Transmission/T-case noise on decel

[mckennar]

Auto trans, 4x4, V6, happens when decelerating in gear on the highway. Noise is coming from the trans/transfer case area (not the rear end). Noise is persistent through a rear end swap and rear driveshaft swap. Also persistent through an Auto trans fluid change.

Temperature independent - i.e. it happens in all temps / all conditions with the atf cool and warm.

If I lift throttle at freeway speeds, I'll hear it. Accelerate or maintain speed, noise goes away. If I hit OD off, the noise changes in pitch. Drop the selector lever into "2" and the engine noise is too loud for me to hear it. Once the engine pipes down, I'm going too slow to hear it.

Transmission in neutral, noise goes away.

Transmission has 343,000 miles on it and shifts just as firmly/holds gears as well as my 180k transmission.

Reminds me of bearing noise from a manual trans but not gear whine.

Tried to get it on video but the mic on my potato phone picks up literally every other noise except the one I need it to.

Now for the question: Is there a chance it's the t-case? Fluid is full and fresh in the t-case, and 4wd works as expected without excessive noise in hi and lo. I do have a spare t-case but before I go swapping I want to make sure... I'm running out of "garage time" credits with the wife.

Thanks.

 

[jgue467]

Have you checked the two bolts holding the t-case dampner in place? They s/b at 28 ftlbs. Mine got loose after climbing the rockies on i70 west of denver, rattled at different times too till i tightened them. Luck. :cowboy:

 

[mckennar]

Have you checked the two bolts holding the t-case dampner in place? They s/b at 28 ftlbs. Mine got loose after climbing the rockies on i70 west of denver, rattled at different times too till i tightened them. Luck. :cowboy:

Good thought - I replaced the dampener when I first got the truck with a spare from my parts truck - the rubber had separated and the whole thing was just kind of dangling around in there. Thought it was an exhaust heat shield for the longest time until I was kicking the exhaust while laying under the truck and I watched the thing dance around, metal on metal.

The sound I'm hearing doesn't sound as loose/rattly as the thing did when the dampener... more wheel bearing than loose heat shield.

I think I know where this is going... heh. Going to have to cash in some of my garage hours on swapping the t-case instead of installing the 881s/906s and 5100s I just picked up. Boo.

Anyway, thanks for the reply, when I figure out what this racket is, I'll update the thread.

 

[mckennar]

Small update: I swapped 906s for 890s. Installed 881/890s (and LBJs, OTRs, front/rear endlinks etc etc) yesterday morning. While I was down there I dropped the t-case on my driver and my parts truck. This morning/afternoon I installed the t-case from the parts truck into my driver and did a fluid change while I was in there.

The noise? Remains (but hey, the 4wd shifter doesn't vibrate anymore). So, probably the transmission making the noise. When/if I do that swap, I'll see if I remember to update this thread.

 

[T4R2014]

The pitch change when hitting OD off makes me guess that your torque converter is the culprit.

 

[mckennar]

The pitch change when hitting OD off makes me guess that your torque converter is the culprit.

Either the TC or the trans still requires me to drop the trans... if this isn't a danger of sudden, catastrophic failure, I'll just run it until it's too loud for me to stand.

The noise I'm hearing sounds similar to what manesfesto's sounds like when he's on throttle in the first video. Mine happens off throttle.

manesfesto's thread:
http://www.toyota-4runner.org/gener...rque-converter-massacre-pics-need-advice.html

 

[trimyota]

Any update?

I am experiencing the same noise on my 89 4runner when taking my foot all the way off the gas at highway speeds. Did you ever figure out if it was the torque converter or somehting else? If I'm not mistaken, we both have the 340H tranny?
I only experience it over roughly 50 mph.

 

[Riceye]

Just something to try and it costs you nothing. Grab your grease gun and lube your driveshaft(s). This can take a few or several attempts if the joints and slip yoke have dried out.