M816 brake questions

[phaux]

Background: I purchased an M816 several years ago. Right before picking it up the owner let me know the brakes didn't work, so I had it towed, where it has been sitting since. I finally got around to assembling a power bleeder yesterday and bled all the brakes. The reservoir was completely empty and the lines had air in them, especially the front two wheel. The front two wheels also seemed dirtier/greasier than the other wheels under the truck. Once bleeding was complete, the brakes work amazingly well. During the bleeding process, no visible leaks were seen.

Question: Could the dirtiness of the front wheels be attributed to some leaking brake component, if so, what should I start looking at/for? What are some reasons the reservoir was completely empty, and what/where should I be looking for issues?

 

[NDT]

Dirty front wheels can be attributed to leaky knuckles or leaky wheel cylinders.
I have found that brake fluid somehow magically disappears even with no visible leaks. In your case I would check level frequently.

 

[WillWagner]

Yup, some trucks the fluid just disappears, some not. My deuce never lost any fluid, the 5 ton I just did lost all the fluid in the MC with no leaks. Topped the cylinder off, worked the pedal and brakes were back. Didn't even need to bleed them.