1991 jeep wrangler 4x4 wont work?

Answer 1

The most likely culprit on the 87-95 Wranglers is that funky vacuum motor that sits on the passenger side of the front axel. If you do not engage the 4WD frequently, it freezes up. I have taken the motor out & squirted it liberally with PB Blaster (or another good penetrating oil- NOTE_ WD-40 will probably work but is not a penetrating oil but a water dispersant- penetrating oils work better as they are designed specifically to get past the gunk to loosen things). Then work the action back & forth many times to free the shaft. I always engage my 4WD now when I start my beast to keep the shaft moving. The shaft moves a fork that rides in a slot on a sleeve that links the center & passenegr parts of the axel together to kick in 4WD. To check if your Xfer case is engaging, put vehicle on 4 jack stands & make sure they are solid. Then start the Jeep & engage 4WD and have someone look at the front drive shaft on the driver's side. If it is turning, the Xfer case is working. Another option is to replace the vacuum system with a manual cable system ( I will go this route eventually). Posi-Lok makes a nice set up but it also costs just Iver $200. Another way is to search for a home made cable system that can be made for about $30 if you are handy. If not, then go the Posi-Lok route.