hissing type noise from rear end when cornering
Thread Starter
Heel & Toe
Joined: Oct 2020
Posts: 19
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hissing type noise from rear end when cornering
hey guys, i just changed my rear diff fluid and trans fluid with redline fluids and now when going around corners i notice a hissing type noise that sounds like its coming from the rear end at light throttle only when cornering. i don't remember hearing the noise before the fluids change but i also have the trunk carpet removed now and i didnt before and only drove the car acouple of times before as i just purchased it recently and have ben going through it. i did figure 8s and multiple 360s after performing the diff fluid change and just noticed this noise after 100-150 miles. i never really herd anything like it before, it almost sounds like pressure inside the diff case hissing, when i removed the fill plug when doing the change the diff had a ton of pressure in it still after not driving for 2 to 3 weeks also. when drive the car hard i also get a smell that smells like gear or trans fluid after wards not sure if its related. after driving hard i do notice a very small amount of seepage on the bottom left side of the rear diff where it meets the side cover do i have i problem with my vent? is it normal for the rear diff to hold pressure so long? and could that be causing a hissing type noise corner i appreciate any input, thanks guys!
Thread Starter
Heel & Toe
Joined: Oct 2020
Posts: 19
Likes: 0
Tech Contributor
Joined: Dec 1999
Posts: 32,910
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From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
jgt8229
Your diff has a small vent valve on the top of the differential. Its a metal tube with a small metal cap on top of the tube. The cap may be a little loose and rattle a bit. That's normal.
Inside the vent is a little rubber disk that is held down with a little spring. The rubber disk should allow any excessive pressure to easily vent BUT when the differential cools down, it should seal and allow the differential to sit under a very slight vacuum.
When you remove the fill plug, you should hear a very slight IN RUSH of air to release the vacuum.
You should NEVER see pressure inside the differential case. If air rushes out of the fill plug, there's a problem. If so, that vent valve is stuck shut.
Yes they can be replaced and or removed and cleaned.
Get a mirror and a flashlight and see if you can locate it.
Bill
Your diff has a small vent valve on the top of the differential. Its a metal tube with a small metal cap on top of the tube. The cap may be a little loose and rattle a bit. That's normal.
Inside the vent is a little rubber disk that is held down with a little spring. The rubber disk should allow any excessive pressure to easily vent BUT when the differential cools down, it should seal and allow the differential to sit under a very slight vacuum.
When you remove the fill plug, you should hear a very slight IN RUSH of air to release the vacuum.
You should NEVER see pressure inside the differential case. If air rushes out of the fill plug, there's a problem. If so, that vent valve is stuck shut.
Yes they can be replaced and or removed and cleaned.
Get a mirror and a flashlight and see if you can locate it.
Bill
Last edited by Bill Curlee; Dec 4, 2020 at 05:34 PM.
