2003 Expedition, 4x4, 5.4
I've had a slight binding / grinding noise fwhen turning from a stop for the past few months. I believe it is from the front. You feel it in the seat and steering wheel more than hear it. Been to the dealer once and they couldn't replicate it. I took it home and have narrowed down the scope of when it happens, and will be going back in on Tuesday. I'm 300 miles short of my 100k power train warranty, so it is time to fix it or pay later. Here is how it happens; Sharp left or right turns from a stop with load (either from heavy acceleration or a hill, or a combination of both). This only happens for the first 15 minutes or so of driving, after which it goes away. I have the LSD rear, and have changed the fluid (with modifier), and I have also changed the front diff fluid. Trans has always been serviced ahead of schedule and was done around 10k ago. Thoughts or suggestions?

 

Transfer case fluid?

 

Are you sure it's a metallic grinding? If not, it could just be that the front end is out of alignment. The fact that you're feeling it in the steering and mostly at hard left/right turn take-offs tends to point to this as the problem.

 

Haven't looked at the T-Case. Good place to check. It is more a bind than grind. Sort of like the binding you get when in 4wd on dry pavement, but no where near as "bound" as that is. It doesn't cause any bucking, just a little feel of something not rotating as cleanly as it should. The real rub is that it goes away when it's warmed up.

 

I had similar problem with old transfer case fluid. Was a snap to change and it went away instantly. It was kind of a shuddering too.

 

What fluid does it take? I'll pass an auto parts store before I'm able to crawl under - is it a drain and fill plug set up or a gasket job?

 

An 03 takes ATF in the transfer case.

I know you said you changed the rear diff fluid and added the friction modifier, but I'd still be suspect of that LSD rear with how many 03's and 04's had problems with it.

 

It is likely a drain and fill plug setup. Always remove the top or fill plug first so you can be sure you can refill the tc. Then remove the bottom drain. They usually take about 2 quarts to refill. A pump that screws onto the bottle for refilling (5 or 6 bucks) makes the job pretty easy.

 

broncoholic - I've been down the clutch pack route 3 times with this truck, once with my previous one. It just doesn't feel like it. That binding was clearly coming from the back, the current bind feels more like the front / middle of the car. I'll grab some ATF and try to get some time underneath in the next day or two. May not fix it, but it can't hurt. And it's cheap. And it's an excuse to hang out he garage and have a beer.

 

Have a beer for me, oh heck have a six pack

 

BTW does the 03's have a rack or steering box, not sure because I have not owned one newer than 01, but if its a steering box I would check the pitman arm and associated steering linkages.

 

Did the T Case tonight. Doesn't seem like it helped, but I'll give it fair shake in the morning. Mercon is spec'd, I used Mobil 1 which says it is a replacement for it. 10 minute job, turned into 30 when I knocked over a quart of fluid. Good thing I had an extra. Looks like the dealer will have their crack at it Tuesday.

 

Suck Mine was better immediately

 

Man spilled fluid makes a mess, space is tight when working underneath easy to knock over stuff

 

I was really hoping that at the end of the driveway it would be better.