-Little history:

2003 Excursion. About 129k miles. V10. 4wd. The electronic 4wd has been changed over (the previous owner put the regular Warn hubs in front,) so whenever I needed to use 4wd before, I would have to lock the front hubs and turn the electronic selector switch to 4wd... (I think?)

Well... I needed 4wd yesterday in Northern Wisconsin. Ran in 2wd for about 2 hours, and pulled off for gas. Hubs had been 'locked' but I did not have the electronic 4wd switch moved to 4wd high. Before leaving the gas station, I moved the switch to 4 high. Immediately the truck felt like it was wanting to pull all over the road. Made it scary as **** to go from snow to pavement to snow... the Ex would go all over the place (did not do this in 2wd.)

Figured maybe fluid was cold or something, so I took it slowly getting back in the interstate. Got about a mile or so down the road and I could hear a distinct whining noise. Slowed down to about 55. Whining lessened. Then the whining started coming in louder and I could almost 'feel' it in the gas pedal and steering wheel. Knew immediately that something was ****ed up. Pulled off to the side of the road (thinking it was as simple as taking it out of 4high.) I turned the electronic switch to 2wd, unlocked the hubs, and tried to drive forward. Same nasty 'grind' and 'whine.' Stopped again. Double checked both hubs to make sure that they were not locked. Put the truck in reverse and backed up about 15 feet... No whine or grind. Put the truck back in Drive, and the noise was no longer there. Proceeded to drive all the way back to Central IL in 2wd without an issue.

So I made it home and am now trying to figure out what the frick was causing this issue.

Honestly not familiar with 4wd systems. Used to AWD systems in newer vehicles where the stuff just works.


1. What do you think was causing this noise/grinding?
2. Did I do damage to anything by leaving the hubs 'locked' and not turning the electronic selector to 4high?
3. Is 4wd supposed to be almost dangerous (by whipping back and forth across the road) when going from a slippery surface to a non-slippery surface?
4. Suggestions on how I start to diagnose this?

Educate me please. I'm afraid this will be an expensive lesson.

 

Can someone verify?

The locking hubs do nothing more than lock right at the hubs?

If for some reason my 4wd high was not releasing, I would still be turning the front diff... but just not the spindles?

 

The hub's will lock everything in the front drive line up. If your hubs are Locked, they are turning the axle shaft's, the differential, the front drive shaft, and the transfer case. The transfer case just isn't sending power to the front end.

FWD shouldn't cause a drastic change in handling. (darting all over) With that said, it isn't uncommon for the vehicle to move a little when going from snow to pavemant to snow......etc. Check Your U joint's, check all the bearing's, and check your hub's.

Did you buy this used? Could it have a different Ring and Pinion in the front? Does it maybe have a limited slip in the front? (This sound's like a dumb question, as ford never put LS in the front.......But I had a 95 F-150 that darted all over, and to my surprise there was a clutch pack in the diff.........I didn't install, and the original purchaser, a 70yr old before me didn't install).

You are correct that if you put the hub's to Free, you are sending power all the way, just the axles aren't sending power through the hub's to the wheel.

 

I picked up a small rock between my wheel and front brake on my Boxster last week that made a very sick sounding metallic grind. I was expecting all sorts of expensive repair bills until I finally found it and pulled it out. Hopefully you will have something just as simple.

 

Maybe the PO re-geared the rear end and not the front. Happened to my friend on his f150.

 

Just an update.

Have been beyond busy and have yet to do anything with this.

Today I had 3 minutes so I drove it around the block.

Makes no noise or howling with the front hubs locked and electrical switch to 4wd. Only makes the noise when I flip the switch to 4wd... regardless of wether or not the hubs are locked.

 

Make sure the hubs are unlocking all the way by attempting to spin the axleshafts or front driveshaft. A partially locked or partially unlocked hub will GRIND.

As for the darting, I have heard of similar issues from stiff or failed u-joints on the front axleshafts. This would only happen with hubs locked though - basically hard steering and a lack of return-to-center.

Verify front diff is full of fluid as well.

I guess REALLY bad unit bearings could be a problem as well or even ball joints - although these are a bit of a stretch. Jack a front tire about 1" off the ground and use a crowbar to try and lift the tire while someone looks at BJ's and unit bearing.

Keep us posted!

 

Thanks!

One key thing to correct from my post above...

Makes no noise or howling with the front hubs locked and electrical switch to 2wd. Only makes the noise when I flip the switch to 4wd... regardless of wether or not the hubs are locked.