Getting Diff-locks working. Checking process.

[KarlT]

Okay.
After years of non-working diff-locks have decided to do some poking around to find out why.

Current situation........
Front lock.......New actuator. Doesn't work, never worked, stuck shaft on front diff, dis-engaged, but bulb is always on.
De-coupler.......New actuator. Worked well on previous van, but is not working on this one. bulb doesn't light or flash.
Rear lock........New actuator. Doesn't work, Dis-engaged, shaft free. Bulb doesn't flash or light.

One way valve........ looked at at, tried blowing (mouth) through it, no luck (does it need more pressure?) either way. Which way should it sit in system.

What is the order of going through the system? What should I be looking for as I go?

[lloydy]

I found this
http://www.syncronauts.org.uk/?page_id=999
I have to free mine off too

[axeman]

if the front diff lock bulb is lit but it is not engaged then i think that the wiring at the switch is the wrong way round, also i dont think the a decupler bulb flashes pre engagement, may be wrong but mine dose not.

neil

[v-lux]

wiring at the switch is the wrong way round

More likely that the vacuum tubes are on back to front.

[KarlT]

Great link, cheers lloydy. Had alook on wiki, but was more confused than when I started!!

Yeah, I thought that was probably the case with the front bulb too Neil, cheers.

What way should 'one-way-valve' go?

[Aidan]

open end toward the source of vacuum

[KarlT]

wiring at the switch is the wrong way round

More likely that the vacuum tubes are on back to front.

Don't think so Al, as the shaft is stuck, out. But i'll switch it all round & see what happens......(& then forget how it should originally of been, as usual!! )

[KarlT]

open end toward the source of vacuum

Ahhhh, so the pipe that goes to manifold, can draw air out of the system?

[Mudlark]

The valve maintains the vacuum in the three ball reservoir after you turn your engine off; so while the engine is running its sucking the air out of the reservoir; when you turn the engine off the valve closes up as the air tries to rush back into the reservoir and maintains the vacuum on the business end of the circuit.

Sometimes the non-return valve sticks stuck and will not open or close; sometimes it sticks partly open and you might get a noise coming from beneath the van like a ballon being deflated by an 8 year old, after you have turned your engine off.

I have got to the point with mine where its either stuck locks or poor vacuum.

I used a spare actuator on both the front and rear (pull off the air lines and press them on to the spare actuator hanging free; pull your knobs and see if your actuator moves in and out. If you get actuator action then the 'circuit' is complete; then its a case of stuck locks or weak vacuum pressure as far as I can understand it.

If you get no actuator action you have no vacuum at the business end and you need to trace the line through chunk by chunk to see where its lost.

Weak pressure could mean you have leaks in the airlines somewhere in the circuit.

There are a fair few joints along the way and any split in the plastic pieces or splits,tears or holes in the rubber pipe are going to be suspect.

Anyone know how many lbs of pressure is actually optimum at the actuator?

[jebiga41]

also check your vacumn pipe from engine might have no vacumn (generally you would notice that your brakes don't work as well as they should, and no lights will come on the diff locks )

[silverbullet]

The most lbs available at the actuator will be at sea level on a clear day...(think about it)
Theoretically as good as -14 psig but probably nearer to -12 with a healthy engine and good valves etc.
Call it -0.9 bar (gauge)

[Mudlark]

The most lbs available at the actuator will be at sea level on a clear day...(think about it)
Theoretically as good as -14 psig but probably nearer to -12 with a healthy engine and good valves etc.
Call it -0.9 bar (gauge)

Clive has a wacking great vacuum guage he has used now and then; but i dont remember what it measured or how much he has typically seen on it. Anyone able to convert the nominal -12psig to how much dead weight (probably in 100's grams) the actuator should be capable of lifting off the deck if a sling was attached.

Just thinking that in the absense of a guage if you could say the actuator should be able to lift say 250 grams of dead weight off the floor with abit of blue petering with kitchen scales and a wire you could knock up a simple test for vacuum efficiency at the actuator.

Or is the process flawed?

[silverbullet]

It should be easy to use a fisherman's spring balance connected to the actuator (unbolted but plumbed in) Read off the lb force in incremements until the actuator won't pull?
Or look up the manufacturer's specs if an OEM supplier part number is available?