Hey guys,

I'm trying to help out my sister-in-law and diagnose why the 4x4 system on her 87 4runner has stopped working. She is pessimistic and seems to think that it will be the transfer case, but I am curious to know if it could be something as simple as the hubs or easier. I don’t much about the vehicle (I own an isuzu) so any help/advice would be great. Is this a common problem? The transfer case lever moves in and out of the gates but nothing seems to happen.

Cheers,

Neilson

Did you turn the hubs to "LOCK" ?

Does the 4WD indicator lightup ?

Does her truck have A.D.D.?
Automatic Disengaing Differential
This is vacuum operatedand in cold weather the things get a bit sluggish, new differential lube sometimes helps.
What are her symptoms?
You say "nothing happens" the truck wont move? or just the light doesn't lite?
Need a little more specifics.
Automatic or manual Tranny?

Thanks for the speedy replies guys.

As far as i know, its an 87, 22re, 5 speed and it has auto front hubs. We live in a ski town, and its been pretty cold of late, so checking for seized hubs will be a good place to start. I'm not sure if the dash 4x4 light comes on, but i do know that when you select either 4hi or 4lo, the front wheels just don't turn!

NEILSON

Try this test. Make sure you'e in 2WD and hubs are not locked. Park and turn engine off. You should be able to turn the front DS by hand. Now shift t-case to 4WD, you should not be able to turn the DS. If you can, the t-case sounds like the culprit. If you can't, t-case should be OK and hubs maybe the problem.

If it has the ADD then it will only engage when there is vacuun to the diaphram on the differential. The switch that energizes the indicator is also in the differential and only actuates when full travel of the ADD mechanism is reached. Pulled in by teh vacuum diaphram. With the engine of this will never happen.

I am almost sure that ADD is different than Automatic Locking Hubs. Automatic Locing Hubs work by utilizing clutches and springs and stuff. My '88 5-speed Automatic Locking Hubs worked fine for years. I was often told that I should take off the Automatics and install some Warn Manual Locking Hubs. I always thought, "Why?". As I learned later, they have a tendency to Not work when you need them the most. My Automatics were staring to pop and make noise in 2-wheel drive, almost like it wanted to engage itself into 4-wheel drive, typically in colder weather. I had my 4X4 mechanic install some nice Warn Manual Hubs, problem resolved.

I am almost sure that ADD is different than Automatic Locking Hubs.


Thanks, wasn't sure.

I had that problem and it turned out to be the Acuator in the front end, it pushes the lock in place so your 4 wheel drive locks in and works and also the 4wheel drive light did not come on. But sometimes it would and I knew I wasn't in 4wheel drive I do have auto locking hubs but it's worth a try to check before you get into digging in the transfer case. I know the Old Dodge's had this setup and I'm almost positive it was on there free wheeling hubs. You had to shift it into 4wheel drive just like our 4Runners and the Acuator would do the Actual Shift in the axle.
I hope this helps, Good Luck.
OzzyO