Archived Ice Cold CAD

[Eco Rednek]

Any one have an explanation as to WHY the central axle dissconnect sometimes does not work in the cold????



Mine seems to fail below 20 or so. . I chased the VAC signal to the disc shaped actuator on the axle where the vac lines connect..... good suction. Still no 4wd..... ? Next, I took a heat gun to the disc shaped actuator and warmed it up good, 4wd works perfect... .



I have read so much about the fact that this system is known to fail in the cold (when it's most needed) but never any explanation as to what causes the failure.



I plan on installing the posi lock cable but would rather not shell out the $$$ right this minute if I can find a way to make this crippled ship sail a little while longer.



Cold Snowy rocky mountains, winter will be here till june, 2wd diesel truck not good!!!!!!!

 

[Steve St.Laurent]

I've never heard anything about our CAD disconnects not working in the cold. What you hear about usually is the Chevy system which uses a heated element. I've never had problems with my CAD disconnect not working in the cold - down to minus 30. My guess would be that there is moisture trapped in there that is freezing causing your trouble. Now how to get it out I couldn't tell you. Maybe pull the vac lines and heat it to boil the moisture out? Hopefully someone else will chime in with a good idea.

 

[DieselTweaker]

try some air line antifreeze to help prevent it from freezing over

 

[JTryles]

try some air light antifreeze to help prevent it from freezing over

How about a shot of that "Air Brake Antifreeze" they sell at truck shops?

 

[Eco Rednek]

Thanks for the help...



Should I put liquid anti freeze into the actuator Through the vac connections?



When I was down there today, I hooked a spare vac line to both ports and tried to suck out moisture... ... ..... nothing.



What happens inside that disc shaped vacuum servo? What process would frozen water interfere with? Is it a good Idea to introduce liquid(antifreeze ) into that system? Sorry to be so particular? I cant bear to not fully understand. Don t know much about how vacuum systems work.

 

[JTryles]

Thanks for the help...



Should I put liquid anti freeze into the actuator Through the vac connections?



When I was down there today, I hooked a spare vac line to both ports and tried to suck out moisture... ... ..... nothing.



What happens inside that disc shaped vacuum servo? What process would frozen water interfere with? Is it a good Idea to introduce liquid(antifreeze ) into that system? Sorry to be so particular? I cant bear to not fully understand. Don t know much about how vacuum systems work.

Well, if I understand correctly a servo is, basically, a small motor... water in there freezing would cause it to not be able to move whatever internal parts it may have. It sounds like your going to be needing a new servo anyway, so what harm could come from trying a little "break fix" by injecting a small amount of some anti-freeze type substance in there?

 

[Woodenhead]

Mine was working intermittently and not working at all when it was cold. Turned out the CAD had a small/slow leak in the diaphragm and the vacuum switch on the transfer case was sticky. The CAD solenoid may just not have the power to move far enough when it's colder/stiffer or the vac. switch may stick worse when it's cold. My guess is since yours worked fine when a heat gun was on it you may need a new solenoid but check it for leaks.



Dan at Quad 4x4 changed my CAD solenoid and vacuum switch while he had my truck and it worked great through some pretty cold weather last winter and is ready for the next one. I asked him about the manual cable for the CAD and his comment was if the first solenoid and switch worked good for the first 8 years why change it (made sense to me).



Mike

 

[Ol'TrailDog]

pwknapp had problems with his CAD not engaging when it was cold. Some times it do that in Pinedale, WY :-laf



He had a cable activated system that he got from a Rock Rabbit or Rok Rabbit???? It was a Loc something or the other. I emailed him earlier to get my memory refreshed about what product it was because it looked pretty slick, but haven't heard back.





pssst... I think he is avoiding me.

 

[WMowat]

The bushings for the insisde of the axle shafts are probally starting to wear as well, when they do it is difficult to get into 4wd, Pull off the servo and look at the axle ends, there is a bushing that fits into the one axle to guide the lock over the one onto the other axle, if it is definately the servo you can buy a cable operated one, I just can't remember the name of the company. Some one else on here might know. Its basically a pto cable and housing that allows you to select manually. It also works great for 2wd low. Sorry about the confusing explination, hope it helps

 

[Eco Rednek]

Thanks for all the help. I broke down and ordered the posi lock cable system. .

Called the local dodge dealer, 230. 00 to replace the VAC motor... . 180. 00 for the posi lock. . no brainer, not going to replace a flawed design with the same flawed design.

I can t go to work today cause its snowing and my jobsite is up a steep hill.

A little bitter.

 

[Ol'TrailDog]

Mind if I ask where you found it for $150? Most sites I've seen are asking around $200.



Edit: Nevermind, my eyes must be getting older than the rest of me. You said $180.

 

[ABeattie]

I had the same thing happen to my jeep { basicly the same setup } and I had change the lube and just clean the slide and fork. I think the lube was just getting gummy. Worked for me.

 

[Eco Rednek]

Went ahead and installed the 4x4 posi lock cable yesterday, pretty straightforward, but very unpleasant groveling around under the truck in 18 degree temps.



Pulled the old vac CAD off and sure enough, it was frozen solid! Could not move the fork at all. . After a quick ride on the woodburning stove, it thawed and moved back and forth easily, when I set it down on the table, the vac motor puked out about a tablespoon of water!! Problem solved.



Obviously, I went ahead with the cable install, but perhaps others with frozen 4x4 syndrome could try pulling the CAD and drying it out..... Dont know how or why there was water in there, but it was a considerable amount... .

 

[Hvy-DCZ]

Eco Rednek (love the handle, not too many of us around),



Thanks for closing the loop on this. So many just leave us wondering about the root cause.



Happy motoring. I'm very interested in adding the manual posi-lock cable, but too many expenses right now. Not a crisis at the moment. Really good info on what your issue was w/ the cold temp - non-functioning CAD.



Cheers,

Hvy

 

[Eco Rednek]

DCZ,



Thanks man,



Y know I just flew up to portland(salem actually) where I bought my truck Nov 4. I dont think she s ever seen cold like she s seeing it now in her new home 15 miles west of the continental divide at 8300'. Gonna take some gettin used to... .