Re: URGENT- Vacuum Eagle won't engage 4WD

A: One of the shifter motors is seized up or the vacuum lines have come 
apart someplace. First spot to check is the dash switch for vacuum with the 
motor running (one of the 3 connectors will have vacuum) If not, the problem 
is bewteen there and the rear vacuum port on the intake. (often a split or 
plugged vacuum ball) Going from there (once vacuum to the switch has been 
achieved) with the diagram on http://209.238.200.129/gw/vac/eagle/EagVac.pdf 
you can see it goes to a set of check valves next to the motor. Engaged 
makes the vacuum flow to the front axle first, then engages the vacuum motor 
on the Tcase. Disengaged makes the Tcase shift to 2WD and then unshifts the 
front axle.
   My suggestion is to kiss the vacuum front axle system goodbye and either 
permalock the front axle, replace the 2 piece RH shaft with a 1 piece one 
(all NP119 Eagles and '86 up got them) IF the seal is in the same place, (it 
is with the XJ axles) OR get the same front axle posi-lok cable system used 
with the XJs aftermarket (Even NAPA sells them!) and make the minor mods to 
make them work or build your own.
   I still have the complete third member from an '80 Eagle with 3.08 ratio 
in my for sale pile (but it's heavy and shipping from Seattle would be 
rough)
   Once the front axle situation is under control (I even saw one where they 
engaged the axle, then filled the vacuum motor with silicone to force it to 
stay engaged.) you can hook the hoses from the dash switch directly to the 
shift motor on the Tcase, and cap off the third line (vacuum cap and glue 
works) that is closest to the moving rod. Then just remove the pin on the 
dash switch (it's a simple circlip and spring to take out) and you'll have 
shift on the fly. (WARNING! Do NOT remove the pin until you have the front 
axle permanently engaged or you will hear horrible noises when you flick the 
switch. I saw one diff engage as they slowed down, tear the mount off the 
side of the engine and beat the oil pan and floor badly with the 
driveshaft!)



From: Jesse <j2sax@xxxxxxxxx>
Subject: URGENT- Vacuum Eagle won't engage 4WD
To:

Well, now I remember why I liked the full time system
in the early models!  I have an 83 Eagle SX4 258 Auto
that won't engage the 4WD.  I inspected what I could
see of the myriad tiny hoses I could find, however,
nothing obvious popped up.

First, are there any common problems to look for?

Secondly, I have a vacuum pump... what is the easiest
way to use this to engage the 4WD and just leave it on
(this car will not see the highway for a long time as
I only will use it on the property until I sell it)

Thanks and have a great week,


Jesse