Hey all new to the site first post so go easy on me just bought a 1996 2500 plain stock 12v . bought the truck with 190,000 on it and 4x4 isnt working the vac lines are not hooked up correctly i think. From the front axle the two smaller vac lines run down the frame rail to the trans where do they hook up to?? then also the one big vac line from the front axle 4x4 locking piece where does that hook up to mine runs up by the turbo and is plugged. I checked around for a diagram but I could not find one searched the owners manual also. thanks

 

the ones that come off the frame rail go to the top of the tcase and the actuator on the front axle. the big one off the axle is a breather if i'm not mistaken. i'm guessing you have a vac leak somewhere. hope that helps.

 

that helps a ton now i have a place to start thanks man

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OK i just got done messing with the vac lines The two vac lines that run down the fram rail Hook up to the red and black vacc lines coming from the top of the t case is that correct? the red line has vacc pressure but that black vac line does not.

 

that is correct. start your truck and put it in 2wd and check which one has vac. then put it in 4wd and the other one should have vac. if it does not switch you need to replace the switch on the top of the tcase. if it does switch either the the diaphram on your front axle or the collar thats in the axle housing under the diaphram is cracked/broken. hope that helps too. let me know what happens

 

you are the man! thanks I appreciate it ill let you know what happens this explains my high crank pressure

 

Maverrick you get the 4x4 handled?

 

I got vaccum in one of the lines when in 2wd then i switch to 4x4 and i get vaccum in the other I guess its the piece that locks that axle in the front when in 4x4. also vaccum line that comes off the trans left side that is not hooked up is this a breather also.

 

not 100% positive but im pretty sure its a breather. you should check the diaphragm when you take it apart. it could either be the collar that locks it up or the diaphragm that moves the collar. its pretty simple when you take it apart you'll see where everything is. good luck

 

thanks man I think that line is a breather the end piece is not flanged or anything but im going to rip that piece apart tonight just washed the truck and water in fuel light is on got to go drain and clean that up tonight going just get a new filter while im doing it. then valve cover gaskets and ill be good to go for another couple k thanks for your help ill let you know how that piece looks inside

 

if you need more help post some pics