Fluid leak in the rear axle area

[vms4evr]

Hey folks,
I appear to have a fluid leak but for the life of me I can't find it. And all my fluid levels are good! Oil, trans, cooling, p.s., brakes are all at the full level.
A couple of months ago I replaced my rear gear fluids (a messy job). And some did get on the exhaust pipes right before where they split off in a Y to the mufflers.
There is some oily mess on the top of the exhaust pipes, the very back end of the driveshaft, and the bottom of the compartment that houses the ASR computer.
I wiped it off and it looks and feels like brake fluid. Oily, light brown, not very strong smell. But my brakes work just fine.
I put engine cleaner and degreaser on everything, scrubbed it down with a scoth bright pad and then hosed it off. Not perfect but much cleaner.
Looked all over the back end and followed brake lines, gas lines, etc... and none appear to be wet or leaking. I also double checked the gasket around the rear axle and it is not leaking.
Am I freeking out or is there something else I should be looking for to try and hunt this down?
Graham

 

[Ken]

Did ya check your pinion seal Graham?

_ken

 

[BlackNBlue95]

Can you take some pics of this leak? Also if it is gear lube most often it will have a distinct smell kinda like sewage. From your description it almost sounds like a leak coming from the ABS/ASR Unit light brown fluid with the consistancy of water sounds like brake fuild to me.. btw brake fluid has a real bitter taste to it.. don't ask about that one but when you work on daily drivers/beaters for a living you get to taste alot of fluids..

Umm how long has the car been sitting that you noticed a leak?
and if you havn't I would check and see if there is any evidence of a leak after you have cleaned the area off let it sit for a while.

Your brakes can still feel fine and you could have a small leak some where.. I've seen it.. but usualy you would have to add some fluid every so often aswell..

-Rick

 

[vms4evr]

Ken,
Do you mean the rear axle cover? If so yes. The guy that changed my gears did a good job from what I can tell. The rear axle area is clean with no oil.

Rick,
I've tasted fluids before by mistake, having my head in the wrong place, but never brake fluid... The consistency is definetely like brake that of brake fluid. That 90W gear oil doesn't appear to thin to me when it is just laying around. It definetely looks like the bottom of the ABS/ASR box. But I have added no brake fluid in months and the fluid reservoir is at the full level.
Is it possible for the ABS/ASR to leak fluid without it affecting the main reservoir? Like maybe choking off the back brakes and they are dry and not working? The car seems to stop fine and not noticeable different than usual. I'm kinda stumped. I'll get under there during daylight and try and snap a few picks.

Graham

 

[BlackNBlue95]

I honestly would think the same thing that the fluid resivoir would not be full if there was a leak but I can't say with out looking at it. Well we'll see what we think once we see some pics of it.. I hope I can help you figure this out.. is this vette being stored in a garage? and how often do you drive it?

 

[BlackNBlue95]

Oh btw did you take a look in the ASR/ABS compartment too see if anything was wet at the bottom of the compartment? Just came to mind..

 

[vms4evr]

Rick,
No I haven't pulled that cover. I wasn't sure what would happen when I pulled it so I figured I would ask first. Never seen the inside of that box. Was hoping I never would ...
I found my portable floodlight. So I crawled under and took some pics. I beleive I have them sized down enough to get in here. So I'll post a couple as seperate replies.
Graham

 

[vms4evr]

Second pic of the ABS/ASR area from a different angle.

 

[vms4evr]

Here's a shot of the exhaust from the other side.

 

[vms4evr]

Here's a shot of the exhaust from the other side.

It would help if I actually sent the picture, duh... long day...

 

[Ken]

Ken, do you mean the rear axle cover?

No. The pinion is the gear that enters the differential from the front; it has a seal to prevent fluids from leaking. If this seal is worn, the gear oil will usually just seep from the pinion shaft area and show up around the front underside of the differential.

_ken

 

[BlackNBlue95]

Hmm nice pics... I have 2 more questions or comments.. 1 are the bolts at the bottom of the ASR Compartment damp? and two maybe it's your trans seal if the trans fluid could be dirty and it will look brown instead red.. it will feel oily but real thin not like gear lube.. and the reason I say this is in the pics the pinion seal at the front of the diff is dry.. and the rear seal on the trans has an extra lip on them so that it doesn;t sling oil around when it goes it just drips down onto the rear trans brace.. try to feel the brace closer to the trans and see if it has any residue on it.. you may just need to replace that thats my guess for now...

 

[jeepie]

My guess is it looks like the pinion seal. Sometimes when that leaks it can throw the oil all over, clean the area up and put a few miles on and you should be able to see if it is coming from the pinion seal. One other note, there is usually a vent on the top of the differential that can become blocked and this will force the fluid out through the seals. My diff was leaking on to my pipes, turns out some of my diff case bolts were loose, torqued them and the leak stopped.
Good luck.

 

[vms4evr]

Ok. Good stuff guys. To answer some questions...

The car is a daily driver and 5 days a week it carries my butt to work Sits most weekends.

I got it on the pinion seal part now, i think. This seals the diff in the front where the drive shaft goes in to the pinion???
Looked at this really close and could not see any oil. But there is a cover that spins around and hides a really good look at that area. Now if the fluid was weeping out then this little collar or whatever it is would sling gear oil around and then drip when parked wouldn't it? Also, what is this vent hole in the diff? I thought the whole carrier was sealed?

I cleaned the heck out it again last night after I took the pics. Some of the bolts that hold the ASR/ABS unit were wet. The inside ones next to the drive shaft. The outer ones were bone dry. There is some fluid on the ladder bar device that connects the tranny to the rear diff. But only next to the diff. There is no fluid leaking from the diff plug for adding fluid. All the bolts on the back diff carrier that I can see are bone dry. I did notice a small stain on top of the diff on the body. Would look like it got slung up there.

I changed my tranny filter, gasket, and put new Mobil 1 Synthetic tranny fluid in it a couple of weeks ago. So the tranny fluid is now nice and red. The level is where it should be. The pan is on good and no leaks. I'd be able to tell if it was tranny fluid. And I know what it tastes like Rick :L

One note. I pulled the diff plug and checked the diff fluid. It was low. I filled it with fresh Red Line Symthetic gear oil months ago after my gear breakin (changed 2.59 to 3.54). I ended up having to add about 4oz more last night. That doesn't seem like much but that crap is messy and does stink like sewage...

That's where I am so far. Will check it tonight after I get home from work and see if anything pops out at me.

Graham

 

[vettn94]

No. The pinion is the gear that enters the differential from the front; it has a seal to prevent fluids from leaking. If this seal is worn, the gear oil will usually just seep from the pinion shaft area and show up around the front underside of the differential._ken

Like this:

if you look closely, above and to the right of the 2 bolts going through the C-beam, you'll see a drip of fluid on the front outer lip of the pinon yoke.
The seal itself actually sits inside the housing just to the right of that metal "lip". It'll seep out onto that lip and down right onto the exhaust. After driving the car for a while when I got home and parked in the garage I would smell diff fluid.
It didn't take long to figure out where it was coming from.
If that is what's leaking my advice would be to take it to a reputable shop and have it fixed. You need a special tool to properly seat the new seal.

 

[BlackNBlue95]

I guess the reason the one pic that showed the front of the diff must have been dry because it was cleaned.. probably is the front seal on the diff.. let us know what you find out on that one..

 

[vms4evr]

Ok thanks for the pic vetten94. I'll wipe everything down and drive the car a bit then check that area and take a close up pic like you did. I think I missed that spot.
I may have overcleaned some areas Rick and threw you off the right track. Now I have it mostly cleaned up I'll just finish wiping everything down and then drive the car for a couple of days and check that area very carefully.
Thanks again folks. I'll keep everyone posted. It looks like rain for the next couple of days so I may not get to this until later this week.
If it is the seal I won't mess with it myself. I'll get someone who knows what they are doing.
Does this just entail removing the drive shaft to fix? Please don't tell me the whole a$$ end comes apart and the gears have to come out to get at it...
Thanks, Graham

 

[vettn94]

Does this just entail removing the drive shaft to fix? Please don't tell me the whole a$$ end comes apart and the gears have to come out to get at it...
Thanks, Graham

The exhaust will have to come down and the driveshaft will have to be removed from the rear yoke, it doesn't have to be completely removed the other end can stay in the trans just let it "hang" out of the way. The yoke needs to be removed. Like I said the seal sits just inside the front of the rear housing behind the yoke.
Taking the car to a shop is probably a good idea, it's going to be an easier job with the car on a lift but mainly because you need a special tool to properly seat the new seal. It shouldn't take more than an hour or so start to finish, that includes dropping the exhaust. I think the seal itself was only a few bucks but if you need a new pinion yoke like I did the part will run around $50.
Next time you drive the car when you get back park it and stick your nose down by the rear wheels, if that's what is leaking it should be dripping on your exhaust and you'll smell it. If you're not familiar with the smell of gear oil go grab a quart from the parts store. The only smell I hate more is trans fluid.

good luck

 

[vms4evr]

Ok. I can live with that. Just can't afford to have the rear end apart right now. An hour labor and new seal is no biggie.
When the guy installed the 3.54 gears I did buy the Master Install kit which came with a hadnful of new parts and seals. Not sure if that was part of it or not. I got the gears done back in March so it has been running fine until about 2 weeks ago. Then I noticed the smell. Gear fluid smells nasty just getting near the bottle. I think I now know what it smells like burnt. If it could possibly be worse smelling burnt...
Graham

 

[vms4evr]

Just an update. It is rear gear fluid that is leaking. It is a very tiny amount that leaks. I didn't have time to work on it this weekend but will get under the car this coming week and just double-check how tight the cover is and torque it down. It hasn't been retorqued since we did the gear swap in March so if I'm lucky it's just a little loose. If not the pinion gear seal appears to be the culprit.
Graham