4wd Problem. Any mechanics here?

[MDM]

Hi All. I've got a 98' Ford Ranger that won't go into 4wd. It is a vacuum engaged system. The dealership told me it would be one of two things. The switch on the dash or the engaging motor. I replaced the switch on the dash and that didn't fix it. The said the motor ran around $400.

I've heard rumblings from others that it could be just a vacuum line is bad. I bought a Chilton repair manual and it is absolutely worthless in diagnosing the problem. It just says to disconnect the vacuum lines and then shows you how to replace the motor.

Anyone have any experience with this or in diagnosing the problem?
Thanks.

 

[Phils]

If Ford was using the same motor to engage 4WD that they used earlier in the nineties, the most likely cause of your problem is a broken nylon pin in that motor assembly.

Most shops will sell and install a new motor for you $$$$

Our local tranny shop takes the motor assembly apart and installs a new pin, made out of speedometer cable guts (one cable makes many pins, of course). It's been over 5 years so I can't remember how much but it wasn't very expensive, especially when compared to a new motor.

I can get phone numbers if you want to talk to our shop if your local shops disclaim any knowledge of this procedure. If you had to have them mail you the pin (from CA) it may even be a repair you could do yourself. It didn't sound too difficult to make the pin and the labor cost wasn't much so it may not even be difficult to change it.

Phil

 

[cp1969]

Hi All. I've got a 98' Ford Ranger that won't go into 4wd. It is a vacuum engaged system. The dealership told me it would be one of two things. The switch on the dash or the engaging motor. I replaced the switch on the dash and that didn't fix it. The said the motor ran around $400.

I've heard rumblings from others that it could be just a vacuum line is bad. I bought a Chilton repair manual and it is absolutely worthless in diagnosing the problem. It just says to disconnect the vacuum lines and then shows you how to replace the motor.

Anyone have any experience with this or in diagnosing the problem?
Thanks.

Your truck uses Pulse Vacuum Hubs. Did the dealership not think these could go bad? They do...with regularity. You can diagnose this by

1. Putting the truck in 4wd and raising a front wheel off the ground. With the transmission in gear (if manual; Park if an automatic), you should not be able to turn the wheel.

2. If you can turn it, look to see if it's axle is turning. If it isn't, the hub is not engaged.

3. If you can turn the wheel AND it's axle turns with it, look and see if the driveshaft is turning. If it is, you have transfer case engagement problems.

4. If the wheel turns and the driveshaft stays stationary, then the other wheel's hub must not be engaged--it's axle will be turning in reverse.

5. Clear as mud?

You can buy an aftermarket set of manual hubs. If my computer hadn't crashed and I lost it, I would have posted a PDF that tells you how to convert the non-working PVH to manual. It is very simple. You end up acting as the vacuum diaphragm and locking and unlocking the hubs with your finger, through a hole you drill in the outer portion of the hub cover.

At any rate, go over to the Ranger Power Sports forum. I think that's the name of it; I lost that bookmark, too. Or the Ford Truck Enthusiast site and do a search there. It was at one of those two places where I got the PDF and there is a lot of good info there about Ranger vacuum hubs and 4wd systems.

 

[MDM]

Thanks. I found a Ranger site and found a fix that bypasses the vacuum system. It to me 15 minutes and she is working now.

 

[wushaw]

I guess Ford changed the hub system from 98 - 2000 since I just changed out a hub (sealed bearings shot) for my neighbor and there is not a locking hub of any kind, just a splined axle shaft for the rotor hub.

Glad ya got it working