master cylinder leak .maybe??

[blackbomber]

Hey guys.  uh  I have had a leak where the master brake cylinder mounts to the big round black drum. My guess is that is a air vacuum container that forces air into the master cylinder???  anyway. when i topped off the brake reservior a few months ago, seems like the leak got worse because the reservior got lower than before.  so, anyway, today i cleaned up around where the m cylinder hooks to the drum and siliconed around there.  what do you think is going on with the brakes?? brakes dont feel any different...

[datzenmike]

It's actually wet??? That's not right and is a fault in the master cylinder seals. Silicone is not fixing it, it should be dry. Replace the master.

 

The brake booster is actually 'full' of intake manifold vacuum. There is a diaphragm separating the front from the rear and both contain the same vacuum. When you step on the brake, air leaks into the rear chamber and this pushes the diaphragm forward. The master cylinder is mechanically connected to the diaphragm and this applies the brakes. The vacuum assist will increase the applied pedal pressure by about 50% which reduces driver fatigue in traffic.

 

 

 

 

 

 

 

 

 

[bottomwatcher]

Hopefully no brake fluid in booster. It causes the diaphragm to rupture.

[NC85ST]

2 hours ago, bottomwatcher said:

Hopefully no brake fluid in booster. It causes the diaphragm to rupture.

Yep, had that happen. Then you have to find another brake booster, thankfully I have a parts truck.

[datzenmike]

Well change the master and booster as a single unit then. Hang onto the old master as a core or rebuildable core.

[Stoffregen Motorsports]

Have the booster rebuilt by someone like Power Brake Sales in Sacramento. The cost is about $120 and their turnaround time is a couple days.