Rustysocket

So I was underneath the car trying to figure out what exhaust system is installed on it and I noticed what appears to be a small hole in the differential casting above the fill plug. I have searched here and cant find any real good pictures of the rearend to see if this is normal or not. There is no fluid seepage or evidence of. 2007 C6 Z51 A6 if it matters.

Thanks for any help.

Racer

Don't think that is a factory cut hole, it looks to sharp edged and wierd.
I would put a piece of masking tape over it and spray it silver and don't look at it again.

Rustysocket

Yeah, that's what I figured to0. Should I use factory paint or do you think some duplicolor from wal-mart would work as well.

I typically spring for the good stuff like 3M tape as well... since this is an emergency do you think the the regular stuff will work ok?

I should have just forgotten that the car doesn't have stock exhaust and not worried about it.

Racer

DSOM

What it looks like to me is the bottom of the hole they drilled for the bolt threads went below the casting so it broke thru. Nothing to worry about imo.

calemasters

Looks like a case stress crack to the left of the hole.

Rustysocket

Seriously though,

I did find this picture in post 1 of this thread that appears to have a similar hole

http://forums.corvetteforum.com/c6-c...s-for-faq.html

Racer

Nice catch, I would say it is NOTHING to worry about. Just GM's sloppy work, I should check my wifes A6 Vette when she gets home.

Rustysocket

No there's no crack. When I uploaded the photo I saw that to and was like wtf.. it's just the angle and magnification and a shadow from the casting. Just got back under. It looks like I can see threads from the side cover through the hole.

can anyone else bother to post a photo or does my OCD have to keep me up for the next two weeks worrying about this.

Rustysocket

Would appreciate it if you don't mind.

Racer

Not my wifes but is that the little hole lower left of pic?......

R&L's C6

Is that the area behind the right muffler above the differential filler hole?

Rustysocket

Exactly... I have no mufflers so it was much easier to get up in there for the picture, hadn't thought about that.

Rustysocket

No... that picture is of the top of the diff.

The photo I posted is as you would look at it from the back of the car. The area is right above the diff filler hole.

Rustysocket

Here is a larger photo showing a better view of the area.

bolivar

Is the differential vented anywhere? Aren't most vented?

This looks to me like the bolt hole was drilled thru there.

Easy Rhino

What needs to be understood is whether there is a through-hole from the exterior to the interior of the case, which could allow the differential fluid to be contaminated.

The other consideration is whether or not there is an overall porosity that could result in weakening the case.

I would probably back that fastener all of the way out and use a high intensity light to try to determine if I could see into the case.

In either case, I would have the dealership look into it, if for no other reason, to get it documented. Make sure that they understand and document your concerns, and provide a written opinion.

If it breaks later, they could be on the hook to make it right if they touched it before the warrantee expired and did not fix it.

NavyVette89

Looks like when they drilled the initial holes in the case they just went to deep on that hole and it punched through. Nothing to worry about IMO.

glenB

Really !!! Some of the responses here ......

That's the result of drilling the hole that's then tapped for the bolt. It's very common and is not sloppy machine work or any assembly line screw up, all the manufactures have these, not just GM

Since the vehicle is 5 years old and hasn't failed or leaked ........

Don-Vette

Bingo!