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Rear brake fluid lead

bwing

Well-known member
Joined
Oct 28, 2005
Messages
517
Location
California
Corvette
03 Z06,66 coupe(sold),99 Porsche Carrera(sold)
I'm experiencing a very minute brake fluid leak coming from the rear of the car after it has been driven for about 1 1/2 hrs and is parked on fairly level ground. It doesn't do this all the time, only when I park the car on my mother-in-laws driveway. (I know I'm going to get some really good responses to this one.) It doesn't do this at any other times. Is there an overflow valve for brake fluid at the rear of the car just left of center almost between the rear tire and rearend. I've looked for leakage and found nothing.
 

zagger

Well-known member
Joined
Apr 22, 2006
Messages
468
Location
San Diego
Corvette
99 C5 Convertible
Just a wild shot but where is the leek exactly. If it is in the center of rear it might be the rear seal in the transmission, I'm assuming it is a 6 speed. There is a weep hole between trany and the dif. just for that purpose. I'm not aware of any overflow in any brake system, even ABS. Or it might be just en excuse not to visit mother in law. Wish I would have thought of that one ;).
 

bwing

Well-known member
Joined
Oct 28, 2005
Messages
517
Location
California
Corvette
03 Z06,66 coupe(sold),99 Porsche Carrera(sold)
Just a wild shot but where is the leek exactly. If it is in the center of rear it might be the rear seal in the transmission, I'm assuming it is a 6 speed. There is a weep hole between trany and the dif. just for that purpose. I'm not aware of any overflow in any brake system, even ABS. Or it might be just en excuse not to visit mother in law. Wish I would have thought of that one ;).

The leak is about just left of the trans and the fluid is clear, very thin liquid. I'm guessing that it's about 1/8th of a tsp that drips and probably not much more than that. Although I've never messed with the trans fluid, I'm assuming that it's a thicker liquid than the brake fluid. I've worked on older vehicles and the weight of the gear fluid for rear ends back in the day was close to a 90 wt. This stuff is much thinner in viscosity. I'll look for the weep hole to see if there is any buildup of fluid around it. Thanks alot.
 
1

1stiff84

Guest
Are you sure it is brake fluid, and not axle lube from the diff?
 

zagger

Well-known member
Joined
Apr 22, 2006
Messages
468
Location
San Diego
Corvette
99 C5 Convertible
Both the diff. and trans would be very hot after 1 1/2 hour drive. Heat causes both fluids to become very liquidly ( very scientific description :) ). Between the heat and pressure the oil that seeps past the seals would be close in appearance to brake fluid. Hope that is not the case tho because that could be a pricey repair. Best of luck and keep us posted on what you find. Regards, Zig.
 

gmjunkie

Well-known member
Joined
Nov 11, 2004
Messages
4,547
Location
Old Fort NC/Vero Beach FL
Corvette
03 Z-51,78 L82 Coupe
The leak is about just left of the trans and the fluid is clear, very thin liquid. I'm guessing that it's about 1/8th of a tsp that drips and probably not much more than that. Although I've never messed with the trans fluid, I'm assuming that it's a thicker liquid than the brake fluid. I've worked on older vehicles and the weight of the gear fluid for rear ends back in the day was close to a 90 wt. This stuff is much thinner in viscosity. I'll look for the weep hole to see if there is any buildup of fluid around it. Thanks alot.
On the left side clear up at the floor above the transmission there are 2 Brake lines with splicer fittings!!! One or both need to be tightened!! I've seen it a couple times!!!:upthumbs PS.The differential fluid is kinda thin and looks like brake fluid too,and the vent is right on top left!!
 

bwing

Well-known member
Joined
Oct 28, 2005
Messages
517
Location
California
Corvette
03 Z06,66 coupe(sold),99 Porsche Carrera(sold)
Both the diff. and trans would be very hot after 1 1/2 hour drive. Heat causes both fluids to become very liquidly ( very scientific description :) ). Between the heat and pressure the oil that seeps past the seals would be close in appearance to brake fluid. Hope that is not the case tho because that could be a pricey repair. Best of luck and keep us posted on what you find. Regards, Zig.

Thanks Zig, I'll check it out. And just so we're both in the same boat....liquidly sounds ok to me. :beer
 

bwing

Well-known member
Joined
Oct 28, 2005
Messages
517
Location
California
Corvette
03 Z06,66 coupe(sold),99 Porsche Carrera(sold)
On the left side clear up at the floor above the transmission there are 2 Brake lines with splicer fittings!!! One or both need to be tightened!! I've seen it a couple times!!!:upthumbs PS.The differential fluid is kinda thin and looks like brake fluid too,and the vent is right on top left!!

I'll be under the car on Friday morning. I'll let you and Zig know what I find. I drove the car today around town, got home, parked it on the driveway and no leak. It's puzzling. If it only happens when I visit my mother-in-law I'll have to start spacing my visits. ;LOL
 

bwing

Well-known member
Joined
Oct 28, 2005
Messages
517
Location
California
Corvette
03 Z06,66 coupe(sold),99 Porsche Carrera(sold)
I checked the trans and diff for that weep hole and couldn't find any sign of a leak. Also checked tightness of brake lines and they appeared ok. No signs of leakage around any of the boots. Thanks again for the advice and if I do discover what's causing it I'll be sure to post in case anyone else has the same problem.
 
1

1stiff84

Guest
Maybe it's just your mother-in-law messin' with ya?

Check the driver's side cover on the rear axle case for an oil leak.
 

bwing

Well-known member
Joined
Oct 28, 2005
Messages
517
Location
California
Corvette
03 Z06,66 coupe(sold),99 Porsche Carrera(sold)
Maybe it's just your mother-in-law messin' with ya?

Check the driver's side cover on the rear axle case for an oil leak.

I checked the entire rear end and couldn't find any sign of leakage. Everything underneath was dry. Maybe you're right, it just could be my m-i-l messing around. ;LOL
 

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