My '87 GXL developed a very slow brake fluid leak last month. I've think I've finally tracked it down. There seems to be fluid leaking down the power brake booster where the master cylinder meets with it. I took photos but had no time to upload them before I had to go to work today. I'll upload them tonight when I get home. Do you guys think that I will have to replace the master cylinder, the brake booster, both, or just reinstall the master cylinder to the booster?

 

master is dead rebuild/replace booster should be fine.

 

If you see brake fluid leaking near the booster, it means the seals for the piston rod in the master cylinder is bad, and its leaking into the booster.

The booster is fine, just replace the master cylinder. if you have to press on the brake pedal harder to brake, then the booster is bad. If the braking pressure to apply is normal then the booster is fine.

 

I figured I would have to replace the master cylinder, wasn't sure about the booster. Thanks.