Corrosion on Brake Booster

[ptf18]

Have a '02 Ranger Edge. Had the Driver side fender liner out while changing the O2 sensor. Looked up and saw this on the Brake booster. The corrosion starts from the master cylinder to booster joint. Brakes apparently work fine.

Any idea what is causing this corrosion?

ptf18

 

[974X4BLACKSPORT]

Brake fluid works great at stripping paint, when a master cylinder leaks from the seals it usually runs down the booster and take off the paint. It looks like at one time the master cylinder had to be changed because of leaking. It is dry now so doesn't seem to be a problem.

 

[ptf18]

974x4black. Thanks. I've own the Edge since new and have not had to do any Master Cylinder/Booster work. I'm REAL careful when changing the fluid because as you mention the fluid is a great paint stripper.

My "concern" is that I've got some type of internal leak that I don't see. I am NOT noting a drop in fluid level.

Any ideas? I'm going to touch up the corrosion but if there is a possible problem now that I have good access to the master cylinder/Booster would be the time to change it.