Schantin

iTrader: (6)

My car started making a horrible metallic rattle/clatter a couple days ago. I am at a loss. Any help diagnosing this would be greatly appreciated. Video is included below:

Here's the rundown:
1. Noise is loudest at start-up. Seems to quiet a bit once the engine is warm.
2. Rattle frequency increases as RPM increases, till about 3K RPM.
3. Rattle is most prominent on the passenger side of the car. Loudest underneath. Not sure if that's the exhaust amplifying the sound, or if the noise is actually coming from the transmission.
4. Pulled the passenger valve cover. Springs/rockers looked fine.
5. Pulled spark plugs on passenger side. All show normal wear.
6. Drained/changed oil. No metal noted in oil.
7. noise started abruptly when I was driving to work. Had to drive the car home (about 35 miles). Car drove fine, even at 90mph on the German Autobahn. Power felt normal. The AFR was 14.6 at cruise and 12.4 WOT, so it seems normal.

http://youtu.be/6GPkm7OFlj0

[URL="http://www.youtube.com/watch?v=C6RXNv-3-rI"[/URL]

I'm shipping the car from Germany to the US on Monday. Hoping it doesn't die en-route to the port or in-transit.

Help appreciated (and needed). Thanks.

ang1dust

Take your belts off, run it for a couple seconds and see if its a pully. It doesnt sound internal to me. Im semi noob but i like to diagnose. Make sure you take the AC belt off also because my 250k camaro needed both AC idler and tensioner pullies.

JRENIGAR

iTrader: (37)

This^^^ Same thing happend to me. Noisy-er when first started but fine when running for a while. It was the a/c pullies...

Schantin

iTrader: (6)

Tried the car without the belts. No change. Appreciate the suggestion though.

A bit more info: When I did my cam swap 25K miles ago, the front cam bearing was worn with a small groove in it. Could a failed front cam bearing cause this noise? I'd expect it to resonate EVERYWHERE if it was that bearing. Again, this noise is concentrated on the passenger side of the car.

Additional $0.02 needed and appreciated. Thanks in advance.

z28clark

iTrader: (2)

I'd lean more towards a lifter, your oil pressure stays steady and is good?

Schantin

iTrader: (6)

Oil pressure is good. Thought of a lifter too. But... All the spark plugs show even wear and it's more a rattle than constant tap. Doesn't mean it's not a lifter. Will have to tear everything apart once I have the car stateside.

This is a total head-scratcher of a problem for me

z28clark

iTrader: (2)

It is a unique noise I'll give you that! Have you tried pulling a plug wire one at a time to see if it deadens the sound? Could help determine exactly which cylinder it is.

gMAG

iTrader: (1)

^^^^Good idea.

poltergeist 02

iTrader: (65)

maybe the starter is not disengaging?

lt1pwr1

iTrader: (1)

The fact that you say there is no metal in the oil is a good sign. A bad bearing will definitely show metallic color in the oil. I wonder if you have a cracked flywheel. It doesn't sound like a lifter to me, although hearing the car in person is much different than a video.

nubs4ck

This may sound stupid... but did you check your exhaust for a leak at the heads?

Schantin

iTrader: (6)

I have not torque checked the bolts since I installed them 3k miles ago. Possibility I guess, though it's awful "rattly" for an exhaust leak.

For lt1pwr1, installed a new LS7 clutch/flywheel 3k miles ago. Could be a possible cause.... Thought I'd be surprised if it died after such a short time.

If nothing else, glad to know this noise is stumping more peeps than just myself.....

More $0.02 appreciated.

BobP

iTrader: (1)

Got cats? Maybe some catalyst broke loose and is rattling around inside.

crainholio

iTrader: (2)

Disconnecting individual fuel injectors is a better way to approach this, so you don't contaminate your oil w/ gasoline.

Schantin

iTrader: (6)

Thanks for all the replies and suggestions.

Still haven't figured out WTF is causing this very loud tick/rattle. Dropped the car off at the port for shipping yesterday, so will tear it down once it gets back stateside next month.

BTW, I had to drive 28 miles from home to the shipping location. Car still drove smooth. I did note that the rattle/sound decreased significantly at 2200RPMs exactly (no good reason why that is...), and was loudest at start-up or when under a load (accelerating, going up hill).

Hoping it's something stupid like an exhaust leak, but I've never heard a nasty rattle like this from exhaust. Mentally prepping myself for the worst.

Will update in May when I get my car back.

Vortec53

Couldn't load the video..but I had a ticking in my 2000 5.3 that sounded just like you were describing. I was worried it was a lifter. Well I looked at it at idle this morning and saw a spark plug wire shaking. A couple of the plugs were loose so I tightened them and no more ticking. Just a thought

Schantin

iTrader: (6)

Good suggestion, but that's the first thing I checked. Sound is from the passenger side. I pulled every plug on the passenger bank...all were at 18lbs torque. Plug wear looked good too. Go figure. Car's in-transit to the USA now. Will "un-F" it once it arrives......

SunOfZ

iTrader: (3)

this post doesnt too old. so what ended up being the problem? i actually have a similar sound on my lq4.