Ford Power Stroke Nation banner

1 - 20 of 23 Posts

·
Registered
Joined
·
2 Posts
Discussion Starter #1
First of all I am new to the site and have already learned alot from all of you. Thanks.
I am not sure if this is where I need to post this but I have a problem with my 4wd. I purchased the truck in November and hadnt' had a need for the 4x4 until recently. I got in a wet spot and began spinning. My hubs were in auto and I tried to engauge them but the 4x4 would not kick in. After some back and forths I got out. I turned the hubs to locked and engauged them and the 4x4 did kick in. But then I tried it again the other day and neither way is working, auto or locked. What could be my issue? Really should have checked the 4x4 when I purchased it but I was buying from my best friend and he said he had no clue it was not working properly bc he never used it. Thanks in advance for the help.
 

·
Registered
Joined
·
160 Posts
Sounds like its a vacuum problem either the vacuum pump took a chit or your wheel lock hub vacuum solenoid is bad and not letting vacuum to the wheel hubs.Mine went bad on my truck same thing would not engage either.Ford is the only place that sells it my cost was $66 bucks list for $88.Do this test turn key to run don't start the truck turn your switch to 4x4 you should be able to hear the vacuum pump run it's on the passenger side in front off the evap case behind the vacuum reservoir.
 

·
Registered
Joined
·
160 Posts
Or the hubs are bad forgot to mention that what year is the truck.
 

·
Registered
Joined
·
90 Posts
Do a search on youtube. I tested my hubs by buying a small hand vacum pump from harbour freight. Jack up one side and hook vacum line to pump spin the tire and apply vacum. Hubs should engage, if not then its your hubs. If they do engage then you have a leak or no vacum from your pump
 

·
Registered
Joined
·
160 Posts
That's another good test to do a vacuum pump will tell you if your hubs are phucked if they won't hold vacuum.Or it will tell you if they lock then you will know if you have a vacuum problem.I just fixed my buddies raptor one side was trying to grab so it would make a grinding noise.The right side had no vacuum the f150s use vacuum to hold it in 2x4 till you turn the knob to release the vacuum.He had a broken vacuum line on his truck.Are trucks use vacuum to put it in 4x4 go figure lol.
 

·
Jackleg Mechanic
Joined
·
881 Posts
It sounds like you have two problems, if you manually lock the hubs vacuum is out of the picture. If 4x4 don't engage with manual lock you have an electrical issue. If the dash light doesn't come on when you flip the esof the shift motor is not activating, and has nothing to do with vacuum. If the light comes on when the esof is switched and your front wheels don't pull then you have a vacuum problem.

Check all the 4x4 related fuses. If all are good then test the two relays in front of the driver battery. Imo, You will need to get the indicator light working then figure out the vacuum problem.
If the 4x4 light cycles when you turn on the key the pcm is communicating with the shift motor and it is likely not the problem.
 

·
Intelligent Burro
Joined
·
450 Posts
Still not sure what year truck we are talking about.
On the older SD's, the vaccum also operates the heater vents. If it will only blow air out the defrost and will not change to "floor" or "vent". You definitely have a vaccum leak.
 

·
Registered
Joined
·
38 Posts
I have a stupid question that I need an answer to. I have a 2000 4x4 F350 and I can't tell if my 4x4 is engaging or not. I've turned the key and heard the vacuum pump working. my 4x4 light comes on but i still don't feel like I'm in 4x4. I've been stuck twice. I'm told I have to be in N with my foot on the brake. I've been told I need to roll forward to engage so if I'm stuck, switching the dash won't work b/c I can't roll into 4x4.

Is there a way to tell if I'm engaging other than finding a mud hole somewhere and flooring it?
 

·
Administrator
Joined
·
32,985 Posts
put it in park and grab the front driveshaft and see if it free spins

also reach inside both steering knuckles and try to spin the axles by the u joint


if your dash light comes on this tells u your transfer case has done what it is supposed to and a has been verified by a signal but the system can not check the hub lock so chances are your drive shaft wont spin but one or both axles might
 

·
Registered
Joined
·
38 Posts
And if 4 wheel drive is working, everything should be locked, correct? If it spins freely that means I have an issue in that area, correct?


Sent from AutoGuide.com App
 

·
Registered
Joined
·
38 Posts
In 4x the drive shaft locks but the u joints don't. The hubs don't turn when the vacuum pump runs. The hubs are original and very tough to turn manually. Is there a way to know if new hubs will fix the situation? Or could I have a vacuum leak?


Sent from AutoGuide.com App
 

·
Administrator
Joined
·
32,985 Posts
you put a vacuum guage on the system and see if it is applying the vacuum signal
and you can hook a vac pump to the hubs and see if you can get them to lock under vacuum
 

·
06 FX4,4" Rough Country
Joined
·
101 Posts
I have a stupid question that I need an answer to. I have a 2000 4x4 F350 and I can't tell if my 4x4 is engaging or not. I've turned the key and heard the vacuum pump working. my 4x4 light comes on but i still don't feel like I'm in 4x4. I've been stuck twice. I'm told I have to be in N with my foot on the brake. I've been told I need to roll forward to engage so if I'm stuck, switching the dash won't work b/c I can't roll into 4x4.

Is there a way to tell if I'm engaging other than finding a mud hole somewhere and flooring it?
another real quick way is put it in 4x4 on asphalt and turn the wheel all the way to one side and drive forward slowly. if 4x4 works, your inside tire will skip and churp bc its trying to rotate at a slower rotation pace than the outside wheel and cant bc its locked. it will be VERY obvious its in 4x4 no question about it. let me know how this turns out
 

·
Registered
Joined
·
38 Posts
I'm going to try the vacuum lines and if that is good I am going to clean and grease my hubs. I'm thinking my hubs are jammed up w dirt because I could barely engage them manually.


Sent from AutoGuide.com App
 

·
Registered
Joined
·
38 Posts
Ok. So I did some diagnosing of my problem.

After looking behind both front wheels, one didn't have a vacuum line and the other was rotted into two pieces.

I hooked the vacuum pump direct to the back of the hub housing and applied vacuum. Hub didn't rotate but at least it held vacuum on both sides.

I hooked the vacuum test pump up to the line going back toward the engine vacuum and it didn't hold a vacuum.
I don't know if that's because 4x4 wasn't engaged. I guess I should have tried that but I was sidetracked and lost time.

My question: does anyone know where I can find a diagram on how these vacuum lines run since I'm probably going to need to run all new lines? Also, what side tubing do I need? 7/16 or 3/4?

Thanks!


Sent from AutoGuide.com App
 
1 - 20 of 23 Posts
Top