Greetings, I'm looking at purchasing an 86 Ram 4x4 318 auto. Truck is in fantastic condition but when I was test driving it I stopped near the owners house put the truck in reverse then put it in neutral and put it into 4 wheel drive. Had to put a fair amount of pressure on the floor shifter to engage but it went into both 4H and 4L and the dash light came on. Problem was I could not get it back out of 4 wheel drive, even when the lever was pushed back to 2H the dash light remained on and you could hear the whir of the front dif. After returning to owners house he couldn't get it back to 2wd either and when he'd move the truck I could see the front driveshaft turning. The owner said he rarely uses 4wd so I'm assuming it may be a sticky linkage or something stuck. Since I have never owned a 4wd truck before I'm looking for some advice as to how serious this problem might be? Thanks in advance for your replies, Steve
Speed Dragon
01-14-2008, 10:34 PM
Probably just the vacuum switch for the front axle froze up, easy fix provided you can find a good one used, or a new one. I think they sell new ones still.
In other words, the t-case in in 2wd, but the front axle is still engaged. The shift lever was probably just stiff from un-use, liberal coating of PB Blaster should free it up.
SVT4CAM
01-15-2008, 07:14 PM
After perusing the search function here and on other Dodgeski sites I think it may actually be the vacuum switch on the transfer case. The little ball in there may be stuck. Since it engaged in 4 wd then the front axle was stuck on engaged but the transfer case was turned off when shifter was put back to 2wd. I would think if it was the vacuum motor being frozen up it wouldn't have engaged the axle to begin with. Does this make sense to you Dragon?
DiverDwnPowrRam
01-16-2008, 11:15 AM
actually Speed may be right...here is why. The diaphram is actually pulled much like your pneumatic airconditioning controls. when engaged the vacuum pulls the switch over and you have 4X4 but due to a faulty switch the vacuum may not be allowed to pull it back to 4X2 and therby keeping it locked and thus still engaging the 4X4 indicator light. I would make sure all the vacuume lines are good, make sure you have a good vacuum ball (drivers side x member) and then look into that axle shift motor.
DiverDwnPowrRam
01-16-2008, 11:19 AM
When i said it is like a/c controls, this is because it uses two lines to pull..one to close one to open...you get the meaning....
Speed Dragon
01-16-2008, 12:31 PM
I was a bit inaccurate, I meant the axle actuator on the front. The vacuum switch is on the t-case, yes. Could be either or, I suppose, however I'd check the actuator on the axle first, A) because it's easier to get to :) and B) seems to me it'd be more likely to be bad, considering it's location.
I'm a little blurry on the auto-engage system on the newer ones, all my stuff has been manual hubbed. Is it a vacuum actuator or the front axle, or an electric motor? I thought there were vacuum lines that ran to it, but I'm not sure.
DiverDwnPowrRam
01-16-2008, 10:57 PM
maybe i confused things..I was meaning also just the front actuator motor...it is totally pneumatic...nothing in my post indicated the t case only because as speed said it is easier to work on.
SVT4CAM
01-17-2008, 06:03 AM
Guys, Thank you for all the replies. I am purchasing the beast and I will pick it up Saturday morning. When I spoke to the owner yesterday he said that the truck had disengaged the front axle by itself while it sat in the garage. (He doesn't drive it because of the price of gas.) I ordered one of the transfer case vacuum switches because that's the cheapest place to start ($14.00 and I can return it if not used. I will keep you posted on the developments. Thanks, Steve
Speed Dragon
01-17-2008, 08:56 AM
maybe i confused things..I was meaning also just the front actuator motor...it is totally pneumatic...Ahh okay. So basically the vacuum switch on the t-case lets vacuum go to the vacuum actuator on the axle when placed in 4wd positions, and removes vacuum when shifted to 2wd? You say there are 2 line to the actuator? Just curious how it all works exactly, for future reference:cool:
