4 wheel drive not engaging - what could be the problem?

[MudPuppy]

Still looking for an SX/4, ran across one that seems to only have this one problem...
The cars 4x4 system needs some work the car drives in 2 wheel drive. but when using 4x4 the trans axle does not stay engaged.
Would running new vac lines for the 4x4 fix the problem?
Or is it something else?

Is it hard to find all the vacuum lines for an SX/4?
How much does it cost for all the lines?
_____________________________________________________________________________________
This particular car has the following:
4.2 liter i6 with an offenhauser intake converting the car to a four barrel.
edelbrock 600 cfm carburetor (car starts great and runs a little rich but with new jets or carb problem is solved)
new HEI distributor
transmission is an automatic 3 speed no over drive
133k miles
all factory smog parts have been removed (straight pipe exhaust too)



What do you think?

[Draekon]

The vacuum lines should just be generic vacuum tubing that you can get from an auto parts store.  I've never looked at the tcase vacuum hoses, but I know at least the front diff are made up of generic hosing, so I assume the tcase is the same way.

Also, a 600 cfm carb seems a little big for a 258.  You might consider looking for a slightly smaller carb if you buy it.

[IowaEagle]

If you can't find a good used set then you can make your own.  The steel manifolds do present a problem.  They may look OK, but can have pin holes.  I think one of the major AMC vendors might have the plastic lines.

[MudPuppy]

Would be awesome if it is just the line over the manifold.
And he did state "the car drives in 2 wheel drive. but when using 4x4 the trans axle does not stay engaged.", so it is getting some vacuum for a period of time but then loses it.
My hope is that it is an obvious hole or crack.
I could see going through each individual line to detect a small pin hole would prove to be a pain. Is there something that could be used to run through the lines quicker? Maybe some type of water/soap spray that would shows up as bubbles when a leak is detected.
But so far this 4WD problem and the car running rich seems to be the only problems that he has stated so far.
Will dig further and get more info, then to determine if it is worth it.

[jim]

Assuming transaxle means the front axle, in my opinion it would be simpler to lock the front axle, making it shift on the fly, rather than messing around with vac hoses.

[Draekon]

You can get a handheld vacuum gauge and check the vacuum at the end of the hose where it would plug in to the transfer case.  I don't know what the specs should read, but maybe someone else can chime in on what reasonable values would be.

[runs.like]

I'd climb underneathe with a 9/16 wrench and manually engage the 4x4- check the eaglepedia for detals.  In my wagon the vac lines are a mess and looking for vac leaks in a 23 yr old mess of lines doesnkt seem realalistic to me so I engage it from below every time...4x4 in winter, 2 in summer.  I am planning to make it a mechanicl linkage using a push/pull cable like jeep guys and some other members have done in the past, I think someone did a write up about it at one point

[Draekon]

I'd climb underneathe with a 9/16 wrench and manually engage the 4x4- check the eaglepedia for detals.  In my wagon the vac lines are a mess and looking for vac leaks in a 23 yr old mess of lines doesnkt seem realalistic to me so I engage it from below every time...4x4 in winter, 2 in summer.  I am planning to make it a mechanicl linkage using a push/pull cable like jeep guys and some other members have done in the past, I think someone did a write up about it at one point

There is a writeup in the eaglepedia
http://www.amceaglenest.com/~iowaeagl/guide/index.php?title=Cable_Operated_Transfer_Case_Shifter_-_Joshpit2003

[MudPuppy]

Assuming transaxle means the front axle, in my opinion it would be simpler to lock the front axle, making it shift on the fly, rather than messing around with vac hoses.

Hmm, yes I would rather do that. Do we have a "how-to" write up on doing that anywhere?
*goes to do some hunting*

[jim]

We do.  I think it may be in the 'pedia.
After losing my 4x4 in the snow winter before last - the 83 went into 4x2 and then 4x0 -
for this winter I not only put it in 4x4 underneath, I wired the lever in place.