Following on from my other post, got the truck back with the 4WD light flashing. Now, i did ask him to double check if the 4WD was working, and he said it was, and was changing back into 2WD fine, so I'm not worried that its stuck in 4WD (I drove 4 miles home from the garage and nothing broke)

Bit of backstory, Had the ticking noise, took it in to get a service and for him to find out what the noise was, so engine has had a full service, filters and fluids, he has had the top cover off and the rocker off to check timing and do tappets, buts that's pretty much all he has had apart in the engine, so do you think, from being in those areas, he could have moved/touched, left off something that would throw the 4WD light flashing?

I have had a cursory glance and cannot see any vacuum hoses off.
The 4WD actuator rod is freely moving by hand
The 4WD lights stays solid when in 4H and 4L
The vacuum tank is solid, not rusted through and fittings are good
Most of the vacuum hoses i can reach quickly seem good, not blocked.

I have read most of the posts that state blocked metal vac pipes etc, but i was just thinking, because this has only happened after he has been in the engine, that maybe its something simple, but I just don't know where to start.
When i first got the truck, the 4WD light used to flash when i turned the ignition on (periodically, sometimes it wouldn't flash for days, then maybe once in a week) but only with the ignition on, and once started, the 4WD light would go out. So i know there may be a small vac leak somewhere, but once started, the engine seemed to hold decent vac, as there was no other issues.
Would there be anything else not working properly if a vac pipe was off or split or on the wrong way? is the 4WD vac system a closed loop? or tapped off the engine vac system?
EDIT: I have ordered some vac hose to replace everything i can get too, and will order some solenoids from Milners if i cant rectify this with new hoses, just wanted some advice on where to start in the bay as ill get a bit of time tomorrow to have a good look

when checking/changing vac pipes make sure you do them one at a time as it's very easy to get them the wrong way round (which may have already happened with yours)

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Thanks Krutly, Not sure ill have much luck going from a diagram to the actual engine bay, but ill certainly give it my best shot! I'm easily confused!

@4life-extreme has some photos in his gallery here -------> g614-New-engine-fitting.html

Hey Gibb - you won't be stuck in 4WD because when you go to 2H the front prop shaft is mechanically disconnected inside the transfer box. Additional to this, the actuator on the front diff allows the front offside axle to free-wheel. This stops the front wheels driving the crown-wheel in the diff, so the wheels don't turn the front prop shaft (similar system to free wheeling hubs). So basically, when you shift from 4H to 2H, the front drive mechanism is disconnected at 2 places, mechanically in the transfer box, and the electronic/vacuum system on the front diff. The flashing light indicates problems only with the electronic/vacuum system. Test it by idling the truck in 2H (handbrake on) and see if you can turn the front propshaft by hand - if you can't, then you know for sure the mechanism is not working (front wheels are still engaged with diff/prop shaft) - probably a blocked pipe, vacuum leak or bad solenoid (as your actuator moves freely). If you can turn the prop, the mechanism is working ok, but there is a fault with the detection switch or wiring - this tells the 4WD ECU whether the freewheel mechanism is engaged or not. The flashing light occurs when there is a mismatch between the transfer gear lever position and the output from this

Also, the system is driven by the vacuum pump on the back of the alternator that also powers the rest of the engine vacuum system. There is a small one way valve near the 4wd solenoids on the driver's wing, that should stop vacuum 'leaking out' to the rest of the system when the pump is not running (i.e, when the engine is off). If the system is working right, you should be able to switch from 4H to 2H even if the engine not running (when the ignition is on) though this will only work a few times till the vacuum in the tank is exhausted, as a little vacuum is lost each time you shift.

Hope this helps.

Top man Heathen, thanks for that, and thanks everyone for the info, bit wet up here this morning so not sure ill get a look at it, just really annoys me as it hasnt ever been flashing since i bought the truck and now, its going to be something small and silly, but that will take forever to find!

If it wasn't flashing before it went in, I would be thinking that something had been disturbed, as krutly suggests, more than likely one of the vacuum pipes. It could also be a very small split that you can't see

Just as a side note, What am i better buying? a simple vac testing gauge, or one of these vac pumps/brake bleeders with a gauge?
And the vac pipe is 3mm ID?

Quote: Heathen wrote in post #5

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Hey Gibb - you won't be stuck in 4WD because when you go to 2H the front prop shaft is mechanically disconnected inside the transfer box. Additional to this, the actuator on the front diff allows the front offside axle to free-wheel. This stops the front wheels driving the crown-wheel in the diff, so the wheels don't turn the front prop shaft (similar system to free wheeling hubs). So basically, when you shift from 4H to 2H, the front drive mechanism is disconnected at 2 places, mechanically in the transfer box, and the electronic/vacuum system on the front diff. The flashing light indicates problems only with the electronic/vacuum system. Test it by idling the truck in 2H (handbrake on) and see if you can turn the front propshaft by hand - if you can't, then you know for sure the mechanism is not working (front wheels are still engaged with diff/prop shaft) - probably a blocked pipe, vacuum leak or bad solenoid (as your actuator moves freely). If you can turn the prop, the mechanism is working ok, but there is a fault with the detection switch or wiring - this tells the 4WD ECU whether the freewheel mechanism is engaged or not. The flashing light occurs when there is a mismatch between the transfer gear lever position and the output from this

Also, the system is driven by the vacuum pump on the back of the alternator that also powers the rest of the engine vacuum system. There is a small one way valve near the 4wd solenoids on the driver's wing, that should stop vacuum 'leaking out' to the rest of the system when the pump is not running (i.e, when the engine is off). If the system is working right, you should be able to switch from 4H to 2H even if the engine not running (when the ignition is on) though this will only work a few times till the vacuum in the tank is exhausted, as a little vacuum is lost each time you shift.

Hope this helps.

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right to left that is...

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That's the one! and yes the vacuum source is on the left hand side in your photos.