Rear Differential Fluid Issue
Le Mans Master
Joined: Mar 2002
Posts: 5,955
Likes: 161
From: PNW
If it's over filled, it will just puke out the vent until enough is removed to stop the puking process.
Best thing to do is remove the fill plug when the diff is warm and let it drain until the level is at the bottom of the fill hole, then reinstall the fill plug.
Racer
Joined: Feb 2007
Posts: 296
Likes: 0
From: Landisville PA
We did ours a few weeks back. I used Amsoil SVG without any additional friction modifier. Filled it until it started coming out the fill plug.
Reinstalled plug, no runs, no drips (no errors).
If I was using a gear lube that required the friction modifier, I would have put in the recommended amount after the first quart was in. Then topped it off with more gear lube until it comes out the fill hole.
I wonder how they got it overfilled? Sounds like you were watching when it was done, so did they have the rear end way higher than the front of the car? That the only way I can see it happening.
Also, you mentioned in one post that you would need $60 for fluids and a washer... I don't think there was a washer on the fill plug or drain plug. Maybe that's the problem?
Reinstalled plug, no runs, no drips (no errors).
If I was using a gear lube that required the friction modifier, I would have put in the recommended amount after the first quart was in. Then topped it off with more gear lube until it comes out the fill hole.
I wonder how they got it overfilled? Sounds like you were watching when it was done, so did they have the rear end way higher than the front of the car? That the only way I can see it happening.
Also, you mentioned in one post that you would need $60 for fluids and a washer... I don't think there was a washer on the fill plug or drain plug. Maybe that's the problem?
Thread Starter
Team Owner
Joined: May 2004
Posts: 26,345
Likes: 232
From: SoCal
I don't think it would cause any seals to blow out or the vent to stick open if over filled. The vent is spring loaded, and the spring is always trying to keep it closed.
If it's over filled, it will just puke out the vent until enough is removed to stop the puking process.
Best thing to do is remove the fill plug when the diff is warm and let it drain until the level is at the bottom of the fill hole, then reinstall the fill plug.
If it's over filled, it will just puke out the vent until enough is removed to stop the puking process.
Best thing to do is remove the fill plug when the diff is warm and let it drain until the level is at the bottom of the fill hole, then reinstall the fill plug.
DH
Thread Starter
Team Owner
Joined: May 2004
Posts: 26,345
Likes: 232
From: SoCal
We did ours a few weeks back. I used Amsoil SVG without any additional friction modifier. Filled it until it started coming out the fill plug.
Reinstalled plug, no runs, no drips (no errors).
If I was using a gear lube that required the friction modifier, I would have put in the recommended amount after the first quart was in. Then topped it off with more gear lube until it comes out the fill hole.
I wonder how they got it overfilled? Sounds like you were watching when it was done, so did they have the rear end way higher than the front of the car? That the only way I can see it happening.
Also, you mentioned in one post that you would need $60 for fluids and a washer... I don't think there was a washer on the fill plug or drain plug. Maybe that's the problem?
Reinstalled plug, no runs, no drips (no errors).
If I was using a gear lube that required the friction modifier, I would have put in the recommended amount after the first quart was in. Then topped it off with more gear lube until it comes out the fill hole.
I wonder how they got it overfilled? Sounds like you were watching when it was done, so did they have the rear end way higher than the front of the car? That the only way I can see it happening.
Also, you mentioned in one post that you would need $60 for fluids and a washer... I don't think there was a washer on the fill plug or drain plug. Maybe that's the problem?
It was filled with car on drive over pit .... so it was pretty level.
I watched him put the whole 2 qts in.
There is a washer on the drain plug cause I just bought one from GM...part number is #12369215...it looks like it is aluminum.
DH
Premium Supporting Vendor
Joined: Aug 2001
Posts: 5,364
Likes: 38
From: King George VA
I don't think it would cause any seals to blow out or the vent to stick open if over filled. The vent is spring loaded, and the spring is always trying to keep it closed.
If it's over filled, it will just puke out the vent until enough is removed to stop the puking process.
Best thing to do is remove the fill plug when the diff is warm and let it drain until the level is at the bottom of the fill hole, then reinstall the fill plug.
If it's over filled, it will just puke out the vent until enough is removed to stop the puking process.
Best thing to do is remove the fill plug when the diff is warm and let it drain until the level is at the bottom of the fill hole, then reinstall the fill plug.
I'd open up the fill plug and check level, clean it up, then monitor it before I'd start to worry.
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Le Mans Master
Joined: Mar 2002
Posts: 5,955
Likes: 161
From: PNW
Go for a short drive - 10 miles max. Go park and let it sit for an hour or two, then go wipe all the suspect areas with your finger and look for any hint of leakage.
This is how I determined my leak was just vent over flow, which would run down the crack between the LH side cover and the diff housing. It would then drip off the bottom of the LH side cover, which is what a leaking axle seal would also do. But the LH seal was bone dry, and the area just below the vent was oily, thereby pin pointing the leakage source.
Thread Starter
Team Owner
Joined: May 2004
Posts: 26,345
Likes: 232
From: SoCal
DH
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Thread Starter
Team Owner
Joined: May 2004
Posts: 26,345
Likes: 232
From: SoCal
Best thing to do next is clean everything up again, including around the vent and everything below the vent area. Also clean up around the LH axle seal and LH side cover perimeter as well as possible.
Go for a short drive - 10 miles max. Go park and let it sit for an hour or two, then go wipe all the suspect areas with your finger and look for any hint of leakage.
This is how I determined my leak was just vent over flow, which would run down the crack between the LH side cover and the diff housing. It would then drip off the bottom of the LH side cover, which is what a leaking axle seal would also do. But the LH seal was bone dry, and the area just below the vent was oily, thereby pin pointing the leakage source.
Go for a short drive - 10 miles max. Go park and let it sit for an hour or two, then go wipe all the suspect areas with your finger and look for any hint of leakage.
This is how I determined my leak was just vent over flow, which would run down the crack between the LH side cover and the diff housing. It would then drip off the bottom of the LH side cover, which is what a leaking axle seal would also do. But the LH seal was bone dry, and the area just below the vent was oily, thereby pin pointing the leakage source.
Maybe it is done puking or maybe there is no gear oil left ..... I will have to try check it again tonight or it will have to wait for the weekend.
So you actually couldn't SEE up there ..... you just went by FEEL...right??
DH
Last edited by Dirty Howie; Jun 20, 2007 at 02:56 PM.
Racer
Joined: Feb 2007
Posts: 296
Likes: 0
From: Landisville PA
Anyone else want to venture a guess how the tech got 2 whole quarts in the diff while the car was level?
There's no way the extra .3 quarts stayed in there while he quickly put the fill plug back in. No way. It would have gushed out all over the place.
How did he get the fluid in the diff? Did he use a hand pump, or maybe a big syringe? It's pretty obvious when the diff is full, as it immediately starts running out the fill plug, unless he just kept pumping. Even so, there isn't an easy way to get it over fill, especially while it's sitting level.
Good luck, and I hope it's done puking all over the garage floor, and more importantly spraying on the back of the car.
There's no way the extra .3 quarts stayed in there while he quickly put the fill plug back in. No way. It would have gushed out all over the place.
How did he get the fluid in the diff? Did he use a hand pump, or maybe a big syringe? It's pretty obvious when the diff is full, as it immediately starts running out the fill plug, unless he just kept pumping. Even so, there isn't an easy way to get it over fill, especially while it's sitting level.
Good luck, and I hope it's done puking all over the garage floor, and more importantly spraying on the back of the car.
Racer
Joined: Feb 2007
Posts: 296
Likes: 0
From: Landisville PA
Racer
Joined: Mar 2007
Posts: 361
Likes: 0
From: Landisville PA
...and that's just a rule of thumb. Depending on the current condition of your seals - if they are slightly worn already.... that could become the path of least resistance.
Thread Starter
Team Owner
Joined: May 2004
Posts: 26,345
Likes: 232
From: SoCal
DAMN !!!!!
For the last three days I had no leakage or splatter specks on the rear of my car.
Then today the back of my car is all splattered and when I got out of the car there was a drip just falling off the diff.
Today it was warmer, 100 instead of 85 and the drive was 50 instead of 25 miles. And I went WOT more.....
I guess I will run it real hard and then when good and hot will check the level again.
I hope it just doesn't start pouring out or lockup ..... I am going to the track next weekend and no time to get it into the dealer.
For the last three days I had no leakage or splatter specks on the rear of my car.
Then today the back of my car is all splattered and when I got out of the car there was a drip just falling off the diff.
Today it was warmer, 100 instead of 85 and the drive was 50 instead of 25 miles. And I went WOT more.....
I guess I will run it real hard and then when good and hot will check the level again.
I hope it just doesn't start pouring out or lockup ..... I am going to the track next weekend and no time to get it into the dealer.
3rd Gear
Joined: Jun 2007
Posts: 3
Likes: 0
Hello Corvette Owners,
New to the forum. I purchased my 99 Vette September of last year. Car was a 1 owner 6 speed with 35,000 miles on it. Noticed right in the beginning that there was a chadder/shudder sound coming from the rear end when making left or right hand turns, like is described in this thread. Service manager from local Chevy dealer told me about a Service Bulletin to change rear diff. fluids to correct this problem. Had this done last fall before putting the car up for the winter (I live in beautiful Upstate New York). This seemed to take care of the sounds. When I put the car back on the road this spring I sarted to have the same problem. Took the car in to the Chevy garage the other day, and had the fluids changed again. Service bulletin says that 2nd change of fluids could take of problem. Getting same noise again. Service bulletin states that if does not work that the "clutch packs" may need to be changed?? I'm not a mechanic, looking for any feed back on this. Will driving it this way cause any more damage?
Thanks
New to the forum. I purchased my 99 Vette September of last year. Car was a 1 owner 6 speed with 35,000 miles on it. Noticed right in the beginning that there was a chadder/shudder sound coming from the rear end when making left or right hand turns, like is described in this thread. Service manager from local Chevy dealer told me about a Service Bulletin to change rear diff. fluids to correct this problem. Had this done last fall before putting the car up for the winter (I live in beautiful Upstate New York). This seemed to take care of the sounds. When I put the car back on the road this spring I sarted to have the same problem. Took the car in to the Chevy garage the other day, and had the fluids changed again. Service bulletin says that 2nd change of fluids could take of problem. Getting same noise again. Service bulletin states that if does not work that the "clutch packs" may need to be changed?? I'm not a mechanic, looking for any feed back on this. Will driving it this way cause any more damage?
Thanks
Premium Supporting Vendor
Joined: Aug 2001
Posts: 5,364
Likes: 38
From: King George VA
John,
This is a very common problem with the C6s right now. Many of them are having good results shifting to this fluid:
AMSOIL Severe Gear Extreme Pressure Synthetic 75w90 with one bottle of this: AMSOIL Slip-Lock Differential Additive.
I use the Severe Gear 75w90 in my 02 Z06 and have had no diff failures (other than the common left axle seal replacement) in several years of racing. I don't not use the extra bottle of the friction modifier as the AMSOIL Severe Gear comes with modifier already in it, but the C6 guys with similar problems to yours are using one bottle... some two.
Ordering info to benefit the forum is in my sig, or you can drop me a PM.
You car read a recent thread on the topic here:
http://forums.corvetteforum.com/show....php?t=1732382
P.S. Congrats on your new ride and welcome to the forum.
This is a very common problem with the C6s right now. Many of them are having good results shifting to this fluid:
AMSOIL Severe Gear Extreme Pressure Synthetic 75w90 with one bottle of this: AMSOIL Slip-Lock Differential Additive.
I use the Severe Gear 75w90 in my 02 Z06 and have had no diff failures (other than the common left axle seal replacement) in several years of racing. I don't not use the extra bottle of the friction modifier as the AMSOIL Severe Gear comes with modifier already in it, but the C6 guys with similar problems to yours are using one bottle... some two.
Ordering info to benefit the forum is in my sig, or you can drop me a PM.
You car read a recent thread on the topic here:
http://forums.corvetteforum.com/show....php?t=1732382
P.S. Congrats on your new ride and welcome to the forum.
Pro
Joined: Feb 2002
Posts: 606
Likes: 0
From: Virginia Beach VA
I use a new Aluminum Seal Washer at every drain and fill. I'm pretty sure they are one time use items, they’re inexpensive parts from the dealer.
While in the subject, I run Redline 75W90 without friction modifier and never have a problem with posi clutch chatter in over 50 diffs built over the years.
I pop the factory vent out, replace it with a fitting, and run a line up higher with a filter on the end of the hose. I fill’em up to the fill plug level.
While in the subject, I run Redline 75W90 without friction modifier and never have a problem with posi clutch chatter in over 50 diffs built over the years.
I pop the factory vent out, replace it with a fitting, and run a line up higher with a filter on the end of the hose. I fill’em up to the fill plug level.
Last edited by Roadrace65; Jun 23, 2007 at 07:44 PM.
Thread Starter
Team Owner
Joined: May 2004
Posts: 26,345
Likes: 232
From: SoCal
I use a new Aluminum Seal Washer at every drain and fill. I'm pretty sure they are one time use items, they’re inexpensive parts from the dealer.
While in the subject, I run Redline 75W90 without friction modifier and never have a problem with posi clutch chatter in over 50 diffs built over the years.
I pop the factory vent out, replace it with a fitting, and run a line up higher with a filter on the end of the hose. I fill’em up to the fill plug level.
While in the subject, I run Redline 75W90 without friction modifier and never have a problem with posi clutch chatter in over 50 diffs built over the years.
I pop the factory vent out, replace it with a fitting, and run a line up higher with a filter on the end of the hose. I fill’em up to the fill plug level.
I opened the fill plug today after driving the car for over 20 miles so it was good and hot. It was full to the bottom threads. So I am hoping it just starts puking when going very fast and hot.
Amazing that although I let the overfill out a few days ago and the back of my car is covered in oil specs and several drips on the garage floor that it was still completely full !!!!!!!!!!!!
Is replacing the factory vent something that can be done without dropping the rear end??????
I stuck my hand up the left side of the diff and felt a round upright is that the vent?? Is there a picture of exactly where and what this looks like????
DH
Thread Starter
Team Owner
Joined: May 2004
Posts: 26,345
Likes: 232
From: SoCal
Nice pics.....
How in the world could you take a pic with the diff installed.....unless you can see it with the wheel off.....I didn't try that
But that looks like what I am feeling on the top of the diff, towards the rear and right next to the left side plate. Is that correct??
DH
How in the world could you take a pic with the diff installed.....unless you can see it with the wheel off.....I didn't try that
But that looks like what I am feeling on the top of the diff, towards the rear and right next to the left side plate. Is that correct??
DH
Burning Brakes
Joined: Apr 2005
Posts: 1,123
Likes: 14
From: Booker Texas
Nice pics.....
How in the world could you take a pic with the diff installed.....unless you can see it with the wheel off.....I didn't try that
But that looks like what I am feeling on the top of the diff, towards the rear and right next to the left side plate. Is that correct??
DH
How in the world could you take a pic with the diff installed.....unless you can see it with the wheel off.....I didn't try that
But that looks like what I am feeling on the top of the diff, towards the rear and right next to the left side plate. Is that correct??
DH
I took the pictures when I had the exhaust removed! Took about 10 pictures before I was happy with what I had!
As you can see the vent is pressed in there.
Good luck!!!