Will it rattle even when gas is applied in idle? Im getting that famous rattle at 1500-2500 rpms and sounds like its coming from the middle of the car. NO START UP RATTLE - brand new engine so Im assuming it wont be the timing chain also.

I searched but found no definitive answers on symptoms of cat failure. thanks in advance

 

cat failure.... smells like rotten eggs

Thats just one symtom.. i'm sure theres more

 

Pull the cat and precats. If there are chunks loose/missing, then that is the source of your rattle. If the are all intact, then its your engine again. Pulling them is the only way to tell.

 

ahh could it really me the engine again when it only has 800 miles on it? Oil level is good btw

 

Why not check the cats and then ask that question.

 

check the flex section in the y-pipe. I had the stock flex break loose, and then also the original flex on my Cattman y....

it will make the rattling sound if that happens.

 

cool thanks I will give it a try. Ahh and if thats not it then that means engine problem..again?!? what are the chances of that...

I feel like selling this car..every week a different sensor is keeping me busy and now this...ill post up what happens

 

Please take mtrai760 advice please. irish44j's method doesn't verify if the cats are fried.

Verify before asking that question again because we cannot answer that unless you do.

 

i also have a rattling i was told by 2 muffler shops that the flex section is bad and i can visually see myself its pretty shot told the dealer twice n they says its fine. im just dealing with it for now til i can afford some cattman

 

Signs of a bad cat could include power loss under acceleration, difficulty starting, decreased milage. My guess would be its your flex section though unless you have any of the above symptoms. mtrai760, a cat would have to be so f ed up to have chunks missing or lose that he would have a major power loss by that point.

 

My method eliminates a more likely possibility first. Another likely source of such a rattle is the cat heat shield (which many of us have had rattle). If both of those are good, THEN move on to the cats...

Why would you suggest that he check the cats FIRST (at considerable effort) before checking the flex pipe and the heat shield, which would take him about 2 minutes to check?

Logic > you.

 

At least someone has common sense in here.

 

Either way, he should stop posting and get under the car first, which was my point.

Context > you.

 

touche'

10char

 

my mechanic shaved a little off the heatshield before the cat more towards the engine...is this the precat? Either way the heat shield was making contact w/ one of the beams under the engine and he said that could possible cause the rattling. All I know is it had a heatshield over it so Im not sure if it was a precat.

The rattle is still there but not as much...guess its something I should live with..

 

im taking it to nissan tomorrow...ive had it w/ this noise

 

I'm guessing it's the y-pipe heat shield rattling against the brace under it if you say it's touching...why not just get under there yourself and remove the heat shield and try bending it? it's held on with like 4 10mm bolts....

 

update: it was my motor mount...nissan is replacing it. They tested it and said thats the culprit