NEED HELP!!!! Weird Sound.....?????

[BigJohn]

2005 Nissan Altima, auto transmission We are getting a weird sound from the engine compartment area. It could be coming from the tranny/drive train....but don't think it has anything to do with the engine. Here's the deal.... The vibration & sound starts at about 30mph and seems the loudest at about 40-45mph. This sound is apparent when driving down the street. When the vehicle is in park or neutral and we rev it completely through the RPM range....no sound when still. One test we did...we rolled the car up to 45 mph...and let it coast in neutral and the sound is present, then disappears at about 30 mph. This sound has appeared about 6 months ago and we have been driving the car on a daily basis. We mounted and balance new tires and did a new alignment....which did not eliminate the sound/vibration. Can anyone help?????

 

[Dr_No]

Is it possible that your heat shield is rattling around?

 

[BigJohn]

 Originally Posted By: Dr_No

Is it possible that your heat shield is rattling around?

That's a good guess, but I would think if it were the heat shield, then that sound would arise with a simple rev in RPM's while in park. This sound only happens when the car is moving. Another person has suggested that it might be the axle bearing on the front wheel drive. I just couldn't see that happening....over 6 months. Any drive or axel bearings I have ever been involved with....well, when they start to go...they go very, very quickly. At first, I thought it was the tranny. But then the sound is just as persistant when the car is coasting in neutral at 40 mph, at only an idle. Is there something in a front wheel drive system that I am overlooking that could be making this vibration/noise?

 

[oilyriser]

What does it sound like? Does the pitch change predictably with engine or vehicle speed? Does it happen on a windy day when the car is parked and shut off?

 

[Boomer]

Could it be a tranny bearing?

 

[Bambam]

CV joint

 

[hate2work]

Late model Altimas are known for heat shield rattle. Try this, as suggested by another member a couple weeks ago in response to a similar question. Locate the heat shield, take a ball of aluminum foil and wedge it under the shield, then test drive it. If the first place you put it doesn't change the noise, try this in a few different places and see if you can get the noise to stop. The idea of course is that if you can get the noise to stop/change, then the heat shield is the problem and you can get it repaired, possibly under warranty.

 

[BigJohn]

The best idea is to have our Tranny guy take a ride with us.