# 2001 dodge ram 4wd wont engage



## singlecabd

sealed up vaccuum lines,lines are not dry rotted,replaced shift accuator,replaced u joints,axles are in great shape,using heavy duty gear oil, when i shift into 4lo and put the truck in drive it jumps from all the torque,but my hubs wont lock,i dont know what else to do


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## 97'sonoma

what were you doing the last time the 4wd worked?


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## singlecabd

97'sonoma said:


> what were you doing the last time the 4wd worked?


 the last time it worked i had to drive it a mile in 4lo to lock it in,then i shifted to 4hi and drove back in to the woods


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## singlecabd

sorry im new to this,i just accidentely put my reply with your question


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## 97'sonoma

well it definatly sounds like a vacuum problem. have you checked the vacuum pump or vacuum actuator that operates the hubs?


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## SABL

singlecabd said:


> sorry im new to this,i just accidentely put my reply with your question


No problem... you clipped the quote. Many times it is good to include the quote with your answer... such as I am doing to make this comment.

Are we talking transfer case or the actual hubs?? Some vehicles do not have front hubs.... my '98 Cherokee is one that does not have them. The hubs are attached to the spindle assembly on each front wheel.... can be manual or automatic.


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## singlecabd

hubs,my shift accuator is what locks in my hubs,i replaced it yesterday,i checked my vacuum lines and they look alright,my truck has seen alot of mud some maybe they are clogged but im not exactly sure,do you kn if theres any was of checking them before i replace them????


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## 97'sonoma

about the best you can do to check vac. lines is take them off one at a time blow them out and put it back on and move to the next one. try blowing through them by mouth to see if they are clogged but I've never had vac lines get mud in them because they are closed circuits, if theirs mud in them somethings broke.Also is the front drive shaft engaging. try puting your truck on jack stands all the way around and engage 4wd with it runing and put it in gear just to make sure its not your transfer case instead of youre hubs cause if your hubs lock but trans case doesn't it my seem opposite.


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## singlecabd

yah,i will try that today,im thinking that also maybe the coller that slides back and forth between the passenger side axle shaft and the intermediate shaft may not be lining up properly and something is in a bind,but when i shift between 4hi and 4lo i can feel the transfer case engaing,also ima check out the vacuum lines


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## 97'sonoma

cool let me know what you find and ima do some studying on this problem.:wink:


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## singlecabd

ok,i just put the truck up on jack stands and put it in it in 4lo and 4hi with the transmission in drive and reverse,the front tires didnt spin at all but the driveshaft leading to the front axle was spinning fine,so i kno its not in the transfer case,thank goodness,and i just dont see where there would be a leak or a loose vacuum line,and i had just replaced the accuator on the front axle.but i did some research and i found out theres a control switch on the transfer case,is there anyway it could have gone bad?


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## singlecabd

also i found out my trucks 4 wheel drive doesnt lock in by the hubs it uses the shift accuator to slide a shift collar back and forth to lock it in 4wd


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## 97'sonoma

can you see the actuator and collar if so see if the collar has any cracks in it. and clean the mud out if there is any and check all linkages and see if any are bent.


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## 97'sonoma

oh hey did you check the fuse for the 4wd?.....


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## singlecabd

the linkages are all straight,ive never got my truck stuck on anything or damaged the undercarriage in neway,and when i was replacing the accuator i was sliding the colla back and forth and it would slide over the intermediate shaft,i dnt kno if it was cuz the axles werent lined up or what but it didnt wana line them up,and i didnt know i had a 4wd fuse.ima check that out


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## 97'sonoma

ok hope and prey itsa fuse "cheapest route"


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## singlecabd

i nvr found a 4wd fuse,ima take my accuator back out when i get a chance and jack my righte front tire of the ground,and see if i cant line the axles back up again and get it to lock,and then ima test my vacuum pressure,the pump on the transfer case may have gone bad,this is so aggervating,theres nothin on that truck i cant fix but this stupid problem


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## wolfen1086

I feel your pain man my S-10 Blazer has vacuum front diff and its a pain in the rear when it decides it doesn't want to work.
If its set up like my Chevy then theres a vac switch on the transfer case a few vac lines and a actuator that engages the diff lock, so if everything else is ok then it could be a bad diff set.


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## singlecabd

ima try puting a new vacuum switch on it if that dont work i may actually pay someone to look at it


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## wolfen1086

If your in the Hampton roads area I work cheap


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## singlecabd

sry man,deepsouth alabama.lol


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## wolfen1086

Well that explains a lot  got a 4wd and wanting to fix it yourself  Its gotta be a southern thing huh?


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## Spanky4848

What was ever the outcome of your situation? I have 2001 Dodge ram and im having VERY similar problems. I just found this thread and will be trying all of these things this weekend.


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