diagnosing brake issue - 73 270
Posted: Fri May 10, 2019 1:02 pm
Hi folks,
I have a 73 270 with M375 chassis and dual booster setup. Last fall before I parked the rig after 1.5 years of good braking operations I had a pedal going to the floor and brake light coming on. Getting to the bottom of it now...
I pulled the master cylinder cover and found the fluid was down quite a bit. The boot was in good shape and appeared to make a tight seal. I also prior to this could not find evidence of a leak anywhere, at least easily visible. I refilled the cylinders to 1/4" from the top and put the cover back on - a bunch of fluid spilled over when this happened.
After pumping the brakes a few times (engine off) I had the original very firm brake feel. After starting it up and pumping some more it was a bit erratic with the light coming on mid stroke briefly, and getting some feedback from the pedal I wasn' t familiar with. Checked for leaks around the master cylinder but could identify none. After some time the pedal would go to the ground again, and couldn't build up the same pressure as I initially had before I turned the engine on.
Is the next step to bleed the system starting from the furthest cylinder from the master? Its possible the fluid was low enough in the cylinders that air got into the system, I can't say with certainty it didn't. I never pumped the brakes with the cover off during the refill.
Thanks all for any advice you can offer.
I have a 73 270 with M375 chassis and dual booster setup. Last fall before I parked the rig after 1.5 years of good braking operations I had a pedal going to the floor and brake light coming on. Getting to the bottom of it now...
I pulled the master cylinder cover and found the fluid was down quite a bit. The boot was in good shape and appeared to make a tight seal. I also prior to this could not find evidence of a leak anywhere, at least easily visible. I refilled the cylinders to 1/4" from the top and put the cover back on - a bunch of fluid spilled over when this happened.
After pumping the brakes a few times (engine off) I had the original very firm brake feel. After starting it up and pumping some more it was a bit erratic with the light coming on mid stroke briefly, and getting some feedback from the pedal I wasn' t familiar with. Checked for leaks around the master cylinder but could identify none. After some time the pedal would go to the ground again, and couldn't build up the same pressure as I initially had before I turned the engine on.
Is the next step to bleed the system starting from the furthest cylinder from the master? Its possible the fluid was low enough in the cylinders that air got into the system, I can't say with certainty it didn't. I never pumped the brakes with the cover off during the refill.
Thanks all for any advice you can offer.