Pressurized Differential?
Thread Starter
Racer
Joined: May 2003
Posts: 439
Likes: 1
From: Palm Desert CA
Pressurized Differential?
Have a small seap leak from the driver's side of the differential, mostlikely at the outer seal. Anyway, I understand this is normal for the C5 generation vettes. I have been monitoring the differential fluid level periodically and each time I unscrew the differential fill plug I hear a release of pressure. This happens even after the car has set for a couple of days. I thought the differential had a pressure relief valve/flap????? Is this normal or should I be looking for a plugged relief valve?
Thanks
Danny
Yes, I searched, but with no answers found.
Thanks
Danny
Yes, I searched, but with no answers found.
Burning Brakes
Joined: Apr 2005
Posts: 1,123
Likes: 14
From: Booker Texas
Advanced
Joined: Feb 2005
Posts: 74
Likes: 1
differential
Before you spend a lot of money on a new seal, why don’t you try this? Jack up the back of the car put it on stands, craw under and reach up on top of the differential on the drivers side. There is a vent up there. Feels like a little pipe about ½ inch long standing straight up. See if it feels oily around it. If it does the oil might be coming from the vent. If it’s oily get an arousal can of engine degreaser and spray all over the differential and rinse it off with a garden hose with a good nozzle. After it’s clean get the car level and open the fill plug and adjust the oil level so it is 1/8”to ¼” below the fill hole. Watch it for a few days and see if you still have a leak. The sound you are hearing may be a sucking sound. I think the vent has a check valve in it to keep anything from sucking in.
Melting Slicks
Joined: Jan 2001
Posts: 2,635
Likes: 2
From: Aloha, Oregon
Just what Muller said. However, if you find you are continuously adding fluid, then you have a bona fide leak from that output shaft seal. Very common, easy to replace (relatively speaking, of course). If you have positive pressure releasing when you pop the fill port off the back then that vent cap on top might be smashed/damaged. You will want to fix that.
Robert
www.gen3motorsports.com
Robert
www.gen3motorsports.com
Racer
Joined: Oct 2005
Posts: 351
Likes: 0
From: Haw River North Carolina
Most definitely sounds like your vent is plugged. It is there because the heat generated during driving causes gas expansion which can force fluid out when the rear end becomes pressurized. I'd check / clean the vent tube before working on the seals. If its still plugged, it'll still force fluid through a seal or some other weak spot. Your leak may go away once the vent is cleared. Good Luck. Let us know what fixes it! 
Drifting
Joined: Oct 2004
Posts: 1,384
Likes: 8
From: Southwest Virginia
The rear diff vents on these cars are actually check valves. They let air out of the case but not back in. When you remove the plug you should here the air going into the case, not out, this is normal. If you remove the drain plug you can actually hear the air gurgle up through the oil.
I wouldn't call the rear diff leaks normal. It's not normal for anything to leak. I would call it common! Way too common!
I wouldn't call the rear diff leaks normal. It's not normal for anything to leak. I would call it common! Way too common!
Thread Starter
Racer
Joined: May 2003
Posts: 439
Likes: 1
From: Palm Desert CA
Nothing is Simple
Thanks for the information guys. Nothing is very simple, I guess. My leak is on the driver's side and is very slow (seep leak). As others have said, just enough to make a small mess on the diff and put spots on the garage floor. I checked the fluid level a couple of days ago and it was about 1/8 to 1/4 below the fill lip. The sound I hear may indeed be from air being pulled into the diff rather than pushed out. I think I will attempt to clean/clear the vent and wash down the diff, then monitor for further leaking.
I can certainly live with a seep leak and monitor the fluid level at each oil change, but I wouldn't have thought that I would have to do such things on a corvette.
Danny
I can certainly live with a seep leak and monitor the fluid level at each oil change, but I wouldn't have thought that I would have to do such things on a corvette.
Danny
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Advanced
Joined: Oct 2005
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Originally Posted by SGT. PYLE
I noticed exactly the same thing today wile changeing my diff. fluid. I am going to check that pressure relief valve but how can I tell if it is clogged or not?
The negative pressure has much less of a chance of causing a seal leak than a positive pressure, as a vacuum would tend to draw the seal closer to the shafts. I wouldnt worry about a vacuum unless it is significant.
