front drive engaging?

Busta wrote: If you heard the hubs engage and the 4wd light was on but not flashing then it sounds like the vacuum system is working fine. If the vacuum system did have a leak, it would only start hissing when you selected 4x4 and would stop after 5-10 seconds. I very much doubt you would hear it from inside the car!

Just to make sure, you are aware that even when in 4x4, you may only have 1 wheel spinning on each axle? So if you looked at the drivers side wheel and it wasn't spinning, the drive would have all been going to the passenger side wheel.

I heard something engage, not sure if it was one or both of the hubs though. The vacuum system could give the impression it still works, even with a blockage in one, or both of the pipes from the valve controller.

I definitely heard a noise that sounded like a hissing, but it could have been anything when the engine was running. I was thinking if it was the vacuum system, it could be the tank which stores -ve pressure that has a leak, it's up in the wing not far from the driver position, so could possibly be something. Or it could be a red herring. I'll have to have a proper look at it when the weather is a bit fairer.

I'm well aware that 1 wheel on each axle should be spinning. :laugh: I had a good look around the time I was pushing the bonnet and slipping around in the mud.

Ok,

So I had a proper look yesterday. Jacked up each wheel on the front individually and tested out 2WD and 4WD. The hubs didn't lock on either side, although the green light flashed and then went solid after 3 seconds, so the pressure switch 'seemed' to be operational. Took the hubs of both sides, functioned them in my hands and found they were working fine. I then cleaned them out, re-oiled and lightly greased them. But before refitting them, I manually put them in the locked state and checked the 2WD and 4WD switching. I seen that the front prop shaft moved when in 4WD, this proved that the transfer box was engaging the front prop shaft and that there was no issue with the half shafts driving the hubs. So I took off the vacuum hoses behind the brake discs and confirmed that there was vacuum -ve pressure on both sides. When I left the hoses off both sides and then pressed the 4WD switch, the green light was left flashing and I couldn't operate the 2WD/4WD switches. I had to reconnect the hoses, then restart the engine to reset the light.

So, in the absence of a vacuum pressure gauge, it looks like there is probably a leak in the hose/piping. The next step for me will be to plug a hose and vacuum directly to the fitting behind the brake disk and test the hub under pressure to see if there is something obstructing it there and preventing it from moving. Anyone know how much a new hub seal kit might cost?

You got the flashing light as you had removed the flexi hoses from the hubs. The vacuum switch said no vacuum.

When you put the tubes back on the green light went off so you have vacuum. Therefore no leakage in the vacuum pipes.

There is only vacuum in the top engage flexy hose for 5 seconds. Then in the lower disconnect flexy hose for 10 seconds.

I aslo had a problem using a vacuuum pump trying to get the hubs to engage. I did not find the reason for them not engaging.

Must have another look at that.

auchenblae wrote: You got the flashing light as you had removed the hoses from the hub. The vacuum switch said no vacuum.

When you put them back on the green light went od=ff so you have vacuum. Therefore no leakage in the vacuum pipes.

Yep, there's definitely a vacuum there. But as I don't have a gauge, I can't measure how many mmHg's there are at the hubs. I'm thinking there could be a blockage further up the line which is constricting the flow somewhere and not allowing enough -ve pressure at the hub. I need to manually apply a vacuum at the hub fitting directly to see if there's some sort of failure with the seal or fitting.

I'll order some pipes and T-fittings to do a total bypass of the existing systems piping, and also look at replacing the rubber seals on the hubs.

I applied loads of vacuum more than the engine can manage ( was it 50 KPA will have a look tommorrow at the vacuum pump), to the hubs and no joy so I lost the will to live and just set the hubs to 4WD and put them back on and disconnected the vacuum at the engine side.

I have decided to get it running again so will maybe strip the hub to see if the internal tubes are damaged.

eddie

50KPa, that's over 7 times the required pressure. Did the pressure remain steady after you reached that value. Did they hub seals manage to hold that pressure without you pumping air out?

I would like to test my hub seals, but I'll need to buy a gauge for that.