted radius arm protectors?

If I replace the hoses, I assume it is best to put the T-piece joint at the top and run four hoses down, rather than putting a joint down below?

My AVM manual hubs are to be delivered today, but I have been going back through all of the tests I did and if it isn't the hose which is blocked I think both vac hubs might be stuck.

The problem is the existing hose is difficult to see and involves a lot of lying down under the car, whereas the hubs are relatively easy to change. I don't mind having a spare set of [manual] hubs, but need to get 4WD working for Xmas.

Robin