03 AWD Clunking sound from back when starting acceleration.

[brandontw]

Just picked up this car, and have been doing a lot of research.

It appears the AWD can be problematic if it runs low on fluid, but the reported symptoms of this don't seem to match my sound.

I first noticed that starting and stopping at stoplights there was a slight knock/rattle/thunk in the back somewhere. From the sound of it i figured there was just something loose in the back, either in the spare tire area, or in one of the storage pods. I was almost positive it was the jack or something shifting, so I got back there and stuffed towels around all loose parts, and even in the body panels behind the side cubby holes.

Needless to say, I don't think its anything loose inside anymore, unless there is something way behind the panels or something. So... any ideas for other possible causes? I'm going to try to eyeball the rear diff for leaks after work today. Could that cause this sort of sound? I don't think I hear any notable whining, or any odd sound at any speed, just the clunk, mostly right when you first let off the brake and start to accelerate.

The transmission seems tip-top to me, shifts excellent. Brakes too, but i'm no mechanic.

[Salsa Guy]

I read you are going to check the seal for seeping which is good, but also check the rear diff and transfer case fluids, the drive shaft U-joints and CV joint/boots.

[brandontw]

Ill give it a shot... im not really sure what im looking for when it comes to driveshaft/cv joints.

[Salsa Guy]

First make sure you have the car on jack stands. Check for slop on the drive axle U-Joints. On the CV joint check the boots and any excessive play.

[brandontw]

I've got the car up on stands right now changing the diff fluid. Didnt look like it was leaking one bit.

The drive shaft feels stable and unmovable.

This my first time even touching CV arms/joints, but I'm suspicious that they might be the culprits. If I grab the arm and wiggle it, it has movement (forward and back along its length) but no movement sideways or around. They both do it, the right seems to make a bit more noise than the left. How are CV joints supposed to feel? Are they supposed to move and make slight noise when you move them?

[Salsa Guy]

They should have movement along the length but not any real noise. if you try and rotate them they should be solid and the wheel will move with them. When I heard you say that CV was the first thing I thought of, then U-joints. can you tell if the noise is coming from one side or the other. The cv is about $75 and install about $125, then you'll need an alignment. I'd suggest do both sides.

[brandontw]

SOLVED!

Thanks for all your help man. I finished up the diff fluid change and set her back down, and drove around the neighborhood starting and stopping like a creep. The sound was still there and it sounded interior, like there was something kicking around in the spare tire well.

So I took the spare tire and tray completely out, that's when I discovered there was another long skinny compartment with lid right behind the seats. There was some mystery metal tube loose in there. I honestly don't even know what it is, if it goes with the car I don't know what its for.

TLDR: Mystery tube in secret floor compartment.

[Salsa Guy]

AWESOME!!! That saved you hundreds! Just keep an eye on those rear diff seals. The only other tip I could give you is if your front CV joints start going bad you'll get a vibration during moderate/heavy acceleration. You may or may not hear a clunking noise during turns. I thought at first was thinking the transmission or engine had issues but it turned out it was the CV joints.

Also those front CV joints are a pain to get because of the AWD. The passenger side needs special attention because you need to partially drain the Transfer case and the Transmission.

[brandontw]

Sweet. Thanks a lot man. I guess my CV joints are good enough for now, but ill keep an eye/ear on em. And ill keep checking for leaks on that diff too. It looks like it hadn't leaked a drop in its life, or may have had new seals, and i put new royal purple synthetic in it, so hopefully it stays legit.

[Salsa Guy]

Royal Purple is good stuff. I run AMSoil in the Transfer case, Rear Diff (Server Gear) and Auto Transmission (Universal)

[brandontw]

Yeah, I would have preferred amsoil from the recommendations on here, but i couldn't find any locally, and I felt like doing it right away. Royal purple was the best i could find.