Hey guys....
I just purchased a 2000 Excursion and I need some help with some questions/issues i'm having. The first issue I'm having is that the driver's side hub isn't unlocking when in auto and 2wd. I have done quite a bit of reading on the forums in the past few days and I want to check out the vacuum line situation first. I did notice a vacuum line on the driver's side behind the tire all mangled up. Here is a pic:

It was just dangling down and I placed it on the knuckle for the photo. The one on the passenger side is the same way. Is this the vacuum line that locks and unlocks the hubs? Also...where exactly is it supposed to connect to....that little fitting on the knuckle right next to it in the photo? If it is not the line that locks and unlocks the hubs...what is it's function?

Next.....the round seal looking ring in this photo that i'm pointing to....what is it and is it supposed to be stationary all the time? The reason I ask is that with the wheels straight I can touch it and it will move around slightly in a circular motion.


I'm also trying to confirm which gear ration this Excursion has. According to the VIN decoder.....it has the 3.73 gears. However......when I'm cruising 65...the rpms are right at 2200. I've looked on the door tag and there is not code under "axle" on it. I checked the tag on the differential and it had the following:
3 PM 421 D
L30 10 5 9H 18
I checked the page with the Ford axle ID on it and I saw that there was an S421-c and an S421-F that applied to an Excursion but I saw no 421-D. Can anyone decode the tag and confirm the gear ration? Based on the rpms at 65....I was almost sure it has the 4.30 gears....until the VIN decoder said it had the 3.73 gears. Any help or information anyone has is greatly appreciated. I'm sure I'll have some more issues/questions here in the near future.

Thanks guys,

Jim

 

Welcome to the best online forum for Ford trucks!
Yes those vacuum lines should go onto the nipples on the knuckles, they are the ones that lock and unlock the auto hubs (if they still work).
The black seal that moves free around the axle is just a dust seal to keep too much junk from getting into the axle tubes, the actual axle seals are deeper inside the tubes. Mine and a lot of others here have our seals just like yours or worse with no ill effects.
I'm sure some else will chime in with rear gear info for you shortly.
More pics of the new EX! We love pictures!

 

I had a vacuum line that looked like that from the previous owner. Make sure to remove the fitting with the nipple and make sure it is clear ( not plugged up ). The vacuum won't work the hubs too well if the fitting is plugged.

Good Luck!

 

Thanks for the reply and the welcome. I'll get some pics up soon. Awesome. I'll head to Advance Auto Parts tomorrow to get some vacuum line to make that connection again on both sides. The funny thing is that in Auto and 2wd the passenger side hub is unlocked. Currently I have the hubs on lock so that one isn't locked and the other isn't. I did read that vacuum issues can cause funny things with the AC. I have also noticed that the AC will blow back and forth from the vents and the defrost slots. It'll blow from the vents for a while and then from then defrost....then back to the vents and so forth. Could these mangled vacuum lines be causing that? If the new vacuum lines don't unlock the driver's side hub....what would be my next course of action to get it unlocked?

Thanks again!

Jim

 

Auto hubs can get gummed up over time, here is a good step-by-step service guide. Welcome to guzzle's 4x4 Autolock Hub Lubrication Maintenance Web Page Some folks have had good luck just pulling them apart, cleaning and relubing without the new parts Guzzle used.
Broken vacuum lines will cause issues with the A/C and defrost, the duct doors that control the air flow are vacuum operated so the leaks can cause the doors to default to the defrost position.
Do both hubs move freely from Auto to Lock? When in Lock can you reach behind the wheel and turn the knuckle U-joint? (in Lock the U-joint should not turn by hand, in Auto yes.)

 

Once you get your vacuum lines straightened out, there's a trick that worked for me to unlock a stubborn hub.

Put both hubs in auto, then select 4WD LOW (there's a procedure for that), then drive the car for just a few hundred feet, down the street and back, then put the car back into 2WD. That can unstick a stuck hub. Of course it might do it again later but this worked for me when one of my hubs was stuck.

 

Both hubs will indeed move freely from auto to lock. When in auto....the passenger side u-joint will spin by hand but not the drivers side. After getting new vacuum lines on I'll see if that solves the problem. If not....I'll look at the solutions y'all mentioned. I'm assuming driving on the street in a straight line in 4 low for a couple hundred feet won't hurt anything?

Jim

 

I wasn't talking about the hub selector itself, I was talking about the hub not unlocking no matter where the selector is. Just to be clear.

What you're describing it exactly what I had (the drivers side not unlocking) and I have good vacuum lines.

No, driving on the road for a couple hundred feet in low won't hurt anything.

 

Another option with the hubs is to replace the stock ones with aftermarket hubs (Warn Premium, or MileMarker are the most popular). Just make sure to cap the vacuum lines that feed the hubs or you will continue to have AC/defroster issues.

 

You sure that Axle tag doesn't say S421C instead of the D? If so it's this one
<table id="table2" border="1" cellpadding="2" cellspacing="0" width="98%"><tbody><tr><td bgcolor="#FAE9D1">S421-C</td> <td> Excursion '00
Ford F250SD, F350SD Pickup ‘99-01</td> <td align="center"> 4.30</td> <td align="center"> 10.50</td> <td align="center"> L</td> <td align="center"> -</td> <td align="center"> full-float</td></tr></tbody></table>
Could be stock but since the VIN is decoding 3.73 and your rpm doesn't seem to match that, then it could also be a donor axle put in the truck from a F250/350.

What's the front axle code?

Check and post before you do anything else with those hubs. It's not unheard of for someone to change the rear and not change the front, so you want to know that before you go locking in the hubs and engaging 4x4. Maybe the PO disabled/buggered up those vacuum hoses on purpose? Pretty rare but is a possibility that occurred to me based on what you've said.

 

The guy I bought it from did engage the 4wd and drove it a short distance with it engaged. If the axles had different ratios....would it even drive? I'll check the front differential first thing in the morning and re-check the tag on the rear differential as well.

Jim

 

He might have put it in 4WD but since you said the hubs were not locking he didn't have the front wheels engaged, and I know the real issue with different gear ratios is the tires turning at different speeds. I'm no expert so I am not 100% sure if you have different ratios and engage 4wd with the hubs unlocked if you would be able to feel it or not. Paging those with axle smarts....

 

Actually.....the main issue I'm having with the hubs is that they are not unlocking in auto/2wd. When I purchased it, the hubs were on manual lock. When I switched them to auto, the driver's side would not unlock. As for an update.....I did replace the vacuum lines and it didn't really do anything to get them, to unlock. I did try switching into 4low, driving for a couple hundred feet and then switching back to 2wd but they are still locked. I did notice that now....the passenger side isn't unlocking in auto like it did before. I'm assuming I drove far enough for them to unlock after switching back to 2wd. I guess I'll look at pulling the hubs to see if they are just gummed up. At idle...what kind of vacuum should the lines attached to the knuckle be pulling?

I do think I confirmed the gears in the Excursion though. I crawled up under the front and never found a tag on the front differential but I did see one of the white stickers with the yellow stripe on it that had some info and it did have 4.30 on it. I'm guessing the VIN decoder was just incorrect (especially since there was no stamp under axle on the door tag). I got the oil changed and next up is the transmission fluid. Are the filter sets from Advance Auto Parts ok to use or should I plan on getting one from the dealership. The reason I ask is that I have an 06 Jeep Liberty diesel that everyone swears by the dealership transmission filter kits vs the autoparts store. Is this the rubber plug I need to pull to access the bolt in the torque converter to drain it or do I need to remove something else to access it?

Is Mercon V the fluid of choice?

Thanks again guys, Jim