Ok, so I just bought a 1999 expedition XLT. 4.6 l, A4WD. After fixing numerous lighting and electrical issues and changing plugs, she's actually running real nice. However, I've noticed a fairly pronounced ticking or clicking noise as I'm driving which I believe to be coming from tranny area. Almost sounds like the noise an automatic tranny makes if you put it in park before it stops rolling. But this sound is continuous, and seems to start once tranny shifts out of 1st gear. I've tried shifting into neutral, downshifting, and shifted it into and out of 4hi to see if it makes a difference. It doesn't. Oh, and also noticed that truck wants to roll a few inches when in park before it stops. Not sure if these are related issues or not. Any help as to where to even begin looking would be greatly appreciated. I've read about similar issues and it ended up being timing chain cassettes but wouldn't the noise occur while in any gear or even park for that matter since that is an engine only component?

 

Is your gear shifter loose? also how do you know its not your rear end making the noise?

 

Gear shifter seems to be tight. I guess I'm not 100% sure it's not coming from rear, just really seems to be being broadcast right from the middle of the dash, on the floor. Although by far not my first 4x4, this is my first A4WD. Is it possible that the shift motor is trying to constantly engage the 4WD? Is there a way to check/adjust this?

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By the way, thx for jumping on this one so quickly. Obviously I'd like to diagnose and repair before a catastrophic failure and not after!! Much appreciated.

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The rear exhaust manifold to block bolts are well known for breaking. The resulting exhaust leak is a ticking noise that you'd swear was metallic in nature. I'd start by listening at the front wheel wells to see if you can hear the ticking noise from there when idling.

 

if it is the AWD system you could disable by pulling s fuse I think? or is it by the Brown wire mod?

 

I did take your advice and check the bolts. All good. The darn thing quit making the noise all day, then the last 10 miles or so home, it started again. I'm fixing a hole in one tire right now, then I'll be checking more into this noise. I'll keep you posted as to what I find.

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So it turns out, the u-joint on the front wheel driveshaft, going into the tcase is completely destroyed. I've stopped my investigation there, until tomorrow night after work, when I pickup a new one and reinstall. For the time being, I've removed the culprit, and pulled the fuse for the 4x4 shift motor and clutch. I will repost the results when I get them. In the meantime, thx for the great advice guys and stay safe out there!!

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Alright, sorry it took a couple days, I was rather busy at work and missed the parts stores for a bit. Finally got the u joint, worked on it last night/today, and voila!!! Problem solved. Truck rides nice and quiet, and 4x4 works great. Thx again for all the great advice, and I'm sure there will be cause for future communications. Little lesson thru all this, always assume that noone has as stringent of a maintenance attitude as yourself, and inspect used vehicles very closely. I've found some rather ridiculous wiring, half hearted repair efforts, and evidence of plain and simple neglect.

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