unimog
Active member
My 2008 sprinter was leaking brake fluid requiring fill ups. There were no visual leaks anywhere. The pedal started to go down when holding at traffic lights. With engine off the pedal was hard. Engine running and applying brakes caused the pedal to drift down slowly.
Since I could find no leaks I decided to replace the MC thinking that it was leaking into the vacuum booster. Replaced the MC with one from Europarts and bled the brakes using a pressure bleeder until the calibers were flowing fluid without bubbles.
Trying the brakes without driving resulted in the same condition, a sinking pedal with engine running but hard with engine off.
Next pressurized the brake booster to 15 psi and left it like that to to see if it would hold. Amazingly it showed no reduction in pressure overnight.
Next pumped the pedal many times with the van jacked up and checked for leaks. No leaks at the calibers or brake hoses or MC. But after doing this for some time noticed some dripping from the lower part of the fuel tank and it was not diesel fuel. Turns out there is a leak in the area above the fuel tank where it is impossible to see without lowering the tank.
Called Sun Motor in Mechanicsburg PA and found out they had recently fixed a van with the same condition. The fix was to replace corroded brake tubing above the fuel tank.
This required dropping fuel tank and replacing all brake tubing in that area.
Scheduled an appointment for next week
The reason that there were no visible leak before when checking underneath I think was because the leaking fluid would disappear when driving without leaving drips when parked and when parked there were no leaks.
I will update you after the repair
There has been much discussion on here about soft brakes without obvious solutions so hopefully this will help some of you with similar problems
Since I could find no leaks I decided to replace the MC thinking that it was leaking into the vacuum booster. Replaced the MC with one from Europarts and bled the brakes using a pressure bleeder until the calibers were flowing fluid without bubbles.
Trying the brakes without driving resulted in the same condition, a sinking pedal with engine running but hard with engine off.
Next pressurized the brake booster to 15 psi and left it like that to to see if it would hold. Amazingly it showed no reduction in pressure overnight.
Next pumped the pedal many times with the van jacked up and checked for leaks. No leaks at the calibers or brake hoses or MC. But after doing this for some time noticed some dripping from the lower part of the fuel tank and it was not diesel fuel. Turns out there is a leak in the area above the fuel tank where it is impossible to see without lowering the tank.
Called Sun Motor in Mechanicsburg PA and found out they had recently fixed a van with the same condition. The fix was to replace corroded brake tubing above the fuel tank.
This required dropping fuel tank and replacing all brake tubing in that area.
Scheduled an appointment for next week
The reason that there were no visible leak before when checking underneath I think was because the leaking fluid would disappear when driving without leaving drips when parked and when parked there were no leaks.
I will update you after the repair
There has been much discussion on here about soft brakes without obvious solutions so hopefully this will help some of you with similar problems