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Catalytic converters can sometimes break and the pieces rattle around inside, I've had that happen to a different vehicle. Makes a rattling noise like some gravel in a coffee can.
There's 3 catalytic converters on the LS, there's one that joins the Y-pipe near the middle of the car and two that are closer to the engine that come right off the manifolds.
If you can easily hear the rattle inside the car , I would think any decent shop that can throw the car on a lift would be able to track it down.
True, the noise I have sounds exactly the same as a video of a car with a bad cat that I posted in another one of my threads. I've replaced all three of mine. The Lexus dealer in North Miami misdiagnosed the cats as bad a couple years ago, and you know how much money they want for those, so I have a hard time trusting a lot of "diagnoses" by techs when it's clear they're just guessing. The problem with this noise is that it can't be replicated on a lift.
Does your car make the clinking sound when you shift out of park? I noticed mine making the sound when shifted along with when I lightly press the accelerator.
Does your car make the clinking sound when you shift out of park? I noticed mine making the sound when shifted along with when I lightly press the accelerator.
No I don't notice a clink when shifting out of park. If it did then I would immediately suspect a u-joint.
Well when I have the car on the lift I can grab the driveshaft and if I pull on it back an forth (in the direction of the long axis of the car) there is play at the tail end of the transmission. The output flange at the back of the transmission moves a bit in and out of the case. If I am reading the parts diagrams correctly then I assume this should not happen; if the nut on the output shaft is tight then the flange shouldn't move. I compared it to another car, an '04 with only 70k miles and there was no play in the '04. Sounds like I will have to unbolt the driveshaft from the flange and check this nut. Anyone know what torque is specified for it?
Well when I have the car on the lift I can grab the driveshaft and if I pull on it back an forth (in the direction of the long axis of the car) there is play at the tail end of the transmission. The output flange at the back of the transmission moves a bit in and out of the case. If I am reading the parts diagrams correctly then I assume this should not happen; if the nut on the output shaft is tight then the flange shouldn't move. I compared it to another car, an '04 with only 70k miles and there was no play in the '04. Sounds like I will have to unbolt the driveshaft from the flange and check this nut. Anyone know what torque is specified for it?
Let me know if this fixes your issue because it will be the solution to mine as well.
Got to the garage today and disconnected the driveshaft to check the flange nut and it appears fine. It is staked and is not loose. Determined to find the source of this noise problem, I started playing with the driveshaft, knowing that the noise is coming from somewhere right in this area. When I grabbed the front half of the shaft and quickly rotated it back and forth the noise was clear. It rattled quite a bit, as if something was loose inside it. I grabbed the rear half of the two-piece shaft and the front half and found play in between the two shafts, and could feel a clunking every time I turned the shafts in opposite directions. I could detect movement where the two shafts are connected, so maybe the splines are worn? Also, what is the function of the large "driveshaft adjusting nut" that is on the front shaft near the center support bearing?
Thank you rkw. I read the entire thing and still don't know what is the function of the adjusting nut. I wonder if the female splined end of the front shaft is tightened onto the male splined end with this nut? If so, maybe it's loose? I didn't verify it's torque, I just checked it by hand and it didn't turn.
is taking the exhaust off absolutely necessary to change the center bearing?
I have a howling sound that is still prevalent after changing all 4 hub assemblies, so Ive ordered a center support bearing and will change that myself if its easy enough. If taking the exhaust off is required ill take it to my local mechanic.
is taking the exhaust off absolutely necessary to change the center bearing? I have a howling sound that is still prevalent after changing all 4 hub assemblies, so Ive ordered a center support bearing and will change that myself if its easy enough. If taking the exhaust off is required ill take it to my local mechanic.
You're correct. It works like a drill chuck grabbing on a drill bit. Here's another illustration... This makes me wonder how you were able to detach the drive shaft from the transmission without first loosen the adjusting nut - unless it was loose already!
Hmmm. Maybe I'll get it back on the lift tomorrow and see if I can check the torque on that nut. When I unbolted the front shaft from the transmission flange I was able to easily move it rearward to clear the transmission output shaft. I moved it rearward at least 1.5" and moved it out of the way. I guess this could only be done if the nut was loose! What concerns me though is the fact that I had a shop replace the center support bearing a while ago, and it had no effect on the noise. Weird.
Managed to get the car on the lift today. The driveshaft adjusting nut was indeed loose! I was able to get a large adjustable wrench on it and tighten it up without removing the exhaust. The crossmember and heat shield do have to removed though. I think I turned the nut about 180 degrees at the most. Sure enough, the driveshaft is now solid and the noise is gone. Blows me away that after four years, 50,000 miles, a dozen mechanics, at least $2000 in parts/labor, and countless hours of frustration it all came down to one loose nut. Unbelievable. Now I just hope it stays tight, if it keeps loosening I still might need to replace the driveshaft.
Managed to get the car on the lift today. The driveshaft adjusting but was indeed loose. I was able to get a large adjustable wrench on it and tighten it up without removing the exhaust. The crossmember and heat shield do have to removed though. I think I turned the nut about 180 degrees at the most. Sure enough, the driveshaft is now solid and the noise is gone. Blows me away that after four years, 50,000 miles, a dozen mechanics, at least $2000 in parts/labor, and countless hours of frustration it all came down to one loose nut. Unbelievable. Now I just hope it stays tight, if it keeps loosening I still might need to replace the driveshaft.
I am SO happy for you. Absolutely invaluable information. So glad you've found the problem... Now, why did that nut become loose????
01-21-15, 11:20 AM
