During the brutal storm last month, I went to work and was ... hard ... on the car when I got stuck. I was able to get out, but I have a weird rattle that comes and goes during idle and is consistent as rpm/boost goes up. Like I can be accelerating in 2nd/3500rpm/vacuum and in 4th/2000rpm/5psi and it will make the same noise. I finally was able to catch it this afternoon after I changed the timing chain tensioner, as that is where the sound was coming from, but that only cured a minor rattling. I'm not sure if the car is down on power because I haven't gone WOT since this came about. I had high hopes for the t.c.t. fixing this.

The sound stops at ~6 seconds, before going back to normal idling noise.
VID_20130305_143229_zpsd5cd23ff.mp4 Video by blackyk | Photobucket

 

sub'd, got similar rattle in my LS

 

Bump ...

 

Can't hear much, but if it comes from underneath the car and it's constant, it could be the heat shield?

 

Ouch, it sounds like you may have stretched your chain, I was going to say supercharger coupler but that isn't the sound a coupler makes. Did you check the exhaust manifold for any leaks? When mine was leaking it was unbelievably noisy.

 

I tried putting a rag into the exhaust and it just shot right out, I could barely even hold it in the tail pipe by hand, leading me to believe there isn't an exhaust leak, as much as I'd love to have one as those are easy to fix, comparatively. I don't think the heat shield is the culprit because the sound changes its pitch with the amount of power produced, like lower rpm 5psi, higher rpm 5 in vacuum.

 

Bump for some more info ... Copied/cleaned up from a Facebook thread


The elusive rattling I have somewhere between the engine and cat. I thought I had broken something in the time chain area so I removed the valve cover only to find everything looking perfect. The TC has lots of tension, I poked at it with a kids plastic paint brush handle and it is very taught. So I put it all back together and I hear the rattle as I test fire to make sure I didn't mess anything else up. I see the morning start up smoke come out of the tail pipe so I begin to look through the exhaust for leaks along the gaskets and nothing. It sounded like a heat shield maybe but they all seem pretty solid and don't look like they are touching any metal. This is frustrating to say the least ...
Jeremy: Stock exhaust on the car?

Marcus: Yup. Only thing I've had to change was the header O2 sensor. Could it need to be tightened down? I used a proper O2 socket with the anti-seize grease.

Andrew: Could be the cat. If the honeycomb inside deteriorates, it can rattle around inside the cat.

Marcus: Does it sound metallic? I will make a note that this sound happened after I was really hard on the car back during that massive storm. I was stuck between two 5 foot snow banks, which I almost made it through, but the engine did get very very hot in the process. Could that have burnt up the cat? The only CEL I have gotten is P0171, and that happens all the time. I'll add that the cat is the basic area where I'm hearing the sound coming from too. I'm looking at Rockauto for 250 + shipping for just the DP/cat and 430 for ZZP's Mid Length Header + DP/cat. I don't want to order parts to just throw at the car either. And furthermore! ... The sound that the engine would make wasn't RPM based, but power based. Just cruising in town it would be completely silent, but if I were in 2nd gear/3500 rpm in vacuum speeding up, you'd hear it JUST AS MUCH as 4th gear/2000 rpm @5psi to produce the same amount of power/acceleration.

So my question to you all is ... could my problem be a blown out cat that has a chunk clanging around in the cat?

 

i had the insides of a cat break free in my saturn once, rattled like crazy until somehow it jammed itself in there such a way it was blocking one of the holes... so i had like no power until i replaced it

 

You got the cat hot and then the ice cold snow must've hit it and ruined it. I bet thats what happened

 

could be your TOB i had simular rattle a while back ....

 

Jt, I don't think the throw out is my culprit. The sound gets louder as it gets closer to boost, around 10 in/hg in vacuum. I'm trying the SC coupler first, then I'll take the exhaust off, which I'm not looking forward to since all the bolts from the DP/header gasket down are all rust. Chris has a similar idea as to what I was thinking of as well, just don't want to dump big bucks first, if the fix is cheaper. If the cat is blown, time for mid length header and DP from ZZP

 

my blower needs a coupler and it sounds NOTHING like that. i have a feeling youll be wasting money changing that part out trying to run down the problem. broken lifter maybe?

 

^^ Darn I saw a vid on youtube linked from somewhere on here and his coupler was gone and it sounded exactly like mine so I jumped on it. I took the valve cover off and there were no obvious signs of foul play under there.

 

It's the catalytic converter. But hey what do I know...

 

broken chain guide? Why don't u use a broom stick to track doen where the sound vibrations come from?

 

Chain guides looked good when I took the valve cover off.

 

Question guys my LSJ I just bought rattles when I accelerate a little more than half throttle or more and it sounds like I'm running low octane but I've got 91 in it any idea what it could be? Maybe tensioner? It has 104000 miles and idk if chain has ever be replaced