I need some help. I have an 2000 Excursion 7.3 Limited 4WD. As most of you know it snowed like crazy this last week here in Las Vegas. When I flipped the selector switch from 2H to 4H the light on the dash did not come on (both 4wd and low range lights come on a start up, like normal). I see from the forums that there is a lot of vacuum leak issues with the ESOF. I will dig into this and see if that is what I have. My question is when I lock the hubs in manually, does this supply power to the front wheels??? Anyone that can explain exactly what happens when hubs are manually locked?
Thanks,
Clint.

 

The hubs only lock the tires to the axles. In either auto or manual, it slides a piece in that grabs the hub (what the wheels are bolted to, and holds the brake disc) and grabs the splines on the end of the axle. They do not engage the transfer case (the mini-transmission that directs power to rear driveshaft all the time, and to the front driveshaft during 4wd.)

On the ESOF setup, there is a little electric motor that moves the transfer case into 2wd, 4hi and 4lo. There is a relay I've heard that malfunctions as well, so it' not just a vacuum leak that can be the trouble. Try locking in the hubs and turning the switch, the hubs being locked, if the transfer case engages, your in 4wd. If the case fails to engage, then you have a problem on the transfer case side.

 

10-4. Any idea which relay is the culprit?

 

It will probably be labeled as 4wd or transfer case and be in the underhood relay box. You can look up your owners manual at http://www.motorcraftservice.com if you need one. Krewrat will be around and I think he'll know which it is.

 

I appreciate it.

 

Does anyone happen to know what size of replacement hose I need to buy for the vacuum hose?

 

It's small. I recall wanting 3an braided hose to dress mine up, so it's in the 3/16" ball park.

 

I just pulled one of the hub and took it into a parts store-5 feet for 7 bucks.I forget the size but Reax is right-it's a small diameter hose.If you want to really upgrade the line there is a sponsor here-Dieselsite that has some nice braided lines.

 

Lots of good info here:

https://www.ford-trucks.com/forums/8...ot-engage.html

I'm going to take an educated guess... The problem is less likely to be the vaccuum hose... more likely to be the seals inside the hub assembly (not the 4X4 lock hub, but the wheel hub assembly).

Heres a link with more info on the hub assembly seals:

Welcome to guzzle's 4x4 Needle Bearing Maintenance Web Page

For your case... I hope it's the former and not the latter!!

Good Luck!!

 

So, you're saying the 4x4 light doesnt come on when you shift it into 4x4? Then, its probably the electric motor that shifts the case, not the hubs. You can see if its the hubs by turning them to lock and seeing if the 4x4 works then. Also, be careful with the auto hubs, the face is made of a porous stone that breaks easily.

 

You’re absolutely right; I broke apart the hubs trying to free them. I now have Mile Marker Manual Hubs #MMK-449SS. If I need 4WD I lock them, when I don't I unlock them.

 

I have problems with every ESOF Ford I've owned. At 35.5K miles had the electric motor on the transfer case fail on a 99 F150.

Had problems with the F250 so put Warn hubs on it and they work great. one hub fell off and the other just stopped working. The F350 had Warn premiums on it when I bought it. The only draw back with non factory hubs is you have to lock them to engage 4x4. I like the Warn Premiums better than the standard one. The Premium is easier to turn and you don't have to turn as far as the standard one.

Now the Excursion is not going into 4x4 with the factory hubs locked in. At 194K miles suspect the locking hubs are shot.

 

On one of the other posts that I researched I read that if you have the heater blowing on the floor, turn the 4-HI on, then if there is a vacuum issue the heater blower will default to the defrost mode. When I did this there was no default to defrost. Does this method work in identifying vacuum issues?

 

I think it only works on the diesel, because of the turbo charger there is no steady manifold vacuum to run diverters off of. So Ford plumbed the ESOF and heater together.

 

Sounds like it might not be the vacuum then. I guess the next thing to do would be checking the electric motor that pushes the transfer case into gear. I have looked at the fuses and all seem to be good. Any ideas are greatly appreciated.