well, i couldn't get the bolts out with an EZ-OUT and wasted waaayy too much time trying. i was able to drill out the old bolts (one slightly off center) and then i enlarged the bottom 2 holes of the CAD cover and put it back together with no leaks.

the bad news... i tried testing out the rebuilt CAD to see the fork move. i started the truck, put the trans into neutral. when i attempted to shift into 4hi, the transfer case started making a grinding sound. i never actually got it into 4hi. i've never had any issue with 4hi before.

last week i had the truck at a mechanic and asked him to help diagnose my vacuum system to see if i have another vacuum leak somewhere. i'm getting vacuum at the CAD but i don't think it's anywhere near 17". he mentioned that he had adjusted the transfer case shift linkage "a little." yesterday was the first time i'd shifted the transfer case since being at the mechanic.

i dropped the truck off at a transmission shop this a.m. i'm having no problems whatsoever in 2hi. in fact, i just got back from a 250 mi. road trip to the farm and the truck drove great. i'm hoping that it's something as simple as the shift linkage. i don't know what i'm going to do if it's hosed.

if the t-case checks out okay and my 4wd is still no working then i think i'm going to skip the vacuum system and buy the posi-lok system. i've wasted too much time and money trying to get the vacuum system to work.

argh.

 

If you have a vac leak some where else, a Posi-Lok isn't going to fix it. You'll still have a vac leak.

 

update:

i had a couple problems and unfortunately my transfer case was the main culprit ($$$). i had to get the t-case overhauled. the good news is that the t-case was in pretty good shape. definitely expensive enough but could've been worse.

while at the trans shop, they opened up the CAD again to verify the fork moved the collar over the axle. it does indeed. the shift motor shaft pushes in the switch but just barely falls short of pushing it far enough in to light up the 4WD light. i only tried it a couple of times. 4WD definitely engaged but the light didn't.

i'm going to put a vac gauge on the lines at the CAD this weekend to see what it's pulling. there may or may not be a small vac leak somewhere between the t-case and the CAD. i'll see if i can track it down but at least 4WD is for working for sure.

still considering the posi-lok in the future.

 

i don't recall if the position of the stock 4wd light switch is adjustable or not. if it is, screw it futher in or out where the fork/collar can trip it. if its not adjustable, then your fork is not moving as far as it should, either due to low vac or sticky diaphragm shaft or misalignment of the 2 axle halves. with the cad removed you can push the collar back and forth with your fingers. if it binds up and doesn't slide easily, the vac motor will also have trouble with it.

sometimes the shaft or collar develops burrs that bind it up.

 

SUCCESS!

i checked every single vacuum line point in the entire 4x4 vac system and i finally(!!) tracked down the source of my vacuum leak. turns out the port for the vac source line (white/gray) on the rubber 4-port vacuum line harness that plugs into the transfer case was leaking while connected. over the years, that port looks like it has expanded. as a temporary fix, i put a wide zip tie around the rubber harness and tightened it so that it serves as a clamp. i went from getting very weak vac at the CAD to about ~20 inches of vacuum.

4WD, and the light, now engage and disengage promptly and properly. i would like to find a replacement vacuum harness but the zip tie clamp is working for now.

here's the laundry list of everything i fixed/replaced:

- new 4WD indicator switch (probably wasn't necessary)
- new vacuum switch on the transfer case
- replaced rusted, broken CAD shift motor. replaced e-clips and fork shoes. snapped bottom 2 rusted bolts on the CAD cover and spent all day trying drill them out. did a poor job on one of those bolts.
- transfer case pulled and completely overhauled. that one hurt... but the rebuild fixed the intermittent vacuum switching, 4x4 engagement and grinding gears. oh, and the transmission tech repaired the poorly drilled out hole in the axle cover that i messed up earlier for free.
- broken vac line near the intake (fixed my cruise control)
- broken vac line near CAD
- clamped leaking vacuum line harness at the transfer case

i pretty much rebuilt my entire 4x4 vacuum system. now i'll know how to fix it next time. thanks for everyone that helped me along the way.

kb

 

Congrats on getting it fixed. I am sure that others will benefit from your thread!