Brendan

22RE engine W56 transmission

When I am in 4WD and let off the gas pedal, I get a vibration or rubbing sound coming from either the transmission or t-case. It's likely the t-case since it doesn't happen in 2WD. It kind of reminds me of an engine brake on a semi truck (nowhere near as loud obviously). It is more noticeable the faster I am going, but really only notice it on the highway in 4th or 5th gear. When I am on the gas pedal, there is no abnormal sound at all. Any ideas? Thanks.

Co_94_PU

iTrader: (-1)

You are using the engine as a brake if you're not depressing the clutch, just not to the degree of a Jake brake... When in four high or low there is more load due to the gear reduction or combined forces of both axels.


Pinion or output shaft reverse thrust, you'll need to isolate if is front, rear or both.

You don't say what your driving but I'll assume it has manual hubs, disengage them will take the load off the front end if you have no change it's likely the rear end. Removing a propeller shaft and drive test will conclusively isolate it to either front or rear.
​
Low, no, or poor gear oil is an easy check. Not expensive or difficult to change that either unless you have trashed or frozen plugs. If you do nothing else change the lube, inspect for particles, start coasting with the clutch depressed, and stop using four wheel drive unless you are stuck and need to.

..
​​​​​​One of my previous owners severely abused or overlooked similar issues. To me it sounded like a jet reversing thrust for landing when I let off the throttle and started to engine brake (it's an automatic no choice but to engine brake without putting it into neutral). Inspection showed very bad gear oil, mixed oil water clay and sand aswell as a plugged diff breather. I changed out the gear oil and am saving up $ for new gears. There is still some growling but it's quiet enough you can hold a conversation (albeit a loud one, some of that is the snow tires ect)

Brendan

I do have manual hubs. My gear oil is redline MT90 that was fresh last year and topped up full. I'll look into what you have mentioned, thanks.

highonpottery

iTrader: (1)

Sounds to me like you're hearing your transfercase. It's very apparent when in low gear.
When's the last time you checked the oil level? Maybe it's just time to replace it. Don't get gear oil on your clothes, the smell = instant regret.

Charchee

Remove the front propeller shaft. Test in 4WD with hubs unlocked. If the noise is still there, start checking the driveline from the transmission to the rear end (including transfer case). Test in 4WD with hubs locked next. If the noise is back, inspect the front end. If you don't here it anymore at all, inspect the shaft and u-joints for wear. It could still be in either the output bearing from the case or the input bearing in the frond diff and it only shows up with the driveshaft installed but I bet you'll already be zeroed in on it by testing with the shaft out.

And by all means, double check your oil in all driveline components.

Co 94, I've got a front diff out of an 88 4Runner V6 Auto just laying around collecting dust. Hit me up if you think you might be able to use it.