Transfer case, lock not disengaging

[twopointsevenone Lurker Find all posts View Profile Close twopointsevenone]

Hello

I have a 1997 manual transmission, diesel 125 hp series 90, 147000 km, mine has permanent 4wd and a center differential.

I almost got stuck in a rocky and muddy stream with ice cold water (4300 m altitude, Chilean Altiplano). To get out, I had to reverse in low gear and step on the gas more than I liked. When the rear wheels got solid traction again after spinning, there was a nasty mechanical bang but the car got out of the stream.

So now the transfer case lock won't disengage, which as you know is nasty on pavement. I'm still driving in search of a mechanic who is competent to fix it. Thing is, in Chile, the Prado 90 is very rare and no one can get parts for it.

I removed the connector of the actuator on the "extension housing" and there was mud in it so I cleaned it. No improvement.

I have all the official Toyota manuals, but there's not a word about the actuator.

I removed the actuator. It consist of a magnet that can brake a disk or not. The disk is connected to a plastic cog (gear) of about 25mm diamater.
When I turn on the ignition, the diff lock light does not come on. All other lights do.

I would expect that if the actuator was bad, that there is no lock engaged.

So I'm getting the impression that something inside other than the actuator is mechanically broken.

With all 4 wheels off the ground and in 1st gear, the rear propeller shaft could be turned by hand but the front one couldn't.
With all 4 wheels off the ground and in neutral, both propeller shafts could be turned by hand.
With all 4 wheels off the ground and the motor running in 1st gear, the front wheels turned but the rear wheels didn't.
With all 4 wheels off the ground and the motor running in low gear, all wheels turned.

The 20 Ampere DIFF fuse is OK.

Iīm reluctant to start getting the transfer case out and apart without access to spare parts. I think I will have to drive to Argentina like this, where the Prado 90 is common, as I am told.

A few months ago, I had a similar incidence when stuck in clay, and the transfer case failed to unlock for a while. But after a short time, the problem disappeared.

Questions:
- Should the diff lock light come on when the key is turned to on?
- When the actuator is inactive, is diff lock off or on?
- Any other ideas how I could get rid of the lock until I find a mechanic?

Sorry for the very long post. Greetings from sunny and windy Calama, Chile.

[lugueto Junior Member Find all posts View Profile Close lugueto]

Does the truck run fine after that? no recurrent noises? Just the diff light on??

How about banging when taking off under load or uphill? If so, try removing the front shaft and going for a calm test run without it. Try a few uphill starts and see if the banging is still there. If it is, its your transfer case's chain which is worn, and is perfectly normal.

To see if the banging is there instead of starting uphill on under load you can try taking off in LL. But don't overdo it.

[glen_ep Addicted PP Member Find all posts View Profile Close glen_ep]

Sorry I don't know enough about the transfer to offer mechanical advise. If you need some information about the transfer I posted a few links here recently: http://www.pradopoint.com/showthread...l=1#post430776

But.. I'm a confused about one thing. You said it's nasty driving on pavement whilst the centre is locked. Yes, normally you'll experience a drive-train/transmission windup and steering will become difficult - but normally both front/rear prop shafts are being driven. From what you've said, your rear prop shaft is not being driven by the transfer case at the moment (a failure). If that's the situation, and all drive is going to the front, then I wouldn't expect any windup to occur, presently. So that begs the question, what is presently occuring whilst driving on pavement?

Normally I'd suggest removing the front prop shaft to continue driving, but without rear drive you will go nowhere.

PS - I don't think the centre lock light illuminates during starting, but I'll try to check mine soon and advise.

[twopointsevenone Lurker Find all posts View Profile Close twopointsevenone]

Thanks m8s.

The differential was severely damaged (beyond repair) all along, but the broken metal pieces created a strange and counterintuitive situation so that most of the time it was front wheel drive but sometime what appeared to be a lock. The regular diff lock did not work at all, so the light did not come on. I made a major fool of myself by thinking, and posting, that the speed sensor was an electric diff lock actuator. It's not of course, and the lock is activated mechanically.

The front wheel drive made the steering unsteady, which reminded me of lesser cars earlier in my life. I also had frontal wheelspin on dirt but I figured it's because there is more load on the rear wheels. Never mind that I never had frontal wheelspin before.

I had the front propeller shaft removed and the car didn't move at all.

So I drove "happily" 520 km with a broken central diff, to Salta, Argentina via Paso de Sico, very cool route, about half unpaved.

The boss of Todo Toyota took the transfer case apart and revealed the destroyed diff. It's the larger of the two planetary gears, the one enclosed in a "bell". So the diagnostic is essentially completed.

Now I'm struggling to get a new diff. It's unavailable in Argentina (and perhaps in entire South America), they could import in from Japan in 30 days but they couldn't quote a price. Apparently, some D4D Hiluxes (SW4, not pickups, but station wagons) use the same transfer case but the differential is just as unavailable.

Let's see if I manage to post a photo of he broken diff.

[glen_ep Addicted PP Member Find all posts View Profile Close glen_ep]

Is importing a second hand unit from USA an option for you? If my prior research is correct and the model is VF4B / VF4BM, than 4Runners and FJ cruisers may be possible source vehicles for second hand units. Please don't order based on my information though, research and confirm first.

[lugueto Junior Member Find all posts View Profile Close lugueto]

Well, I dont think it is unavailable in all of South America. I bought a unit new from Toyota Venezuela a couple of years ago, and believe me it is tougher to find parts for vehicles here than anywhere else in the world. If I managed to find one rather quickly at that time, im sure you'll be up and running in no time.

Cant remember the part number though, Im guessing there's no difference between the gas and diesel models?

I wonder, how did you manage to break the center differential mechanism without binding or strechting the transfer case's chain before that??

How do you use your vehicle?? as a "serious" wheeling rig or an expedition style rig??

Cheers.

Luis

[glen_ep Addicted PP Member Find all posts View Profile Close glen_ep]

Is importing a second hand unit from USA an option for you? If my prior research is correct and the model is VF4B / VF4BM, than 4Runners and FJ cruisers may be possible source vehicles for second hand units. Please don't order based on my information though, research and confirm first.

I've been doing a little digging around... In USA, it seems the FJ's VF4B transfer is a wanted commodity amongst the 4runner crowd, so second hand units may be hard to get. However, the FJ owners are replacing their VF4B transfers with either the Atlas or the Inchworm Lefty. The Inchwom Lefty is a part-time case based on existing Toyota cases'. If the VF4B can be replaced with the Inchworm Lefty on FJ cruisers, then perhaps it's a suitable replacement part for our Prado's as well. Whilst not cheap, it would offer part time, lower low-range gears, gear driven (instead of chain driven), and the options of twin stick or even dual-transfer.

[twopointsevenone Lurker Find all posts View Profile Close twopointsevenone]

glen_ep:
- Importing into South America is for practical purposes impossible for me because of slow customs procedures, lack of a residence and bad Spanish. The mechanic is not set up to import stuff either.
- Atlas, Inchwworm: This seems like serious enthusiast parts, not something I was expecting to get into.

Iugueto:
- Why the chain did not let go first, I can not answer. In the first incident the wheels were one quarter to half in clay. To get out, I had to jack up one wheel at a time and put rocks below the sand plates (4, fiber glass). When I got out, there was alternating wheelspin and hard traction. This is where the initial damage occurred.
- I have somewhat oversize tires, 265/75R16. Next tires will be standard size 265/70R16 to give suspension and drivetrain a slight break.
- My usage of the Prado I would say is hard overlanding. There is no intention of wheeling as a sport but I drive any track or piste if I want to go somehere. I managed to bring down my (old) OME 881 springs (medium hard) in about 150 off pavement days. I'm a perpetual traveler since January and drive off pavement 2/3 of the days.
Total weight is 2800 - 3000 kg. I have 100 L water capacity, 220 L Diesel and about 30 kg of reserve canned food. This will help me to not panic and stay alive should a problem arise.

The local mechanic found a transfer case from an accident D4D Hilux as a donor. He is sure that it contains te same diff. It will cost me 7500 ARS = 1410 AUD. I might be on the road again tomorrow.

[glen_ep Addicted PP Member Find all posts View Profile Close glen_ep]

Wow that's a serious failure! Based on my interpretation of this document I'm guessing that's the Planetary Carrier which has self destructed.

Thanks for the photo.

[lugueto Junior Member Find all posts View Profile Close lugueto]

Serious failure indeed.

The tires aren't the cause of that damage.. I've seen prados using that tire size go through hell and back without such damage. Hell, I even owned an armored 95 that weighed maybe 3200 kilos unloaded, went overlanding regularly and ran 265/75 tires that never had damage nearly as catastrophic as that. Sold it when it had basically the same age as yours, around 155000km.

Did you buy the truck first hand? Im guessing strain of driving on the city on HH caused the center diff to systematically fail and when it was on front wheel drive only it was the drop that spilled the glass for the diff and ended up destroying it? This might be a scenario? water in the TC fluid??

[twopointsevenone Lurker Find all posts View Profile Close twopointsevenone]

Wait a second. VF4B? Pretty sure I have a VF3B, no torsen. Please stand by, should know more in a day or so.

[glen_ep Addicted PP Member Find all posts View Profile Close glen_ep]

Hmm I haven't checked mine for a code, perhaps it is the VF3B.
http://www.tlocuk.co.uk/forums/viewt...f82f19216fb18b

EDIT: Yep, checking the engine code (5VZ) in my original document (here) indicates that the transfer should be a VF3B. Sorry for any confusion - I only done a little research on this recently. Looks like the inchworm lefty is out

[twopointsevenone Lurker Find all posts View Profile Close twopointsevenone]

OK, the car is repaired and running.

The hoped for differential out of a donor transfer case of a Hilux didn't pan out, very different. The mechanic spent a total of about 3 hours getting parts, to no avail. So I ordered the parts in Switzerland, because that's where my girlfriend lives and she was supposed to join me on my trip in a few weeks. After she had the parts, she had a medical emergency and canīt travel for about a month. The six parts cost about 1000 USD. So I spent 4 days flying to Switzerland and back, getting the parts and also a quite a lot of foto and camping stuff that my girlfriend was supposed to bring. Mechanic installed parts and transfer case today, his bill amounted to about 500 USD including some minor oher work.

There was no water in the transfer case.

I thought about it some more and I do not think that I abused my drive train. During a recovery, you have to get out or rot there and it's not always possible to be particularly gentle to the drive train. So I think it shouldn't have broken. The six (stationary) shafts that hold the gears in needles in the planetary gear main carrier seem quite weak.

I've had the car for 80000 km, so pre-owner damage would likely have surfaced earlier.


Thanks again, you've been great.

[twopointsevenone Lurker Find all posts View Profile Close twopointsevenone]

Update: Junior mechanic installed my transfer case and he managed to wedge the spring that pushes the lever to the left between the transfer case and the lever plate. So transmission oil leaked, from the top. At first I thought it was just a bit of excess oil, but after a few days it ran on about 0.8 liter below normal. Other mechanic shaped me two new gaskets and I installed the spring correctlly. Hope it's all good now, fingers crossed. Greetings form Uyuni, Bolivia.