Brake fluid leaking from pressure switch
06-03-2018, 09:36 PM
#1
Instructor
Thread Starter
Brake fluid leaking from pressure switch
Been trying to find the source of my soft brake pedal on my '85 and I think I may be homing in on it.
Soft pedal started when I installed a DRM bias spring in the master cylinder. M/C was pretty old, possibly original so I thought maybe the seals were just worn out. So I got a new one. Put the DRM spring in it. Pedal still goes to the floor.
Today I was fooling around with it and noticed a little fluid spurting out of the pressure switch when I push the pedal (wire disconnected). Seems to me there shouldn't even be fluid in that part.
Also odd (to me) is that fluid flows from the bleeder screws without pushing the pedal.
I'm guessing I screwed up something when installing the spring, but not sure what.
I've done master cylinder replacements beforebefore, but the integral proportioning valve kinda complicates things.
Soft pedal started when I installed a DRM bias spring in the master cylinder. M/C was pretty old, possibly original so I thought maybe the seals were just worn out. So I got a new one. Put the DRM spring in it. Pedal still goes to the floor.
Today I was fooling around with it and noticed a little fluid spurting out of the pressure switch when I push the pedal (wire disconnected). Seems to me there shouldn't even be fluid in that part.
Also odd (to me) is that fluid flows from the bleeder screws without pushing the pedal.
I'm guessing I screwed up something when installing the spring, but not sure what.
I've done master cylinder replacements beforebefore, but the integral proportioning valve kinda complicates things.
06-04-2018, 10:30 AM
#2
Race Director
You are right, the pressure switch should not have any contact with brake fluid. Unfortunately it sounds like the master cylinder is shot.
06-04-2018, 10:56 AM
#3
Instructor
Thread Starter
Supposedly a new m/c. I figure I jacked something up putting the spring in, just can't figure what.
Maybe I'll just run it over to DRM and let them put the spring in.
Maybe I'll just run it over to DRM and let them put the spring in.
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yakmastermax (12-28-2023)
06-13-2018, 11:10 PM
#4
Instructor
Thread Starter
Got it working, although I'm not totally sure what was wrong.
My suspicion was that either the combination piston wasn't in the right place or I got too much air in it when I moved it from bench bleeding to the car (I couldn't find plugs that would fit the ports).
So I removed the comb piston and reinstalled it, making sure it was seated all the way to the back of the cylinder. the last inch took A LOT of pressure with a screwdriver but it finally thunked solidly into place.
I then jacked the rear to get the m/c level and bled the m/c on the car, then went around and bled the wheel cylinders in order.
Battery is currently dead so I haven't gone for a test drive yet but pedal feels nice and firm.
My suspicion was that either the combination piston wasn't in the right place or I got too much air in it when I moved it from bench bleeding to the car (I couldn't find plugs that would fit the ports).
So I removed the comb piston and reinstalled it, making sure it was seated all the way to the back of the cylinder. the last inch took A LOT of pressure with a screwdriver but it finally thunked solidly into place.
I then jacked the rear to get the m/c level and bled the m/c on the car, then went around and bled the wheel cylinders in order.
Battery is currently dead so I haven't gone for a test drive yet but pedal feels nice and firm.