2004 Expedition Issues - Ford Forums

bflblz · 10-06-2008, 14:19

I've got 2 issues that I'm trying to solve on my '04 Expy. Any help would be great!

1) Rear Diff leaking. The seal around the drive shaft contiues to fail. I've had a new drive shaft installed, the seal replaced and it's still leaking.

2) After I come to a stop and begin to drive away, I hear what sounds like a "thunk" coming out from under the front of the truck. I can feel it too. This only happens after a full stop and I'm going straight after the stop. If I make a turn after stopping ... the sound doesn't happen.

I'm really stumped on the first one. This has been an ongoing affair for awhile now.

**360ci** · 10-06-2008, 17:22

1. driveshaft may be out of balance causing the seal to fail.
2. u-joints! Another indication that you need new u-joints is if you get a 'thunk' sound or feel when you put the transmission into gear. U-joints are what connects the driveshaft to the axles. By the sounds of things your u-joints probably aren't badly worn yet.

**jwko** · 10-06-2008, 17:42

Quote:

Rear Diff leaking. The seal around the drive shaft contiues to fail. I've had a new drive shaft installed, the seal replaced and it's still leaking.

Pinion bearing slack/failure?

bflblz · 10-07-2008, 11:54

Thanks for the responses!

Just talked to my mechanic (a guy I really trust btw) ..

1) The Drive shaft had been balanced ... but one of the weights came off. He was really surprised to see this so the thinking is they re-balance and it should solve the issue with the rear leaking.

2) The "thunk" I'm hearing is the 4-wheel drive engaging and disengaging. He "poked" around and couldn't find a leak anywhere nor with the vacuum pump. Nothing from the computer shows an issue. But now after looking around they can't get the problem to re-produce. Is there something else they should be looking for?