The Ever Elusive Noise
#1
The Ever Elusive Noise
As some of you might know, I've been chasing a rubbing/grinding/whooshing sound for the past few months and nobody can figure it out. It seems like it first started when I towed a heavy load a few months ago. It became much louder and more obvious when I took a trip to the mountains a couple weeks ago.
The noise seems to be coming from right under the cab (transmission area). It can be felt in the floorboards and is reminiscent to the sound of air whooooossssshhing under the truck mixed with a rubbing/grinding sound. When it got really bad in Tahoe it started to make the noise around my transmission shift points althought that could have been a coincidence, because the transmission still shifts GREAT, never slips or hunts for gears. It also seems to only make the noise when the truck has been driven for 30 minutes or so (meaning it is heat related).
I have taken apart my transfer case and the internals looked good. The u-joints are new and still move very freely. All the fluids (tranny, t-case, differentials, engine oil) are very new.
I'm at a loss here, nobody can figure out where this is coming from, including a professional at a transmission shop.
Last night the sound came back. When I let off the throttle at 30 or 40mph it would coast, but the RPMs did not drop and I could hear the rubbing sound coming from under the truck again. It would continue to make the noise until I accelerate again or until I depress the brakes, at which point the RPMs would start to drop as normal. It was almost as if the truck was trying to ride the gear down like a manual transmission would. I'm thinking it is the torque converter but I have no clue. Maybe gear howl from the rear diff? Any ideas are appreciated. Sorry for the long post.
The noise seems to be coming from right under the cab (transmission area). It can be felt in the floorboards and is reminiscent to the sound of air whooooossssshhing under the truck mixed with a rubbing/grinding sound. When it got really bad in Tahoe it started to make the noise around my transmission shift points althought that could have been a coincidence, because the transmission still shifts GREAT, never slips or hunts for gears. It also seems to only make the noise when the truck has been driven for 30 minutes or so (meaning it is heat related).
I have taken apart my transfer case and the internals looked good. The u-joints are new and still move very freely. All the fluids (tranny, t-case, differentials, engine oil) are very new.
I'm at a loss here, nobody can figure out where this is coming from, including a professional at a transmission shop.
Last night the sound came back. When I let off the throttle at 30 or 40mph it would coast, but the RPMs did not drop and I could hear the rubbing sound coming from under the truck again. It would continue to make the noise until I accelerate again or until I depress the brakes, at which point the RPMs would start to drop as normal. It was almost as if the truck was trying to ride the gear down like a manual transmission would. I'm thinking it is the torque converter but I have no clue. Maybe gear howl from the rear diff? Any ideas are appreciated. Sorry for the long post.
#4
Originally Posted by Skandocious
It was almost as if the truck was trying to ride the gear down like a manual transmission would. I'm thinking it is the torque converter but I have no clue.
#5
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#8
Originally Posted by Skandocious
I'm not sure I've ever heard of a locking torque converter... And how could any car remain operable after "disconnecting" the torque converter?
Anyhow, I don't believe I have a locking torque converter. This is the stock converter...
Anyhow, I don't believe I have a locking torque converter. This is the stock converter...
Added on edit: The reason I suggested this is because a friend of mine had a Chevy where the lockup converter stuck. The RPM stayed up with the vehicle speed just as a manual would, and when coming to a stop the car started bucking and making sounds/vibrations similar to a slipping clutch until the trans finaly stalled the engine. You wouldn't have gotten the bucking because you weren't coming to a stop, but if the sounds and vibrations seemed similar to that of a manual trans with a slipping clutch then the converter may be the culprit.
Last edited by ec_fritz; 07-31-2007 at 08:42 AM.
#9
Originally Posted by Skandocious
Not sure, haven't tried that yet. It's really hard to produce the noise when I want to, it just comes and goes as it pleases... Why do you ask?
#10
Yeah I think I saw your u-joint, and mine are brand new so I don't think that's the problem. Not to mention the fact that I just had my driveshaft off when I dissembled my transfer case and I rechecked the u-joints and they were fine. I WISH WISH WISH I could fix this problem with a simple u-joint
And as far as I know, these E4ODs do not use an electronic locking clutch... But I've been wrong before...
And as far as I know, these E4ODs do not use an electronic locking clutch... But I've been wrong before...
Last edited by Skandocious; 07-31-2007 at 01:31 PM.
#11
Did you check the rear end? The differential could be passing that sound transfer through the driveshaft. Aren't there bearings in the housing of the diff case? I'm just trying help you think of what wrong. Put it seems that it's harmonic, which could mean that the problem isn't where you hear it...Make sense? I know I 've had trucks that made the exact same noise when I let up off the gas...It ended up being an axle being worn, and when the torque was released off the driveshaft and it could basically just coast, I would hear it, but under acceleration it would go away...
#12
#13
Originally Posted by 94broncoxl
Shot in the dark here, I know some f150's have them not sure if yours does. Hanger bearing on the rear driveshaft possibly. Those have been known to make some darn near impossible to diagnose noises/vibrations, especially at certain speeds or rpms.
#14
He's got a carrier bearing under his truck, but I think it's been replaced recently as well.
He's also got an E4OD, which does have a locking torque converter. I really don't know that much about automatics, so I don't know if it's the torque converter or not. I can't really imagine how a converter would make a whooshing noise though.
Personally, I am leaning towards it being the rear axle. Possibly a carrier or pinion bearing, or maybe the gears themselves. I think it just *sounds* like it's coming from further up under the truck.
He's also got an E4OD, which does have a locking torque converter. I really don't know that much about automatics, so I don't know if it's the torque converter or not. I can't really imagine how a converter would make a whooshing noise though.
Personally, I am leaning towards it being the rear axle. Possibly a carrier or pinion bearing, or maybe the gears themselves. I think it just *sounds* like it's coming from further up under the truck.
#15
Andy's right, I just replaced the driveshaft center support bearing.
But the sound is coming from more near the FRONT of the transmission near the TC. If the sound really is originating in the rear end I'm not sure how it could get all the way up to the front of the transmission, but what the heck do I know. How much does it usually cost to have a differential rebuilt?
But the sound is coming from more near the FRONT of the transmission near the TC. If the sound really is originating in the rear end I'm not sure how it could get all the way up to the front of the transmission, but what the heck do I know. How much does it usually cost to have a differential rebuilt?