I went snowmobiling the other day and now have popping going on inside my front end when in 4wd and there is pressure on the drivetrain. I believe it is the CAD as I have already jacked up both sides, checked all 5 U joints and turned the driveshaft (Pinion feels tight and driveshaft turns with ease). All U joints look good and have no slop in them. The transfer case has very little slop as well. The only thing left is the CAD. I think the diaphragm inside the actuator has gone bad because I can suck on the side that pulls the CAD over onto the disconnected side and it holds the vacuum. If I suck on the other line, it does not hold vacuum. Is there anything else I'm missing?

You have a CAD?  My 02 doesn't have one.

Mine does... Kinda wishing it didn't right now. Looks like the actuator is going to be 70+ bucks

There is a video that shows how to install a cable that has a lock when turned Napa is where I got mine and you can manually activated. I still plan on doing it but have not yet done it. No more vacuum and you can move a trailer around or what ever in low range without having the front diff locked up

It may not need a new actuator. Pull the four bolts and make sure everything moves good.

Got vacuum in the rest of the truck? Ie: do your heat and ac doors move?

^{You may want to  read my latest findings  on my ball joint thread...  I found some issues  that relates  to  an  earlier thread of mine,}

^{"slow to engage  4X4"}

 

 

^{Was your  popping noise  when in 4X4?  and  was  the   indicator light  solidly  ON?          The  only time  that light  will come on  is  when the shift fork is  COMPLETELY  'home'.}     

 

 

Edited January 19, 201510 yr by rancherman

There is a video that shows how to install a cable that has a lock when turned Napa is where I got mine and you can manually activated. I still plan on doing it but have not yet done it. No more vacuum and you can move a trailer around or what ever in low range without having the front diff locked up

Got  a  POSI-LOK  on the way!    should be here   Tues.

It's  a cable  actuated  shifter.    I think  it  was  about 165 bucks.     A new  vacuum  actuator is 90...  

I pulled the bolts and took the fork/actuator assembly apart. Everything looks good. The collar slides easily back and forth, and the shift fork is not frozen in its own housing. Vacuum in the truck works great. Quickly changes between floor/deforst/face/face and floor. I even checked vacuum down at the actuator and it seems good. Rancherman the light appeared solidly on, but I have a gauge that sits right in the way of the light so I really have to look for it. 

Have you checked your diff oil for metal flakes or anything? if your CAD is fine it almost sounds like the spiders could be toast.

I pulled the bolts and took the fork/actuator assembly apart. Everything looks good. The collar slides easily back and forth, and the shift fork is not frozen in its own housing. Vacuum in the truck works great. Quickly changes between floor/deforst/face/face and floor. I even checked vacuum down at the actuator and it seems good. Rancherman the light appeared solidly on, but I have a gauge that sits right in the way of the light so I really have to look for it. 

hey,  just for giggles,  before you   re install the cad,   stuff  a  rag  back into the opening,  fire up the  engine,  and  visually see if the shift fork is  moving  in and out.  (hook up the vacuum and electrical again)

hey,  just for giggles,  before you   re install the cad,   stuff  a  rag  back into the opening,  fire up the  engine,  and  visually see if the shift fork is  moving  in and out.  (hook up the vacuum and electrical again)

I had already put it back together last night  I live at an apartment complex. I may do this when I get home.

 

Have you checked your diff oil for metal flakes or anything? if your CAD is fine it almost sounds like the spiders could be toast.

Oil looks perfect. I changed it along with both front seals this summer. I don't think the spiders can be toast because I can spin the driveshaft in 2wd and it spins free as can be. Not chunky or rough like I would suspect it to be with broken gears. 

I just remembered somethng that may be the cause. My daughter's truck acted like yours. Hers was the mode fork in the transfer case. The plastic tabs wore out and the fork was about 1/2 wore also. It would sometimes go into 4WD and other times not. It is not hard to fix, but would be a PITA for you to fix in a parking lot.

I just remembered somethng that may be the cause. My daughter's truck acted like yours. Hers was the mode fork in the transfer case. The plastic tabs wore out and the fork was about 1/2 wore also. It would sometimes go into 4WD and other times not. It is not hard to fix, but would be a PITA for you to fix in a parking lot.

So hers was slipping inside the transfer case??

Yes sir. It sounded terrible when it did too!

I found out on my 1996 Dodge the CAD unit had a vacuum leak in the diaphragm. So this made it weak to pull in both directions and typically had lag. I replace mine the problems are gone no issues. The NAPA vacuum motor was like $90 bucks but came as a full rebuild kit for that CAD unit. 

I found out on my 1996 Dodge the CAD unit had a vacuum leak in the diaphragm. So this made it weak to pull in both directions and typically had lag. I replace mine the problems are gone no issues. The NAPA vacuum motor was like $90 bucks but came as a full rebuild kit for that CAD unit. 

I'll check that out Mike. It is confirmed it's the cad. I had my brother drive the truck while I listened and the popping is coming from the CAD area. Luckily it's not the transfer! I didn't think it was because I had it all torn apart this summer to re-seal it. Everything inside looked great!

Take a vacuum hand pump and put a good vacuum on one port at a time and watch and see if the vacuum falls if so the diaphragm is leaking.

next time you  have the  cad  off,    push up and  down on the  end of  the  shaft  (the shaft  going out to the   u-joint)        It  should  be    near  solid  to  the  inner shaft. 

 

Wiggle  the  connector  collar too,   it may be blown out

Edited January 21, 201510 yr by rancherman

Mike I did it with my mouth.... on the side that pulls it into 4wd it wouldn't hold anything. The side that pulls it out of 4wd held a vacuum

the side that  didn't hold...     was  the fork still moving,  which gave  the illusion  of it  not holding?    ( once  the   diaphragm  hits the other side,  then  vacuum  would  build)

 

 

another way  to test  would be  to have  the  cad off the axle,  and    put your finger over  the  nipples..   then see if  you can  move  the  fork back and forth.    you would get pressure on one side,  and vacuum on the other.

 

you may have  a   rusted out  canister on one side of the  diaphragm,   which    only works  in  one  direction then.   That's  why  I'd be leary on  even  giving you mine!

Edited January 21, 201510 yr by rancherman