Prop shaft Universal Joints on LN130

[ro80rob]

Investigation Update

OK
So, following info from the links, I took a look under the bonnet. Yup, there were the two vacuum relays, their outlets disappearing front diffward.
Anyway, with the engine running, I disconnected the vacuum feed line to make sure that there was vacuum supply (if you know what I mean) at the relays. All OK.
I then checked if either relay had connected through the vacuum to its outlet (since the article states that the vacuum is used to push the sleeve on the axle in and out). No vacuum found.
I then pressed my 4WD switch and noted that the blue relay switched vacuum through to its outlet. On switching out of 4WD, I found that this vacuum switched off, but the brown relay definitely did not switch on. A quick check with a meter across the brown plug showed 13V across it. The coil of the relay measures 39 Ohms, so there is a circuit, but the relay definitely does not switch the vacuum. This relay of course is the one that should disconnect the ADD sleeve.
This means (if my interprettation is correct) that..
The ADD is not disconnecting, and remains in the 4WD mode (front prop spins but not driven)!
So
What have I done to the front prop/diff/ADD sleeve system. I have driven this vehicle at 70mph plus (max 80) with the front prop spinning being driven through the diff?
Also, how much do these vacuum relays cost. They appear to be fitted in a pair so I have to get the both. They don't appear to dismantle.
Any suggestions?

Cheers... Rob.

[nero279]

the front diff is an open diff, so should be ok, assuming fluid and breather's are ok i would think. Might be worth changing the diff oil as it probably would've got hotter than it was designed to and for longer periods of time.

Assuming the other end of the 4wd system is working ok and the transfer case was properly disconnecting the prop i think that should also be ok, again may be worth changing the fluid. But i'm no expert and someone more knowledgable may offer different advice.

I noticed on the EPC the other day that there are balance weights available for the front prop. so it could be that the extra use of the front prop has maybe thrown it out of balance. I would replace the duff solenoids and change diff and t/case fluids and see what happens. Sledge or Monsterer may be able to help with replacements solenoids from their breakers.

I'll reiterate again that i'm not a mechanic and someone else may well be able to offer sounder advice than I.

[ro80rob]

Fixed it

Well
After I'd come round after the man from Toyota told me the price of the vacuum relay set (£234 +VAT), I decided that I'd take a better look at my 'faulty' one. Turns out if you pull off the filter on the bottom and straighten the tweaked over wings of metal that hold the steel frame of the thing together, the bottom pulls out along with the spring and sliding valve seal.

Guess what, it was all perfect and should work no probs. I cleaned it up for good measure, and rubbed a drop of WD40 on the sliding valve and put it back together.

I then re-examined the paperwork on the links listed previously and noted how simple the circuit was. I reinstalled the valves and connected up the power connectors. I then used the pointy ends of my meter probes to push into the wire insulation. I noted now that the 12V of previously was now 10mV. When I pulled the plug, it was 12V again. A weak supply from the ADD relay!.

So, With the sub dash panel off I found the ADD relay (by feeling which one switched when the 4WD switch was operated) and removed it (hey it came off its metal tang nice and easy!). Mine has 'Fuel pump relay' written on the side of it, just to add to any confusion.

On checking the various spade pins, I found the relay coil quite straight forwardly (remembering the diode in series with it!), but also a connection of 1M Ohm. I decided to prize the relay open (easy enough) and found that the switching contacts were high resistance in the normally closed setting, and were not completely reliable on the normally open setting (i.e. closed when the relay operates). A couple of minutes with some wet and dry on the contacts and all worked great. Got to say I'v almost never come across a relay failing like this. Is this a known issue?

I re-installed the relay and hey presto, both vac valves now switch. I now find the switching to 4WD takes a couple of seconds for the light to come on, and likewise go off. I now have no vibration at speed (tho I'm convinced I'v put quite a bit of wear into the fron prop double joint), and my front prop is now free to turn by hand with 2WD selected.

Great!

Thanks again for all the help.

[nero279]

if you're worried about wear on the prop is it worth getting one off a breaker? Only one of the ones on here still got one left, i see the post earlier

[Maverick]

Glad you got to the bottom of it in the end. After changing the UJs I'd have been dialing Tony.

[PDR]

After reading this I checked my front prop… and found that it does not turn by hand.

I checked for vacuum with the engine running and the auto gearbox in Park. I found I had vacuum on the blue switch with 4WD selected, but no vacuum in either 2WD or 4WD on the brown switch…

Anyhow, there is no vibration or clonks from the front prop at any speed.

PS. Had another look this morning and found that a 50ml syringe connected up to the brown valve’s vacuum pipe will provide enough suction to disengage the AAD collar (and connecting it to the blue pipe will engage the collar). This was without the engine running. prop now turns freely.

I just need to find where the AAD relay is situated?

At least I now know I can engage 4WD when needed and I do have a way of disengaging the collar once back in 2WD.

So now I suspect it is the relay that is acting up or the brown valve.