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.