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Jerry Newton
Jerry Newton, Chevy Technician
Category: Chevy
Satisfied Customers: 4757
Experience:  ASE Master Technician, L1, Master GM Technician. Over 20 years of bumper to bumper GM experience.
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Trying to diagnose a problem with my front brakes,the large

Customer Question

trying to diagnose a problem with my front brakes,the large portion of my master cylinder reservior was almost empty, but can't find any traces of leakage.
Submitted: 2 years ago.
Category: Chevy
Expert:  Jerry Newton replied 2 years ago.

That brake fluid went somewhere. You've removed the drums and looked at the wheel cylinders? Any leakage at the booster? You'd see wetness just below the master cylinder, it usually makes the paint peel off the booster.

When is the last time you checked the brake fluid? Brake linings in good condition?

Customer: replied 2 years ago.
removed the drums and replaces the left rear wheel cylinder, as some former leakage was found, and I then bleed the brakes. No leakage at booster or master cylinder, I checked the fluid on Tuesday of this week and both the front(large) and back(small) reserviors were at the full mark. The brake linings are in fair condition with minor rust.
Expert:  Jerry Newton replied 2 years ago.

That fluid had to go somewhere, so if you're not seeing it on the brake lines anywhere, it has to be leaking at the master. It can also leak into the booster, which means the booster will fail soon as the brake fluid eats the rubber diaphragm.

There is no wetness inside the frame rail near the gas tank? It's just not possible for this brake fluid to disappear, it's going somewhere that you should be able to see.

Customer: replied 2 years ago.
That is where the problem set in, it is hard to distinguish which wetness is associate with what part, as this truck was bought second hand and therree is wetness everywhere except for the left front tire, engine bay, and right rear tire. The pedal isn't overly hard when trying to stop the vehicle and the brake booster appears to be working, since when building up pressure in the braking system with the ignition off and then starting the ignition results in a firm brake pedal.
Expert:  Jerry Newton replied 2 years ago.

I sometimes find it necessary to put my eyes on every inch of the brake lines to find the leak, it doesn't always jump right out at you. Inside the frame rail next to the gas tank is a common place.