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My 4wd won't disengage on my 73 712M. The first lever is up and the light is lit. I tried to pull the lever down and it feels like it hits a mechanical block half way. When I open the bleeder I can get the lever to go al the way down when it goes back up it I get the same problem again. I have flushed the hydraulic line with over a qt of Dot 3 and it is pretty clean. I disconected the slave cylinder and went forward and back a few times still wouldn't disengage. The truck was like this when I bought it. I only drove it about 1/2 mile in 4wd.
Question #1 what can I do to get it out of 4WD.

Question #2 is will it harm anything to drive it on the road(blacktop) with 4wd engaged to try and get to disengage.(Thinking of changing the fluid in 4wd case with some new stalube GL4 and then driving with the slave out of the case to see if the 4wd will unlock)

#3 Can I disconnect the slave cylinder and the switch on the other side and unlock manually somehow or does the box need to come out and opened up.

I have searched and looked at at least 7 or 8 threada on thisthat is where I got the ideas for what I have done already but none of them really worked on my truck.

Any help or suggestions will be greatly apreciated.

Thanks from a new pinz owner

Lift one front wheel off the ground to release any stress on the splines. Jiggle the wheel till it will spin.
Most likely some rust on the internal slider.
That should get you started.

Jim is probably right but on my thread

4x4 won't disengage all the time when I flip the lever

I had to have a friend pump the lever adn I worked the bleeder and I got some nasty crap out of her.

It works perfect now.

Thanks MR DAVE DUNN btw on that one ...don't know if I thanked you ...sorry.

Jer Bear

Mopar,

FWIW, Dave's the guy. But I'll add a few thoughts.

First off, make sure you're dealing with the correct locker. There are 3. One is behind each differential, and one is just ahead of the transfer case. Since it's your leftmost locker lever which is troubling you, you are dealing with the locker at the transfer case. Flushing the other 2 won't effect this issue.

Q#1: When the lever is down, try loosening the bleeder and fluid should come out. If nothing comes out, remove the bleeder. Check the bleeder for being plugged - it's common if the bleeder isn't capped. While the bleeder is loose, try Dave's suggestion of lifting and turning a wheel. If it unlocks this way, your problem is likely in the lines and/or master cylinder.

If this still doesn't unlock it, unbolt the slave and remove it from the central tube. Again try to unlock it by turning the wheel. If it unlocks this way, I'd check the slave for gunk.

If, with the slave removed, it still won't unlock, I'd take it for a short drive off-road, trying to induce some back & forth movement into the drive train - accelerate and then decelerate, or go over some bumps - to hopefully get it to unlock. If it doesn't unlock then, it may be internal to the locking mech or maybe in the diff(?).

Q#2: I would not drive it "locked" on the highway. I would not guarantee that you'll damage anything, but the differentials are there to relieve stress on the drivetrain caused by the tires rotating at different speeds during cornering, etc. There is no differential between the front and back wheels, thus driving it "locked" will likely induce stresses. Whether is harms the truck, :?: :?:

Q#3: The slave cyl. comes out via 2 bolts. You'll also find a lose spring and a pin which engages the light switch. The switch has a cover which is bolted on, and then the switch screws out. If, after removing the slave and pin, and trying to get it to unlock, it still remains locked, I believe you're then looking at removing that assembly from the truck for internal work. (Dave, Jim, etc. please correct me if I'm wrong here.)

In case you don't yet have manuals, you will want to buy them.

Thanks for trying to search this out. It can be difficult to find what you need sometimes.

So far, in my experience, stuck lockers have all been hydraulic related. Hopefully this is what you find too.

Good luck, and I hope you're able to enjoy that truck soon.

Paul

Paul thanks for the suggestions I have done all that already and it doesn't seem to be in the hydraulics as nothing happens when the slave is disconnect(removed from the box).

Jim I'll try that trick with raising the front wheel off the ground and work it does it matter which one?
I attempted to do this by rocking the truck in forward and reverse but it makes sense taking off the binding pressure off by raising one wheel .

If I get it free and it was stuck from being rusty should I flush the box with anything to clean it up.
Thanks
Sean

:idea: Any chance the electric switch is stuck in the on position?

Ed

Ed,

I don't think it's possible that a stuck electric sw. would cause this. It's activated by a spring loaded pin. The sw. staying on would still allow the pin to move backward. (I think) Please correct me if I'm wrong here.

Mopar,

There is a front to back movement at the front end of the transfer case (a collar) which needs to happen, in order to lock the transfer case's forward output to the front drive shaft.

If the slave's removed, the locking collar should want to disengage. (IIRC, it's spring loaded) Other than removing any drivetrain stress, as Dave suggested, it may be within the locker mechanism. I believe this requires removal of the rear 2 axles and transfer case assembly. But then just a easy removal of the locker from that assy.

You want to lift only one front wheel. If you lift both, you will need the front diff engaged. Basically, you want to move the front driveshaft relative to the transfer case. (I hope this makes sense)

P

Shheezzz, now you're forcing my memory on the working of the old hydraulic lockers ... The lamps switch is a grounding circuit that when the locker pin engages, grounds the lamp circuit.... not common to fail, but knowing what some have done to their trucks, anything is possible. "Gunk " is known to have collected on the pins, and have enough pressure for it not to release. A repair manual has the teardown in it ( I only have 716, LR101 and Supacat manuals where I am presently ).

Another trick to get lockers to release is to drive slowly in reverse in a "S" pattern, this usually releases any pressure on the drivetrain and the pin releases.
But if your truck was driven on hardpacked or paved streets enough, it could be bound and require a teardown

undysworld wrote:Ed,

I don't think it's possible that a stuck electric sw. would cause this. It's activated by a spring loaded pin. The sw. staying on would still allow the pin to move backward. (I think) Please correct me if I'm wrong here.

My bad. Had brain fart, forgot the lever is jamming.

Ed

Well I got it out of 4wd

Tried all the above and no dice still locked. So I took out the slave and pin for about the 6th time. Took of the switch plate from the other side unscrewed the switch 22mm sock(very liitle clearance between muffler so I had to fit a regular socket on over terminals and get just enough bight on the ratchet to unscrew the switch)which has a long spring loaded pin on it. we tried to use a punch to push the pin nothing. So I went to the slave side and stuck a screw driver in the slit on the pin while my buddy pushed with the punch from the other side. I tapped the screwed driver with the baby sledge and the sleeve around the pin moved out (suprised me as I wasn't looking for a sleeve) the sleve came out put it back in and it was out of 4x4(really 6x6). rolled forward and back put it in 4wd and then released it and now it seems to work.
(not registered yet so I will have to wait till next week to give it a full on the go test.

The repair manual diagrams were very confusing and of little help just some plain old luck and trying.

All of the suggestions were helpful and very appreciated!!!!

Some where along the way I lost my turn signals and locker indicator lights. now to figure that out maybe a bad breaker!!

To better understand the locker, look at the parts breakdown.
The part that usually causes this is the spring guide that rides on the O.D. of the hollow guide pin as it is the release side of the fork.
The pin can get surface rust or varnish build up from heat and lack of use.
Pushing on it from the switch side got it unstuck and most likely cleared the debris from the pin.
To lube it all back up just find a dirt road and engage and disengage locker to verify repair.

There are images of locker box in several posts

hi i work on a modified landi 88 with volvo 303 portals having problem with front diff lock does not engage even manually buy hand
any one have ans tnx mand

Mand,

This portion of the forum is pretty Pinz-specific. Scroll down further for Volvo stuff, and post it there. Much better chance of an answer.

Regards.