Read end leak

[vetnut03]

I was wondering if any one can explain once and for all what is the cause of the C5 rear end leak. I have heard that it can come from the blow hole when the fluid gets hot, or from a leaking seal(s). The Anniversary forum has had a member poll on this and if I remember correctly over 70% of the members have had the problem. So why didn't GM make it an official recall? Thanks in advance.

[c4c5specialist]

HI there,
There are a few different issues.
First one, is the fact that many overfill the fluid, then as it gets hot the fluid aerates and is pushed out of the breather valve.
This is why you ALWAYS check the fluid level after you have driven 30 mins at highway speeds.
Second, the left side cover.
If its repaired per GM TSB, there will not be a return repair.
This requires anerobic sealer with new oring seal and axle shaft seal.
Out of all the ones I personally have done, I had 2 come back after the repair, due to MY misinstallation of the oring and getting the anerobic sealer ON the oring, which is a nono.
Allthebest, c4c5

[vetnut03]

Thanks c4c5. I haven't touched my fluid level at all so I am hoping it won't ever leak. Maybe that's asking too much but there's always praying I guess. I never miss your seminar at Carlisle but didn't get a chance to ask this then. So glad you are around. Bob

[1999 White C5 Coupe]

Originally Posted by c4c5specialist

HI there,
There are a few different issues.
First one, is the fact that many overfill the fluid, then as it gets hot the fluid aerates and is pushed out of the breather valve.
This is why you ALWAYS check the fluid level after you have driven 30 mins at highway speeds.
Second, the left side cover.
If its repaired per GM TSB, there will not be a return repair.
This requires anerobic sealer with new oring seal and axle shaft seal.
Out of all the ones I personally have done, I had 2 come back after the repair, due to MY misinstallation of the oring and getting the anerobic sealer ON the oring, which is a nono.
Allthebest, c4c5

c4c5specialist,

I am having a problem with my 1999 C5 coupe, A4 with the performance axle.

At 47,852 miles - I changed the rear differential fluid, using GM synthetic fluid and 4 oz. of additive.

The car drove fine for months with local driving - but after a long expressway vacation drive, the rear differential began to chatter when stopping and turning at 49,158 miles (when exiting the highway). I took the car to a Chevrolet dealer and the technician said there was TSB bulletin to add an additional 4 oz. of additive, then drive the car in several "figure 8's" to work in the fluid. The dealership performed the service and that immediately curred the chatter.

Now at 51,050 miles - the rear differential has a slight leak - about the size of a quarter on the floor after it is driven and parked.

I drove the car for about 45 minutes at highway speeds today, then parked it on level ground. When I began to remove the fill plug, fluid began to drain quickly from the fill hole, before the plug was fully removed.

Is the differential overfilled? Should I remove the fill plug and allow the fluid to drain? I am positive the garage floor is level. I suspect the fluid is now overfilled since the dealership added the additonal 4 oz. of fluid, and it is leaking out the vent.

Any suggestions? Thank you.

[c4c5specialist]

HI there,
Most likely, yes, your overfilled.
Allthebest, c4c5

[1999 White C5 Coupe]

Originally Posted by c4c5specialist

HI there,
Most likely, yes, your overfilled.
Allthebest, c4c5

Thank you.

[Junkman]

Well, if you ever have to do the repair yourself (because Lord knows, you'll do it right and won't have to make repeated trips to the dealer), here's your link.

[c4c5specialist]

Corvettemechanic.com does NOT, in any form, recommend following the procedure in this link.
This is strictly for an axle shaft seal and does NOT cover what we are talking about here.
Allthebest, c4c5

[froggy47]

Originally Posted by Junkman

Well, if you ever have to do the repair yourself (because Lord knows, you'll do it right and won't have to make repeated trips to the dealer), here's your link.

How's it holding up Junkman?

:)

[John H]

My local Chevy dealer performed the TSB related to replacing the left cover oil seal to fix a leak on my 10,880 mile 2001 six speed coupe. The repair has fixed the leak so far.

Question #1: How can I request that GM help to cover the cost of this repair? Question #2: As a result of the repair, the left side muffler and exhaust outlets are not aligned with the right side muffer outlets (they are 1/2" too low). How can this be corrected? Thank you,