So, I drove the truck to work the other day and all was good. I Had to run up the road to get some things after I got home, and on the short drive the Parking brake light and the ABS light were both lit up. Brakes felt fine and no leaks noted.


Got back home and checked again for leaks, none found. Pumped the brakes and everything felt solid. Master appeared a bit low, but not unusual seeing as the brakes are probably at 50%.


Went to top it up today, and the truck was in the full sun.... when I noticed this;





Looks a bit odd? Are there 4 "Chambers" within the master? I topped it up and couldn't see a change. Rocked the truck back and forth and I only see fluid sloshing around in the outer 2 "chambers".


I've never really dealt with these specific masters and was a bit confused.


There's a white float inside the master that doesn't seem to come out so I couldn't physically see what is going on in there...


Any enlightenment would be appreciated, as my Haynes manual is no help.

 

I popped the hood on my 1995 bronco and 1997 F350. They both have similar "chambers " but i didn't notice an obvious different level of fluid

 

That is more what I would expect to see! Im pretty sure that's the way it looked before...

 

Well I have to ask..Do you have 2 or 4 lines coming off the MC? If you have 4 then it's pretty obvious.

 

Just the 2....

 

Well I've spent about 1 hours doing searches on the Ford master cylinder with NOT a great amount of luck, but I did watch a couple of videos on bench bleeding and other stuff. Watching the reverse bleeding, I noticed that even though he was bleeding the rear brake line the whole cylinder was filling evenly. You could clearly see it was a 4 baffle cylinder also, so I can only assume at this point maybe the baffles are to keep the fluid from sloshing back and forth, kind of like in a tanker truck. I can also assume if either the front or rear brakes get a leak, the whole reservoir drains out and not just one half. If this is all true and by the looks of the fluid color in your reservoir, maybe you should think about buying an aftermarket 2 chamber cylinder for more reliable braking and safety.

 

Thanks for looking into it. I had done the same and didn't really find any info.


Does anyone know if/how the float mechanism comes out? I looks like it has two little tangs that keep it in there and from floating too high/coming out? I don't wanna bugger anything up, but it would be nice to get it out so I can see what's going on in there. (Whether its just odd staining/deposits, or whether the fliud level IS wonky)


Sorry for the late reply!

 

I use a turkey baster syringe to suck as much old fluid out, then add fresh fluid. Then I start bleeding the brakes. Starting from the passenger rear, driver rear, RABS module (If so equipped), passenger front, driver front. I usually do 5 bleeds per caliper. After that, I observe and top off if necessary.

Once I have done the entire routine once, I use the baster to sort of shake and agitate the fluid in the reservoir. This helps to break up sludge and varnish.

It seems counter-productive, but I know that if you have old fluid that hasn't been changed in many years, then bleeding can cause problems by using the pumping process, since there is wear in the bore. You go to far and its not worn were the piston travels, it can start causing leakage inside the bore. Gravity or vacuum pump bleeding is usually a better idea.

 

And that's why I have the habit of exercising my brakes every once in a while when stopped at a light. I'll just mash the pedal down hard to exercise all the components to their travel limits and this also tests the brake lines and other hydraulic system parts... if I do blow something I'm already stopped!

I did blow a brake cylinder (wheel cylinder) doing this one time... I forget what vehicle it was but it's much better to find out at that point rather than while you're trying to avoid creaming the idiot in a Prius that pulled out in front of you despite their not being any traffic behind you for the next 1/4 mile or more.

OP, I wonder if there ARE partitions in there but they are open towards the top so that when the reservoir is mostly full they share fluid? Anyone got a spare they want to cut open? I'll be buying a new master soon... nothing wrong with mine but they are cheap and I like to replace them when I replace the brake booster because if it leaks then the brake fluid gets into the booster and wrecks the seals. At least on a vacuum booster it does... not sure about my hydro unit but I don't want to find out. If my new MC comes with a reservoir then I'll open up the old one and we'll see for sure what the deal is.