Originally Posted by Uk lexi
Ii am uk based and have owned a FR lexington since 2007
It's a e450 super duty with a V10 6.8 triton
Having problems with the braking system
Having lost a lot of brake fluid and not finding any signs as to where it has gone. everywhere is dry from the brake pedal to the rotors, pipes etc no signs
I have depleted the vacuum system and the brake pedal is staying hard. is it possible for the brake assist ( servo ) to be passing fluid if so where would it go. ?? And what short term damage would it cause
Any help would be greatly appreciated
When brake fluid disappears with no visible signs it is usually a leak in the master cylinder where it joins the vacuum booster.
Two ways to diagnose. The hard way is to remove the master cylinder and look at it's rear where operating rod sticks out.
Another is far easier. Take a sheet of newsprint and roll it into a long, tight piece about the size of a long thick pipe cleaner.
Once you have this done remove the vacuum check valve on the booster can. It is the fitting where vacuum hose is attached and almost all check valves have a barbed tube that is pushed into a rubber grommet. With the check valve out use the tightly rolled newsprint as if it was a dipstick and probe ihe inside of the booster can's lower regions.
There should be NO brake fluid in this can and if the end of the newsprint comes out wet, master cylinder needs replacement.
Newsprint is preferred over regular paper as it will suck up liquids immediately and there will be no question if it's wet.
Good luck but based on your description that's the only place left for the fluid to go.
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