A leak between Master Cylinder & Booster

Messages
59
Location
USA
Hello, Quite confused though, I noticed Brake light is on at all times in instrument panel cluster. I checked brake reservoir is completely empty.And then I noticed there is a leak between Master Cylinder & Brake Booster. I tightened the 2 bolts holding the Master Cylinder to the Booster and drove it a mile and there is still leaking. The brakes seems normal though. May I ask which one is the culprit between the 2? BTW the vehicle is a 1984 Isuzu P'up truck
 
Last edited:
Messages
1,136
Location
PA
The seal that surrounds the rod that the booster presses on is likely going bad. I had this is my Odyssey and replaced it. Check RockAuto for a replacement. I think I spent $60.
 
Messages
3,253
Location
USA
Master cylinder piston seal is bad and / or the bore is worn. Replace the master cylinder. The seal on the booster side has nothing to do with this. There is an intentional gap between the cylinder and the booster so that brake fluid from a leaky cylinder will run out the gap rather than getting inside the booster to damage it. The rubber parts inside the booster are not compatible with brake fluid. Some earlier designs did not have a gap, and then a leak in the master cylinder also meant the booster would fail.
 
Top