4 wheel drive... working but not?

fallvitals · Post by **fallvitals** » Sun Aug 15, 2010 12:52 pm

So a little later we went through an area that was recenly clear for whatever reason, it rained last night and the dirt was loose. My buddy turned around, I waited for him to turn and back up this little hill to park. I decided to would do it better, (lol), well I was on a flat dirt area, loose and wet turning left on a incline. Well as soon as I got turned 90o I sunk up in the mud and got stuck. tried the gas and rocking the wheel no go. threw some rocks under the tire, no go. Buddy came down and we decided I should back up some (theres a drop off a few feet behind me) and hit it. Then he informed me neither of my front tires are spinning again. Nothing up front is grabbing at all. I was in 4 hi at the moment. So before back I switched to 4 lo, felt it kick in while backing up. Hit that hill again and started straight up. wheels turned left but went straight, lol. I backed up again back onto the flat area off the incline and got out of there, no problem.

Neither of us can figure out why 4wd is obviously working as it pulled me up that atv trail, but the front tire(s) didnt spin, grab, any thing while in that SOFT wet mud? I was pretty much a 2wd truck stuck. Which goes back to the first incident where I had to be pulled out. Any ideas?

Post by **HenryJ** » Sun Aug 15, 2010 1:01 pm

Lube the front actuator cable?

fallvitals · Post by **fallvitals** » Sun Aug 15, 2010 2:49 pm

Have I? No. I know little of that system, how do oh lube the cable just smear it on, what benefit will it provide to possibly correct this problem?

Post by **HenryJ** » Sun Aug 15, 2010 3:05 pm

You will have to take it loose at the actuator and front axle I suspect. Several have found them corroded and sticking.
Checking vacuum lines to make sure they are not leaking and the actuator to make sure it is functioning properly might be other things to check too.
Just shooting ideas "in the dark."

fallvitals · Post by **fallvitals** » Sun Aug 15, 2010 5:10 pm

Hmm... I'll have to check into it. Do some reading. It's just odd it works except for when I need it, lol. If I'm not mistaken the front pass tire should have atleast been turning, right?

What kinda front diff do we have?

Post by **HenryJ** » Sun Aug 15, 2010 5:15 pm

7.25" GM

fallvitals · Post by **fallvitals** » Sun Aug 15, 2010 6:21 pm

I googled and couldn't find a difenative answer. Is it an open, limited, or whatever diff?

I'll check the actuator. Looks like the problems are the vacuum switch or actuator... And I replaced the switch. I found a how to do a diy posi lock cable for $25 tutorial. If that turns out to be my problem that's a possible permanent fix....

It just seems like if it was the vacuum/actuator it wouldn't work at all? but it climbed that atv trail without a problem.

Post by **HenryJ** » Sun Aug 15, 2010 6:39 pm

open diff

fallvitals · Post by **fallvitals** » Sun Aug 15, 2010 7:06 pm

While I'm thinking of it, the turning hard in a parking lot in 4wd to listen for popping to confirm 4wd is working trick... Will that still work with our built up steering stops? I only turn my wheel 1 turn now vs 1 1/2 before building up the stops.

Edit, this sounds like me.
http://forums.s-10crewcab.net/viewtopic ... hilit=Posi

Im wondering if my front wasn't locking but when in 4 hi or lo it geared the back lower to help me climb that atv trail? I don't see that as possible... The front had to be pulling, but it obviously isn't spinning as my stuck in the mud incident today showed... I'll check on the actuator and cable. If it's bad I'm wondering if I should replace that faulty part or do the $25 posi set up...

Post by **HenryJ** » Sun Aug 15, 2010 8:19 pm

I would not do that with our weak front diff. You might end up 2wd for sure.

fallvitals · Post by **fallvitals** » Mon Aug 16, 2010 6:07 pm

Well i decided to do the parking lot thing any ways today in 4 hi. No differance in it and 2hi.

Why my truck climbed that trail,,, im not sure... maybe it did engage THAT TIME. Maybe the lower gearing helped me? But I dont think in 4hi the gearing changes for the rear just 4 lo? Either way, its obvious the push button is working, the transfer case is doing its thing, so has to be a vacuum issue some where...

Anyways, im rambeling like I always do. I figure ill put it on jacks have someone try 2hi then 4 hi see what happens. Then minipulate the cable or actuator to make sure it is fully engaged and see what happens.

If that is infact my issue... would the posi lock ($25 DIY http://diamond.site90.com/html/actuator.html ) be the best answer, or just repair the vacuum system?

I just wonder if I could run that wire to the current location of the actuator, mod it like he did, I dont think the bend it in the cable would cause a big problem in that location....

Post by **HenryJ** » Mon Aug 16, 2010 6:46 pm

If your cable is stuck, rusted, dry, corroded you need to fix it first.

Check to see if your front driveshaft is engaged when you select 4x4. If it is not locked in then you have transfercase / encoder issues. You might try a battery disconnect to reset it.

fallvitals · Post by **fallvitals** » Mon Aug 16, 2010 7:03 pm

Alrighty, inspect the cable as well. gotcha.

Front driveshaft does engage. I went out put a piece of tape on the front drive shaft. 2hi it didnt move. in 4 hi and 4 lo the tape changed locations after driving it a few feet. Back to 2 hi, and no more movement.

But off hand, if that is my problem would the better fix be a posi mod, or just replace stock parts? seems like the DIY posi would be a far more reliable and cheaper method. But not as clean...

Post by **HenryJ** » Mon Aug 16, 2010 7:25 pm

I have a posi-loc sitting on the shelf waiting for the time to come where I have to make that decision. I like the ease of operation that the stock system provides. I am not sure which way I will go when the time comes.

fallvitals · Post by **fallvitals** » Mon Aug 16, 2010 7:33 pm

I understand what your saying. I'm betting I'll have to make the same decision this weekend... I like the push button but I definantly don't want to do it again in a few years, lol, or track down a vacuum leak from a line, lol.

fallvitals · Post by **fallvitals** » Tue Aug 17, 2010 4:46 am

What is the best way to check vacuum hoses for leaks? I can't think of a good way with it still routed through the engine compartment?

Post by **HenryJ** » Tue Aug 17, 2010 4:53 am

Start it up and spray cleaner on them. Listen for changes in the engine speed resulting from ingesting the spray.
A visual inspection is a good indicator too. If they look bad, they are.

dozer1530 · Post by **dozer1530** » Tue Aug 17, 2010 5:05 am

i agree with that im replacing the ones on by the driver side fender this friday mine were dry rotted and cracked

fallvitals · Post by **fallvitals** » Fri Aug 20, 2010 4:29 pm

Front diff definantly is not engaging. in 2hi, front on a jack, one tire would spin.

Put it in 4 hi, to make sure it was locked in i drove about 50 feet, then backed up the same distance, kept it running so the cable wouldnt disengage, and only one tire would spin.

The actuator is moving, but im betting it is damaged and not moving enough. Tommarow im gonna remove the battery, to get a better view of whats going on, disconnect the cable and see what happens there/its shape.

I dont see how I can do the DIY posi and have a suitable mounting spot that isnt gonna put a bad bend in the cable, so im thinking im gonna bite the bullet and order the $200 posi lok kit. I definantly don't wanna have the vacuum system fail me again. I wonder how long its been like this? I bet since I had the truck...

though im still confused why it climbed that steep hill in 4hi but not 2hi?

Post by **HenryJ** » Fri Aug 20, 2010 4:50 pm

You do know that only one wheel will drive on the front right? It is an open differential.
All the actuator does is slide a collar over the right axle shaft to engage that wheel. That is what makes one drive wheel up front engage. Without it engaged the differential just spins and no wheel drives.

fallvitals · Post by **fallvitals** » Fri Aug 20, 2010 7:14 pm

Ya, as lame as that is.

But if it was engaged wouldn't atleast one (the right) be locked up the way I tested it today? I spun both, both spun freely. I was expecting one or both to be locked up if it was engaged?

Off topic, if it's only one wheel drive up front, then why have a cv drive one the left side if it's doing nothing?

Post by **HenryJ** » Fri Aug 20, 2010 7:29 pm

It is a differential. The spider gears spin. Each wheel will spin freely with or without the driveshaft fixed.

How a differential works - Youtube

Watch the video closely and I think you will understand why each wheel can turn freely.

To test yours you must have the driveshaft secured and one wheel stopped. Then the "free" wheel would be stopped as well. This will have to be repeated for each side to check things out. With both wheels in the air rotating one would cause the other to spin in the opposite direction. To know if it is indeed engaged by the shift collar you would have to give it some resistance. Hence the reason to have one stopped.

fallvitals · Post by **fallvitals** » Fri Aug 20, 2010 8:08 pm

That was an amazingly simple and very informative video. Felt like I was back in school but I actually learned something!

I understand the resistance part in testing it. I was expecting one of two things with both tires in the air, if the diff was engaged:

1) both locked up

Or

2) both tires spin but the opposite spins in the opposite direction, just like the rear drive shaft in the same situation.

I'll test again tomorrow, or Sunday, but I'm sure it isn't engaging...

Post by **HenryJ** » Fri Aug 20, 2010 8:16 pm

fallvitals wrote:2) both tires spin but the opposite spins in the opposite direction, just like the rear drive shaft in the same situation.

#2 would be correct. Wheel chocks and the parking brake set for safety. Be sure that the transfercase is engaged by checking to make sure the front driveshaft will not turn and the engine is running to eliminate the possibility of a low vacuum condition. Then use a floor jack to raise one tire at a time. Rotate the right front tire first to feel for the slide collar and to let it engage if the cable is indeed sliding it properly.
Really that should be all you need to do. If it is locked , then the other side is working as it should.

fallvitals · Post by **fallvitals** » Fri Aug 20, 2010 8:27 pm

Gotcha. I woulda took out the battery but my garage here is lacking tools, they are all sti at my parents house. I really need to fix up the work shop in there... But in my defense it has just very recently been cleared out of other folks junk so that it is useable.

I'll try all that out, check the cables, actuator, etc.

But, if it disconnect the cable from the diff, removing those 3 screws andhousing for the cable, will it drain the fluid?

fallvitals · Post by **fallvitals** » Sat Aug 21, 2010 9:03 am

The actuator is functioning flawlesly. Except...

Post by **HenryJ** » Sat Aug 21, 2010 11:08 am

Isn't it supposed to be attached to something?

blaz · Post by **blaz** » Sat Aug 21, 2010 11:31 am

Good find for an easy fix!

fallvitals · Post by **fallvitals** » Sat Aug 21, 2010 11:41 am

Yup yup yup. All three screws pulled out... I did find one below it with the threads from the hole still on it. Ever heard of this kind of failure?

I ran to lowes and got some larger short screws, all I had on hand was too small. But now I'm worried the larger screw might crack the housing and cause the same failure, or even the very same thing happening again... I think I'm gonna do the posi lock kit soon. There's just too much that can apperantly go bad in this system..

Still at a lose why it climbed that hill in 4hi with no front drive but spun in 2hi? lol

Post by **HenryJ** » Sat Aug 21, 2010 11:44 am

Does the cable move smoothly? Could it be seizing and the reason that the screws pulled out?

blaz · Post by **blaz** » Sat Aug 21, 2010 12:45 pm

Could have been yanked during the body lift too. Put in the larger screws, just make sure the pilot hole is larger than the root diameter of your screw.

roadrunner · Post by **roadrunner** » Sat Aug 21, 2010 1:08 pm

fallvitals wrote:Yup yup yup. All three screws pulled out... I did find one below it with the threads from the hole still on it. Ever heard of this kind of failure?

YES! I had the same failure. While my screws did not fall clear out they did get loose enough to prevent proper engagement of the front diff. This was discussed in another thread some time ago. This is why I usually ask when someone has a problem like this if the cable is sticking and whether or not the actuator vacuum pod is working correctly.

fallvitals · Post by **fallvitals** » Sat Aug 21, 2010 1:44 pm

Any thing is possible it could happened during the body lift, but I don't recall there being any tension on that cable.

The cable was as smooth as could be hoped for.

I think I read that in another thread, but for some reason I thought you ment the bolts in the fender well.

I didn't drill out the holes, but a #8 screw slide nicely in, and the #10 threaded nicely. It might last l
Without cracking.... But I'm very very tempted to get the posi kit so I never have to worry about this again. A new actuator will be $50 if this doesn't hold... So I would be part way towards the kit.

roadrunner · Post by **roadrunner** » Sun Aug 22, 2010 2:09 pm

fallvitals wrote:I think I read that in another thread, but for some reason I thought you ment the bolts in the fender well.

I recall a thread where another member was asking the location of the bolts holding the bracket to the fender well but I believe the issue of the loose screws was covered in another post/thread. I have had almost every conceivable problem with the 4x4 electric shift system there is to be had with our trucks since I've owned mine.

fallvitals · Post by **fallvitals** » Sun Aug 22, 2010 4:26 pm

Wow, if you've had THAT much trouble, why haven't you gone posi lok? I really wish I could think of a way to mount the diy posi. But I'm sure since iv had my 4wd it's only been 2wd. I put it in 4 hi in a sharp turn and I felt it, never recalled the feeling before.

roadrunner · Post by **roadrunner** » Sun Aug 22, 2010 4:44 pm

fallvitals wrote:Wow, if you've had THAT much trouble, why haven't you gone posi lok?

I gave it serious consideration along with the manual transfer case conversion. In the end I resisted because it all seemed like a "cobble-up job" to me. JMO Too much mechanic still in me I guess. Causes me to resist some of the more red-neck conversions. They may work okay but just not for me.

fallvitals · Post by **fallvitals** » Sun Aug 22, 2010 6:22 pm

Ah, I don't see the posi like that... I'd rather keep it stock but it's definantly a K.I.S.S. mod from the way I see. I think... lol.

Post by **HenryJ** » Sun Aug 22, 2010 6:32 pm

Don't count the Posi-loc as fool proof. Those locking throttle cables can be troublesome at times too. The longer cable is not going to make keeping it operating smoothly easy. I am not clear as to how well it is going to hold up. Engaging it is not going to be as easy for sure. Pulling on the cable and easing forward so that it will engage. Then locking it in position so that it holds. Adjusting the cable. Will the funny shaped end stay on the cable? Will the funny nut stay screwed into the housing? Can it be protected from heat as it passes over the exhaust system?

KISS might better describe the stock system in this case.

fallvitals · Post by **fallvitals** » Sun Aug 22, 2010 6:57 pm

Interesing points. I have done a lot of googling and couldn't find any gripes other then the install on a s-10... If I can find a good deal on one I think I'll do the same as you Brule, and put it on a shelf till the next break down.

Post by **HenryJ** » Sun Aug 22, 2010 7:16 pm

I have followed a few installs over the years. I don't know anyone still running one now. It is not without its own issues as with any mod.

Posiloc

fallvitals · Post by **fallvitals** » Mon Aug 23, 2010 5:54 pm

Well I snagged one on ebay for $62 shipped. Never used missing, two pieces I can easily find at lowes for a couple bucks. Don't think you can beat that deal vs a $200 kit o_0

http://cgi.ebay.com/ebaymotors/ws/eBayI ... 0574631875

Post by **HenryJ** » Mon Aug 23, 2010 6:27 pm

The heat shield can be picked up at an auto parts store. It is heat sleeve tubing.

fallvitals · Post by **fallvitals** » Mon Aug 23, 2010 7:53 pm

I'm hoping I can stay away from the exhaust, I can't think off hand where I would have an issue with it, but you never figure that stuff out till you actually do it. I did find another install thread for this thing. Couple folks said their stock diff cable was seized up on that plastic housing going into the diff. A new one is only $15 from the dealer they also said.

fallvitals · Post by **fallvitals** » Mon Sep 06, 2010 1:55 pm

Well, I installed the Posi Loc today. Im not sure if I will keep it on there... Theres wayyy too much cable with it, so it makes it hard to run. The cable is apperantly a single steel cable, where the stock cable is braided steel. The instructions for mounting the bracket under the dash sucked... I think I had a rough idea of what they ment then decide to do it my way, and their supplied screws wouldn't reach so for now is just mounted to the plastic dash panel

But it engages.. the handle doesnt pull out any where near as far once its installed, I guess thats normal?

Maybe chevy changed their cable because it was just as short as the posi (for any one thats read the complaint on this) When I went to take off the shift housing I couldnt see the spring that holds the cable on. But I worked it free..

Anyways, engaging it takes a lot of strength it seems. I used two hands since I did have a a solid mount for the bracket. After a few test trys I felt it move out a little bit when it engaged. And it easily disengaged. But tried to while driving and its a bit tricky.. sometimes it didnt want to disengage....

I only disconnected the stock cable, put heat shrink over it and zip tied it to the diff axle. I might go back to the stock system, and just keep up with it maintenance wise, Maybe change all the vac hoses to be sure those are good. But it does work...

Im just not sure of my feelings on it yet..

F9K9 · Post by **F9K9** » Wed Sep 08, 2010 5:21 pm

Maybe joining the TX ZR2 board and PMing Miles there will help you with that conversion?