ESOF - 4x4 not engaging

getstuk · Feb 14, 2015

When the hubs are in auto, 4x4 does not engage. I thought it would be a vacuum problem after research on this forum but my defroster does NOT kick on when I put it into 4x4 high (just went out and tested multiple times). I'm thinking about going to Autozone and getting a vacuum pump tool to apply vacuum manually, but I feel like I might be wasting my time if the problem does not appear to be a vacuum leak. Edit: Just read about a $40 kit to redo your hubs, if it's not a vacuum problem...

"Before giving up on the hubs, buy the $40 kit from Ford and take the hubs off and clean them up. Some fresh lube and new O rings and you should be fine for a while, unless you have actual vacuum line problems. Nice to keep the ESOF if you can. My hubs were almost impossible to turn until I cleaned them up, now they are fine (for another winter)."

It sounds like it may be the solenoid or the vacuum pump itself...now that I think of it, that tool will help as it will show the pulse on the PSI gauge if it's giving me a pulse or not.

Any recommendations? Going to call around to see if I can rent this tool somewhere...

getstuk · Feb 14, 2015

dammit, nobody rents a vacuum pump with gauge anymore, looks like I'm buying one. Just curious, wouldn't the defroster still kick on to indicate a vacuum leak even if it's at the hub or a leak anywhere else in the system?

ckrueg · Feb 15, 2015

Iirc, the 08 and up trucks don't use vacuum for the air vents. I think they use electric actuators. My hubs are kinda hit or miss so I'm looking to test them for leaks soon as well

DWhite · Feb 15, 2015

My ESOF stopped working one day. You could turn the switch and the 4x4 light would lite up on the dash but it never would go into 4x4. I checked everywhere for vacuum leaks and nothing.

It turned out it was the solenoid on the passenger side of the fan shroud, changed that and it fixed my problem. Some techs at the local Ford told me it is pretty common to go out with age. My 04 6.0 had the same problem and was the same solenoid.

You want to make sure you check everything since the solenoid is $80-90 bucks and I wouldn't want to buy one to just be throwing parts at it. But it is a suggestion and another possible problem for you.

getstuk · Feb 16, 2015

Thanks ckrueg, I'll keep that in mind, first time I've read that.

DWhite, I bought a vacuum tester / brake bleeder to test this out, I don't think it's going to work right because it can only test negative pressure (vacuum) and not positive. Got the truck on jackstands in the garage now. What is this tool I'm looking for called? It should show negative and positive pressure...

f350guy · Feb 16, 2015

DWhite said:
My ESOF stopped working one day. You could turn the switch and the 4x4 light would lite up on the dash but it never would go into 4x4. I checked everywhere for vacuum leaks and nothing.

It turned out it was the solenoid on the passenger side of the fan shroud, changed that and it fixed my problem. Some techs at the local Ford told me it is pretty common to go out with age. My 04 6.0 had the same problem and was the same solenoid.

You want to make sure you check everything since the solenoid is $80-90 bucks and I wouldn't want to buy one to just be throwing parts at it. But it is a suggestion and another possible problem for you.

Same problem I had on my '09. New 'noid cured my ails.

drunk on diesel · Feb 16, 2015

x1000000 on the switching solenoid

Every ESOF truck I've owned has needed a new solenoid at some point during my ownership. Most common cause of your issue IMO

swinky · Feb 16, 2015

I just had to change a relay on my 03.

getstuk · Feb 16, 2015

Alright, I think it might be my vacuum pump? Here is a video of the noise it's making. I am having a tough time using this vacuum tool to tell if the pump is operating correctly since it doesn't gauge positive pressure. I'm going to try to feel for the pulse by hand...really need another person around to test though...

When I turn on the truck the vacuum pump engages for at least a minute, quite loud as you can see. And then it engages again when I engage 4wd, and the pump continues to run for a while. Any ideas on testing this? I can't seem to disconnect the hoses from the pump, I'm worried they're not designed to be disconnected there? Anyone with a diagram?

Video link

edit: I just saw the 3 replies posted, so the solenoid on the passenger side huh? I can replace that and then return it if it doesn't work (if they allow me to). But it's still strange the pump is behaving the way it is in the video, still think it's the solenoid?

DWhite · Feb 16, 2015

Judging from your video your pump is either going out or you have a vacuum leak. The only time mine has ever ran that long is when it had a leak.

DWhite · Feb 16, 2015

There is a few vacuum lines right in front of the degas bottle for coolant pull the hose off that is closest to the coolant tank and plug that rubber elbow with your pump or something and turn the truck on and see if your pump creates vacuum.

f350guy · Feb 16, 2015

Typically pumps run continually when there is a vacuum leak or filling a vacuum reservoir, I have some old Euro cars with a very similar pump. The white tit is open to the atmosphere, which is normal, as the pump must be able to discharge the air is is pulling out of the vacuum system. Think of your vacuum cleaner.

Before making yourself nuts, just go over all the vacuum lines by hand to see if there is a break anywhere. From what I remember Ford uses rubber hoses and plastic connectors. If you find it, cool. Mend it how you see fit and motor on... I would go with at least silicone hose and brass fittings where you can do so.

If all looks fine, I would pull a vacuum at each hub with the tool and see if they lock and hold the vacuum. If not, there is your problem.

If the hubs pass, work your way in reverse from them to the solenoid. From what I recall dicking with mine, the pump held vacuum at the solenoid but it was not switching which is why I had open hubs in 4hi/low.

Your solenoid could easily be fine. I do not have my junk one handy but I cannot be more than a few wires. So you can check the integrity of that with the vacuum tool and jump the solenoid to see if vacuum drops once the solenoid opens.

This is easier than you are thinking it is to solve. Just think if your house vacuum cleaner.

2mcclr · Feb 16, 2015

I'm currently having the same problem, except I've already replaced my solenoid. I put a new solenoid on last week and it seemed to fix the problem. Well, tonight after 9 inches of snow I tried to put it in 4wd and the hubs wouldn't lock in automatically. When I lock them in manually, the 4wd works perfectly.

getstuk · Feb 20, 2015

DWhite said:
There is a few vacuum lines right in front of the degas bottle for coolant pull the hose off that is closest to the coolant tank and plug that rubber elbow with your pump or something and turn the truck on and see if your pump creates vacuum.

DWhite, dammit...is this the vacuum line you were referring to, because I broke it trying to separate that elbow. It started hissing like crazy so I'd say it was holding vacuum. I'm going to try and repair it...

getstuk · Feb 20, 2015

Here is an updated video, found on which line the leak is happening -> Video.

Will continue to check the vacuum lines from this point back to the hubs...I returned that tool thinking it was going to be no use but now wish I would have kept it. Might be able to use it to test if there are any leaks in this line.

getstuk · Feb 20, 2015

Ok found the problem! Found a very simple way to test your vacuum lines and your solenoid, all at once and in just a couple minutes!

Assuming your vacuum pump is working (you'll hear it turn on as soon as you disconnect a "live" vacuum line), simply disconnect the vacuum line that comes directly from the pump and goes INTO your solenoid, and plug the vacuum pump line directly into the upstream vacuum line that's headed to your hubs. Check my video for how to do this in detail. This will completely bypass the electronics of the 4wd system and apply direct vacuum to your hubs. If you have no leaks in the vacuum lines that go out to your hubs from the solenoid, then the vacuum pump should shut off in under 45 seconds. If the vacuum hub continues to run for over a minute, you have a vacuum leak in your lines, but test whether your hubs are engaged by jacking up the front tires and spinning one tire with 4hi engaged. Your passenger tire and driver side tires should both spin together now (but in opposite directions if you have an open diff). If your hubs are not locked, and each tire spins independently of each other, then your hubs are unlocked and you have a vacuum leak or your vacuum pump is not functioning (this should be very obvious if it's not, test the vacuum with your finger over an active line, it should suck air).

My problem is the solenoid, thanks guys for your help. I'll update this thread when I've replaced it...looking for the part online now.

<uploading video now>