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SOLVED - SEE POST #10


Hey everyone

It seems I've had a poor run of luck at the moment with my 02 TJ, and keep having issues coming up :(

In the past week or so, I've got a pretty bad metallic rattling sound at low RPM, only between 900-1400. However from 1500+ it purrs along fine.
It usually happens (and it sounds at its worst ) when the engine is cold, but also sometimes continues to happen once the engine is warm.

It only happens whens I accelerate in either drive or reverse (under load) and never happens when I rev the car in neutral.

I had the timing belt tensioner replaced a bit under a year ago, and it sounds similar, however startup is fine, and it only happens once put into gear and I start driving, and still happens when the engine is warm. So I don't think that is the issue?

Here's a video of it happening. Note that it sounds like it's happening when I turn the wheel, but it happens both when turning and when traveling straight ahead, and is only depended on when I press the accelerator.

https://www.youtube.com/watch?v=k1UZtbwJ-VI



I've got a second video coming shortly (still uploading to youtube) where I stuck my phone in the engine bay and recorded a 2 minute drive, and you can hear the rattle more clearly.

https://www.youtube.com/watch?v=nMj4fSAk-0Y
*Warning it is a little loud, so you may want to turn down the speakers a little*
Incase you were wondering, the camera was pointed at the washer reservoir bottle, and that's what can be seen moving about


TL;DR
- Engine rattle between 900-1400 rpm only
- Only happens under load
- Happens when cold and hot

- 2002 TJ tiptronic auto with 105,000kms



Any help in diagnosing what the problem is would be greatly appreciated. It sounds like crap and I want to get it sorted but don't know what's wrong!

Thanks in advance :D

sounds very tinny, like a loose baffle in the muffler or a loose exhaust mounting or a loose guard on the exhaust manifold.

Engine mounts shot and exhaust touching somewhere? Have a good look at all 4 rubbers for cracking or disintegration.

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If the power steering belt is not tight enough it makes a rattle at low revs. It may not be loose enough to slip, but can still cause this noise. Try tightening that first.

Noise is fairly extreme but sounds like under tensioned drive belts, in particular the large alternator belt. have had that on a couple of gen 3 . Pretty much happens as you describe only in gear under load at those RPMs . depending on how bad can go away once warm or if loose enough, hot and cold.

The other thing that gets mentioned which I've had not experienced is the y-pipe rattle (internal). I'd check the belt tension first, also watch out for a separating harmonic balancer , also had that too.

i would also look at the tensioner pully. mine sounded like this

Thanks for all the input guys! AMC is an awesome source of knowledge and experience.


Engine mounts shot and exhaust touching somewhere? Have a good look at all 4 rubbers for cracking or disintegration.
Thanks, I've checked all 4 mounts and they all seem normal with no eye-catching damage


sounds very tinny, like a loose baffle in the muffler or a loose exhaust mounting or a loose guard on the exhaust manifold.
I'll put the car up on axle stands and have a better look at the exhaust system tomorrow.


Noise is fairly extreme but sounds like under tensioned drive belts, in particular the large alternator belt. have had that on a couple of gen 3 . Pretty much happens as you describe only in gear under load at those RPMs . depending on how bad can go away once warm or if loose enough, hot and cold.
It sounds like it could be that, thanks. I'll check that tomorrow. How much play should it have? And how much is too much?


If the power steering belt is not tight enough it makes a rattle at low revs. It may not be loose enough to slip, but can still cause this noise. Try tightening that first.
How would I go about checking/tightening it? Or is it a job for the mechanic?


i would also look at the tensioner pully. mine sounded like this
I had the tensioner replaced about 10 months ago, and the pully bearing was replaced with the TB about 30,000ks ago. I wouldn't have thought they'd fail so quickly?

If the power steering belt is not tight enough it makes a rattle at low revs. It may not be loose enough to slip, but can still cause this noise. Try tightening that first.

I agree with Jimbo.
I had a rattle similar to the one in the video and once I replaced the accessory belts it went away. Now it's back I assume due to belt stretch.

It was not as loud as yours though

usually quite tight, generally not much movement by hand, but then I have muppet arms. 98 newtons is the same as 10kg weight.

Hopefully Someone a little more qualified mayexplain this better.

http://www.aussiemagna.com/forums/attachment.php?attachmentid=48213

Thanks for all the input guys, I've been able to find and fix the problem :)

I was able to track the noise down to the AC compressor, and when the noise was happening, it was vibrating like anything.
I thought it could be that either the compressor itself or the bearing was on it's way out, but the noise was neither intensified or diminished when the AC clutch was engaged or not.
The belt is in good nic, and had about the right level of tension on it (about 1cm of deflection), so I ruled that out as being a cause.

For those that haven't done much work on this area of the engine, the AC compressor is bolted onto a metal frame, which in turn is bolted onto the engine.
The bolts between the compressor and the frame was solid, but the frame to the engine was loose!

I took the belt off, and unbolted the compressor from the frame (NOT the pipes!)
http://i258.photobucket.com/albums/hh271/PMC_191/AMC/IMAG1010.jpg


There is supposed to be 4 bolts bolting the frame to the block, however when I got to mine, there was only 2, and they were loose at that!


The bolt in the top left was completely missing, and the bottom right bolt had been snapped/sheered off, leaving half of it still in there:
http://i258.photobucket.com/albums/hh271/PMC_191/AMC/IMAG1006.jpg

I went to the local wreckers and got the required bolts, and was able to put the 3rd missing one, and tighten the other two right up.
Here's the frame with 3 bolts in, unable to put the bottom left one in
http://i258.photobucket.com/albums/hh271/PMC_191/AMC/IMAG1009.jpg

I then put the compressor back on the frame, put on the belt and tension it back up, and put back the splash guards.


It's been a few days since I did all this, and have had no hint of rattle at all :D


It's something I will keep an eye on, since there is only 3/4 of the bolts holding it down, and re tighten them if the need arrises.
I have spoken to Mal, and he said he has some tools that could get the job done of removing the broken bolt from the block, so that's something that will be done next time I get the car booked in.

I'm still pretty surprised that the bolt was sheered off, since it is a reasonably thick bolt (1cm'ish in diameter), and it's not really in a place that I would think would be under lots of sheer force.

I believe that the RPM of around 1000 was just the right resonating frequency, so the vibration was at its worst. And not sure why it only happened under load and not in neutral, but hey it's gone :)

Good result and thanks for the detailed follow up, I'll be checking the tension on mine first chance I get!