Rattling sound when J30t is in Drive, or even Neutral

[Kiki1]

I've been having a problem with my J30t Infiniti for quite some time, and I've taken it to a dealership and other people and NO ONE can give me a straight answer on what it could be, and these are from people who have supposedly "looked" and "worked" and "fixed" my car.

So I'm willing to try another source to possibly get some answer on what the possible problems could be. Or if anyone even has a clue.

Ok, so here's the problem: Rattling sound when car is in DRIVE, or even NEUTRAL (but it has far less rattling then), but not in PARK. The Rattling sound has been going on for almost over 2-3 years now, and nothing seems to fix it, and no one seems to know what it is. It sounds kinda like a fan is loose or somethign along those lines, but I know very close to jack about cars.

Infiniti has about 136,000 miles on it. In the last 2-3 years I've had the AC replaced, the Camshaft sensor replaced about 3 times, my belts replaced, and general tune-ups. The car has a slight exhaust leak, but nothing major. I'm from Maryland, and I've had the car for about 8 years, and bought it used. It USED to run quiet as a mouse and now it sounds like a rattling tin truck.

Any ideas? I would appreciate any help or ideas at all.

Thanks,

Kiki1

[911/Q45]

Sounds like corroded exhaust shields near the mufflers or cats.

[infiniti tech]

Sounds like the front crank bearing is loose. There is a bulletin to replaced the #1 crank bearing with the tightest stock bearing available. It would sound like a knock most heard while in drive because of the trans load.

http://www.infinitihelp.com/Ow...6.htm

here is the bulletin
Modified by infiniti tech at 6:49 PM 9/13/2005

[DAEDALUS]

So that would show up as low oil pressure?

[elwesso]

Sounds like corroded exhaust shields near the mufflers or cats.

IM agreeing with that.....

Infiniti tech..... How do you go about replacing that, and is any damage being done to the engine?

[metaverse3]

It could be rocks in the catylytic convertor heat shield. Same issue that I just resolved a couple of weeks ago on my own J30... Get under the car and tap one of the heat shield and see if it clunks. Only way to remove it without removing the shield bolts is to blow pressured air through a nozzle until the rocks get blown out and the rattle goes away when you thump it.. Check it out..

[infiniti tech]

I have never replaced the main bearing for that complaint but I work with some tech's that have. I think there is a tsb on that complaint but I do not have it in front of me. It would need to be professionally diagnosed because of the nature and cost of the repair. It most likely would not cause any problems. To replaced you need to order the thickest grade of main bearing, drop the oil pan, remove the main bearing cradle, use the crankshaft to roll in a new bearing. It can be done without pulling trans.