Chattering or clanking noise from tranny area!

[Webster3]

I just started hearing this strange "chattering" from right under the center hump. I have an auto transmission. Here are the symptoms:

1. The noise is related to movement of the truck, not related to engine RPM.

2. The noise begins shortly after driving cold... it gets louder as the truck warms up and eventually is a load clanging that you can feel through the gas pedal.

3. If I rock the vehicle side to side I can get it to make a light clank, rocking up and down does nothing. It seems to be most active when the truck "twists" a bit as you go over bumps.

4. The noise sounds metallic, and sounds like something that is tight on one side but loose on the other... so the loose item is almost "flapping" as the truck bounces around.

I inspected everything visible under the truck. The only thing loose was the heat sheild on the side of the transmission and pushing that back into in and getting the clips tighter didn't help.

Its hard to tell, but the sound seems to be coming from right above the transmission pan... either inside or right above it where I cannot reach.

I hope that is enough info for someone with knowledge to help me diagnose this issue. I'm hoping its not even related to the tranny. In fact, there seems to be no problem with the operation of the transmission... shifts quickly and smoothly... goes into all gears fine and I checked the fluid and its fine.

Please let me know if you have any thoughts.... I sure would like to figure this out before something breaks!

Ed

 

[checkedout]

Flywheel?
http://www.explorerforum.com/forums/showthread.php?t=137703&highlight=cracked+flywheel

 

[Webster3]

Doesn't sound quite the same... with my sound there is no connection to the engine speed or even the speed of the truck down the road. Once I'm warmed up I can hear it clanging as much from going over the bump in my driveway as hitting a pothole at 55.

Thanks!

Ed

 

[Webster3]

Someone at work suggested a loose emergency brake cable. I haven't had a chance to physically get under there and check it but I tried applying the e-brake as I was hearing the noise and it didn't stop it.

Anyway, any other ideas on this.... I am starting to worry that my tranny is going to drop out or something!

Ed

 

[Webster3]

I have some new info that perhaps could spark something....

I discovered that the metallic clanking noise goes away if I am turning to the left and is worse when turning to the right.

It doesn't seem to be related to the compression of the front shocks or springs because the sound is still there during braking. It seems to be the torquing or twisting motion that occurs in a turn that has the effect.

Here are some things I'm considering:

I checked the mount for the tranny... but that was solid. Then I thought about the motor mounts. It was dark by the time I was looking last night so I couldn't get in enough to see them, but apparently if I put the truck on stands in the front and the gently jack up the engine a bit I should be able to check the motor mounts. If the rubber in there is completely gone on one of them perhaps it could account for this noise?

Here is the one caveat with this threory... I would have expected the noise to appear while revving the engine if its a motor mount right? Or is my V6 just not delivering enough tourque to do that?

Any ideas with this new info?? What do you think of my motor mount theory?

Ed

 

[BrooklynBay]

Check your exhaust hangers, as well as all of the exhaust parts. Sometimes there could be a little vibration from a sheet metal flange heat shield on the vehicle's underside. The exhaust could rock to one side when making a turn, but not rock when you turn the opposite way.

 

[Webster3]

Yeah, one of the shields is actually loose, but the sound is much different that that sound (which I know well). This sound is coming from closer towards the front and is a "thicker" sound... meaning it feels like a heafty metallic clanking rather than the chattering of thin sheet metal.

Here's a summary of the symptoms:

1. Metallic clanking that is coming from under the floorboard and specifically can be felt through the gas petal.

2. Noise usually is quiet or missing when cold, but increases as the vehicle warms up.

3. Noise is present when going straight, worse when turning right and stops during left turns.

The best way to describe how this sounds and feels when it gets going is that its like having a piece of 3/4 inch steel attached to my frame with a loose rubber band.

Thanks!

Ed

 

[checkedout]

I still think flexplate. Any updates?

 

[Glacier991]

I'm curious about the drivelines and U joints.

 

[Webster3]

I still have no answer. I bought an 01 Maxima as a daily driver and just started a new job so I haven't had a chance to due further troubleshooting.

How would I check the U-joints?

Ed

 

[BrooklynBay]

Take out the U joint, and see if there is excessive play on the end caps. A lot of times you will see grease leaking out in those areas.

 

[Webster3]

Any threads here that deal with that procedure that you know of off hand? Or will my Haynes manual probably cover that well enough? Never messed with u-joints before

Ed

 

[BrooklynBay]

Here is a thread written by ExplorerDMB: http://www.explorerforum.com/forums/showthread.php?p=1320764. He always has very useful how to articles in his list under his user name.