My '87 is not engagning 4WD. It is used only for winter plowing and sits all summer, no problems last year. Lever moves from 2WDH to 4WDH and 4WDL no problem, in 4WDL I can tell the back wheels are engaged in low gear. But the front wheels don't engage and the "4WD" light on the dash does not come on.

This is a REAL problem next snowstorm. Hopefully it is something simple. I have a shop manual for the truck, but it does not have a good troubleshooting section.

I'll go check fluid levels now.....

TIA

JH

 

Check for vacuum at the front axle when 4wd is engaged.
Raise the truck and check if the front drive shaft is turning when in 4wd.
Are you sure it is not ingaging,bad bulb?

 

Thanks, I'll check vacuum lines.

I tried to push a little snow today and in 4WD only the back wheels were spinning on the ice. So I don't think it is engaging....

JH

 

Okey doke....

I spotted a rusty vacuum servo on the front axle with vacuum lines attached to it, touched it to see if the lines were hard/cracked, and it fell off in my hands (very rusty truck)..

Any parts dealers online that would have such a thing???

 

Crap. Just watched the 11pm news, more snow tomorrow night.

What can I do to hard couple the axle? If I take off the CAD housing and fix the fork to the engaged postion will that work? What will happen when I shift the transfer case to 2WD? My guess is that the front driveshaft will not be driven, but the front axle will be locked resulting in the typical hard cornering issues. I can deal with that on the snow....

TIA

JH

 

Put a vacuum pump on it and check if it engaging,if it is, run a switchable vacuum line to it to operate it manually,they also sell cable operated kits,I put one on my jeep,then you can run a locker up front and have 2,3 or 4wd.

 

Well here is an update in case anyone else comes along with a similar problem..... BTW, I restore vintage VWs and like working in my shop, but not only is that damn truck too big to fit in there with the plow on it, I really don't like working on it that much.

3+ hours surfing the internet and I learned all about the little actuator, the fact that it is troublesome and also that you really can't get replacements (any leads would be appreciated). I found the Posi-Lok product, but found it to be a little expensive for a pushbutton cable mod.

Somewhat apprehensively, I decided to pull the mech out yesterday and see what I could do. I was pleasantly surprised that it was pretty accessible from the left front wheel well with the wheel removed. I had envisioned spending the day on my back on a creeper digging rust flakes out of my my eyes...

All of the connections came off of it easily. One bolt was really tight, so I heated the area with a torch a bit first, afraid that I would snap it off.

The nipples had broken off nearly flush, but the cannister looked ok, just really rusty. I cut the nipples flush with the Dremel, and tested the cannister with a blowgun and 20 psi of air in the holes. The fork moved perfectly.

So I came up with the bright idea to solder some brass tubing on the holes. My local hobby store had 1/8" brass tubing and I reamed out the holes with a 1/8" bit. I did some surgical dremel work on the area around the holes to get clean shiney metal, inserted the 1" pieces of tubing about 1/8" and used a 40 watt soldering iron, concentrating the solder first on the cannister metal first. The solder seemed to "take" to the cannister and tubing real well.

Another trip to the local Autozone for some tubing splices and clamps, and rifled my box of tubing for some real skinny stuff to fit on the brass tubing. I hooked it up to the lines in the truck, laid it on the knuckle, started the truck and shifted the transfer case to 4WD. It worked like a charm.

Bottom line is that I don't expect that hack to last forever. So I would still like to come up with another solution. I would rather use a vacuum solution than a cable. I wouldn't mind getting another housing/fork set up to mod, and keep handy until this one breaks.

Anyone know of any kind of "universal" 2 sided vacuum motor that I might be able to use??

quad4x4.com lists a new kit, but says they are out of stock. Dan there says he knows of no other sources. I'm sure I could rig something up to work if I could find an acutator about the same size. Barring that, I'll come up with a cabled solution. I think there is a bit of room under the dash for one more gizmo........


JH

 

Have you tried the Dodge dealer? I was able to purchase an NOS vacuum setup from the dealer for my '87 W150. I'm afraid that was 4 years ago but there may be one collecting dust on some dealers shelf. It's a crap shoot though. Some parts counter guys are too lazy too search for you. Let me know if you need a part number for it.
Because of the corrosion and rust, when I rebuilt that whole vacuum assembly, I replaced the steel cover bolts with stainless steel bolts and washers, sourced at the local Ace Hardware. The cover gasket and fork and shaft parts may still be available from the dealer.
A failing vacuum axle disconnect is the most common problem that crops up on the 1st gen Dodges when the 4x4 is not working properly, especially in the rust belt.. Next would be a broken axle shaft or a u-joint.

Tim

 

Yea, I called the deal and they can get it for $170. Apparently you can also get it from
www.directpartsconnection.com

For $120. Part number I found is 4137725, so all is good. I also have a lead ona used one for $60. I get one and just run this one until it fails (of course my hack will never fail now, if I have a spare in the shop.....)



Thanks for all the help....