1996 mark VIII brake fluid leak?

[num1bigguy]

I have a 1996 mark VIII that is losing brake fluid pretty regularly. I never see a spot in my driveway or where I park at work to see where it could be coming from. I've added about a pint of fluid in the last week. I know it's low because I get the brake light under the message center while turning left. Car has 115,000 miles. I have plenty of pressure. If I hold the brake it will eventually sink to the floor. It takes a 10 second hold. I've been searching for threads about this but haven't found much. Anyone have something like this happen?

 

[Right on the Mark]

Plain and simple you have to see leak on ground. Fill up master and stay in one spot and pump brakes till level drops in master.

 

[submariner638]

Sounds like you have a problem between the master cylinder and the bellows in the power assist unit. leaking bellows will provide vacuum to the back of the master cylinder, thereby burning the brake fluid. Try pulling the master cylinder from the power assist and see if you have brake fluid leaking from the master cylinder. Under normal operation, the power assist is under engine vacuum. When the brake pedal is depressed, external air is allowed behind the fellows, which aids the depression of the brake cylinder. One test for a tear in the bellows would be to run the engine to build up vacuum, turn off engine, then see how long it takes to lose vacuum at the bellows. Normally the vacuum will stay in the assist unit for an extended period of time. This should tell you if you are burning the fluid, or if there is some other area of concern.

 

[Right on the Mark]

If that happens you will see the paint on bottom of booster blistering off booster most of time.

 

[driller]

I would look at the rear drivers side forward fender well area underneath the car for a rusted brake line.

 

[num1bigguy]

Ok. I jammed the crap out of the pedal to see where it could be leaking from. Upon inspection I believe the leak is from the right rear caliper where the brake line bolts on. The wheel was holding the fluid and then it flung off when driving. I've included pics of both the suspected leak spot and the tire. Does anyone agree?

 

[num1bigguy]

I also tried to tighten that bolt. It did turn about 1/8 turn with just a 3/8 ratchet that is not long. I've had that happen once before many years ago. not a big tool. Couldn't apply much leverage. But it did turn. Thank you everyone for your opinions. Even though I DD this car I want it to last since the mileage is relatively low for the $900 I paid for the car. And yes I see the sway bar link is missing on this side.

 

[Spree]

Not brake related but...your wheels are backwards.

 

[num1bigguy]

Maybe I'll switch them when I do front brakes and bearings.

 

[Right on the Mark]

Clean area with brake clean so you can see if future leaking.

 

[num1bigguy]

Still no leaking at the right rear brake. Scratching my head to come up with the answer. So I decided to see if the master was leaking and filling the booster. Lo an behold, it's dry as a bone in there. Found a line leak on the drivers side by smashing the brake pedal at least 100 times. That's the leak I'm having. New possible issue. The master didn't seal back right to the booster. When car is running there is a hissing noise from the booster area. And the brakes suck. Have to push them really hard to get a little. I figured the booster doesn't need bled as it will just get its vacuum from the engine. The brakes act like there is no power assist.

 

[Bangster]

when you were smashing the brake pedal to find the leak, was the engine running?

I wore out a brake booster in my 89 Cougar bleeding the brakes with the engine off. It likely would have eventually failed, but its demise was hastened by pumping it a bunch of times after a soft line let go.

 

[num1bigguy]

Engine was running more than not during smashing.