'87 GL10 center dif cel.. Broken tach

[jason2o]

Hey all I already had an '88 gl d/r 5mt sedan, now I lifted it and picked up an '87 gl10 5mt fulltime 4wd sedan for my DD..

 

The GL10 runs great but... the center diff is always locked and displays a fault on the dash, leaks oil, tach no workie, and most of the switches around the gauge cluster are gone or defunct..

 

Anybody have any ideas about the Diff.. I dislike barking tires in parking lots.. valve covers are leaking like a ***************...

 

I did some research theres not much on the fulltime 4wd diff lock up..

Edited October 16, 2010 by jason2o

[Gloyale]

Check the operation of the Vacuum solenoids that activate the Diff lock.

 

They are on the upper portion of the engine bay, drivers side right by the Wiper motor.

 

They are identical to the 4wd solenoid/actuator set-up as the single range 5spd 4wd (pushbutton on shifter)

 

So you can troubleshoot the problem in the FSM as if it was a S/R 4wd that was stuck in 4wd.

 

Basically the idea is that there are 2 solenoids. Each one activates an opposing side of a vacuum activate cable/diaphram. The switch inside is a double throw/ 2 position switch.

 

For Diff lock (or 4wd) one solenoid is electrically activated by the switch, that one opens and supplys vacuum to the side of the actuator that pulls the cable to 4WD position.

 

For Diff unlock (or 2wd) the other solenoid gets power, vacuum to the other side of cable, disengages the the 4wd.

 

So first check vacuum supply to the solenoids (pull the lead hose with engine running, listen for hissing)

 

If that is present then check that the hoses running out of the solenoids to the actuator are intact and connected.

 

If that all checks out, test for 12v on at the solenoids, with the switch in each position, 1 solenoid should have power, then the other when switched.

 

If that all works, then test that the vacuum is being passed through each solenoid again in one switch position then the other.

 

If then it still doesn't work it's time to get under the car and physically try to operate the lever on the rear extension(RH)

 

Stuck= problem in the diff

 

Not stuck, shifts out of locked= vacuum diaphram in the actuator busted, replace.

[jason2o]

Thanks! Thats great info..

[jason2o]

Is the engagement lever/solenoid on the center diff in the same position as the one on a d/r trans..? The air solenoids on the firewall check out ok..

 

Thanks!

[WoodsWagon]

There's a big vacuum can bolted to the side/top of the transmission by the bellhousing that has a cable coming out of it that goes to the back of the transmission. Make sure the vaccum lines (there should be 2) are connected to the diaphram can. You can also connect each line one at a time to a vacuum source to see if it shifts in and out. Trying to work the cable back and forth at the lever end with a prybar is kind of the last resort.

 

You can feel the vacuum output from the 2 solenoids switch when you switch the diff lock on the center console?

[jason2o]

Well the can doesnt do anything, kinda frozen. Is there a source ( to purchase) for these things? Going to try and mess withthe lever manually..

[WoodsWagon]

The cable is probably seized. Take it and the can off of the tranny, shift the diff lock manually and use some baling wire to keep it held in the unlocked postition. Then get to soaking the cable in penetrating oil until you can get it to move again.

 

You may be able to get one from a pushbutton 4wd car to work with a bit of modification, if not I'm sure somone here has one you could buy.

 

Does it have a digital dash? If the tach isn't displaying but the alarm still goes off when you exceed redline it's just the display going south. The tach is kindof worthless anyway. I've had EA82's up to 8200 rpm's and then the valves start to float, just wind it out until it stops pulling as hard, then pound the next gear and keep it pinned. As long as you keep the oil filled and fresh you're not going to kill one by overrevving.