I tried posting this earlier but it didn't seem to take so I will try again.
I bought a 95 Ram Cummins 4x4 5spd last week. Drove it home 150 miles in 2wd no problems. Put it into 4wd lo range to back it up and park. Then put it back into 2wd and shut it off. Next morning I started off to get it inspected and began hearing and intermittent grinding noise, like gears attempting to mesh as I drove along in 2wd. It would occur in any gear at any speed. It came and went without any apparent pattern. The sound seemed to be coming from the tranny/ transfer case region but I know sounds can telegraph from other places. The transfer case was replaced before I bought the truck and judging by the other repairs done to the vehicle it was probably done right. A buddy suggested that maybe one of the auto locking front hubs is beginning to fail and is attempting to lock even though the transfer case is in 2wd. I am not driving the truck for fear of doing damage until I can figure out what is happening. Any ideas on where or what to look for would be appreciated.

 

First thing that I would do is check the fluid in the transfer case. They take ATF and are a little prone to leaking. Mine got a little low once and would make some noise. Also wouldn't hurt to check the levels in the front and rear axles. Should be about 3/4" below the plug. Good luck.

 

Auto hubs?

these trucks dont have auto hubs, they have a central axle disconnect, its kinda simple, the CAD as it is abbreviated works or it dont, if you were moving while engaging the 4wd and u heard the noise from the bottom right side, it was probably the CAD, if you heard it sort of under you then it was probably the Tcase, in either case, i would check those things first, the axle fluid levels, and the Tcase level, i know mine leaks a bit... but i keep up with it and change fluid on it every third oil change and its good to go... Overkill, but i do use my 4wd in sand quite a bit....

Rick

 

Id check the linkages on the shifter / transfer case to make sure something hasnt bound up and is trying to engage the case halfway.
Also Id pull the CAD cover on the passenger side front axle to make sure the collar that connects the axle isnt part way engaged.
If you catch this early and fix it it shouldnt be bad.. If you leave it, it could get real bad. I had to replace a front diff once on an old chevy because a 5$ vacuum switch had left the thing half way engaged in 4wd and the gears chewed each other to shreds =(

 

Thanks for the hints.I all checked all fluids and all OK, transfer case /shift linkage is smooth and positive. The CAD unit , does not look to have a removeable cover, the unit I have is attached to the rt frt and is bolted with 4 bolts . It has a round metal fitting on the outboard end with two rubber tubes coming out into a fitting with red and black wires that heads out. On the inboard end is a hex fitting with a 2 wire elec connector that also heads out. Am I missing something.?

 

yes it does

those four bolts that you see, are 7/16 i do believe and can come off. What you are seeing is what needs to be removed to check the CAD, the rubber lines are the vaccum lines that engage or disengage the 4wd, and the upper rubber line is a breather line,and the electrical connections are for the 4wd indicator in the cab of the truck, now its been a while since ive messed with my CAD, ever since i went and posilocked it i forgot about it, but im sure that those indicators are for the 4WD on the truck..

You can remove those four bolts, and everything comes off easily and you can inspect the CAD, you will see in there that it is a fork that moves the little collar which will give you the 4wd or 2wd due to vaccum pressure, it all makes sence on how it works once u remove the four bolts and check it out..

Rick

 

Thanks Rick
I am going back out to the garage now and check it out

 

Should there be oil behind the cover because as I loosened the bolts it started dripping out! I tightened it back up and posted this.

 

yes there is oil in it. when you put it back toghther loosin the indicator switch on the cad and fill the cad up VIA the breather tube. then tighten the indicator (allow's vent)

 

What type of oil do I refill it with?

 

gear oil, 80w90 or to your preference. Also to back up what 007 said, posilocking is a great choice. And he is correct with his decription. I'm willing to bet when you pull it apart you will see it is still locked in. You might have a vaccum leak or a bad CAD that is not wanting to disengage it. When you get it off and it looks like it is disengaged, you might have someone shift the truck in/out of 4wd and see if it moves. Remember the engine has to be running or you will have no vaccum to move the actuator.

 

Can I do that 4wd in out test with the unit open but connected? Whats involved in posilocking my truck?

 

Should be able to. 4x4 Posi-loc removes the vaccum shift actuator and makes it cable shifted. Check out their web site.

 

Istheir website posilock.com?

 

Took of the CAD cover fired up the truck and had my wife move the transfer case lever from 2wd to 4wd and back a few times. The fork in the CAD moved back and forth accordingly. So I am back to square one as to tracing this noise. I just put a coat of paint on my muffler and tailpipe but when it dries I am going to give the truck a test drive just to see what is what. Will report back.
Thanks