| Missing brake fluid [message #272513] |
Mon, 23 February 2015 18:49  |
kerry pinkerton
Messages: 2565
Registered: July 2012
Location: Harvest, Al
Karma: 15
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Senior Member |
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Sunday, I drove down to Ken Henderson's to do some pit projects. On the way, my brake pedal felt really low and when I checked the fluid the front reservoir (rear brakes) was down an inch. Brakes were really marginal the rest of the trip but would pump up and stop OK.
Today we got it on the rack and could find NO EVIDENCE of any leaks. NONE!
So we started thinking about where the fluid could have gone. Master cylinder leaking into the booster was about all we could come up with. Replaced the MC and pressure bled the brakes with Ken's Hupy bleeder, got a good bit of air out of the lines, especially the right rears.
Pedal feels OK now but I haven't driven it yet.
So here is the question for the brain trust. Where did the fluid go and how did the air get in the system when there are no leaks?
Just to set the stage. The MC is an original, Lenzi Sensitized booster, Manny Brakes on the rear and Manny 1 ton on the front. Combination valve was modified to remove the delay by Ken when we put the Manny Brakes on a couple years back.
Ken and I are scratching our heads on this one? Thoughts?????
Kerry Pinkerton - North Alabama
Had 5 over the years. Currently have a '06 Fleetwood Discovery 39L
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| Re: Missing brake fluid [message #272519 is a reply to message #272513] |
Mon, 23 February 2015 20:22  |
kerry pinkerton
Messages: 2565
Registered: July 2012
Location: Harvest, Al
Karma: 15
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Senior Member |
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Matt, that was our first thought also but the back of the master cylinder was DRY AS A BONE! I've changed the MC but could easily do an oil change before I start home.
Kerry Pinkerton - North Alabama
Had 5 over the years. Currently have a '06 Fleetwood Discovery 39L
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| Re: Missing brake fluid [message #272558 is a reply to message #272513] |
Tue, 24 February 2015 11:55 |
Steve
Messages: 506
Registered: September 2013
Location: East Greenville, Pa
Karma: 1
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I had a leak that dripped on top of the front frame and ran into a hole in the frame and accumulated in the boxed frame so nothing was hitting the ground. It took me a while to figure out.
1978 GMC Royal
Eastern Pennslyvania
1968 Chevrolet C20 396 Camper Special
1969 Chevrolet C20 Camper Special
1985 Buick Electra Park Avenue
1992 Camaro 25th Anniversary Heretage Edition Black
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| Re: Missing brake fluid [message #272582 is a reply to message #272513] |
Tue, 24 February 2015 19:55 |
kerry pinkerton
Messages: 2565
Registered: July 2012
Location: Harvest, Al
Karma: 15
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Senior Member |
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Mystery solved. Larry Davick posted about pad wear making the fluid go down. Makes sense so this morning first thing, I pulled the wheels off again and took a look. To my absolute shock and amazement, BOTH the caliper bolts were MISSING on the right rear caliper. Just frigging GONE!
The outside of the caliper and the inside of the Alcoa were worn where they had been rubbing on each other. The Alcoa had a bit of wear but not enough to worry about. There was also wear on the inside of the caliper where it was rubbing on the rotor. About this time Ken came out and joined in the amazement. Obviously, when he or I installed the Manny brakes back in '13 we never tightened the bolts and they just worked themselves out. That is the only explanation I can think of. All three other calipers are nice and tight.
What we think happened is that the friction caused by the rubbing boiled off the fluid or the seal was damaged by the beating around. It was damaged a good bit although we saw no sign of leakage, we're thinking it was pushing fluid and sucking air. The heat may have caused the leak not to be visible.
The rotor was pretty ugly where the caliper had been bouncing around on it and the shoes were shot. Fortunately, our friend (and engine builder) JOhn Beavers, had his box of Manny Brake components not yet installed and graciously gave me the parts I needed. I'll have Manny send him replacements.
Just to keep things in balance, I'm replacing both rear calipers, rotors, and pads.
The funny thing is that both Ken and I had our hands on the caliper yesterday and never noticed the problem.   
Kerry Pinkerton - North Alabama
Had 5 over the years. Currently have a '06 Fleetwood Discovery 39L
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| Re: [GMCnet] Missing brake fluid [message #272590 is a reply to message #272582] |
Tue, 24 February 2015 23:00 |
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USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
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Senior Member |
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Kerry,
Thanks for sharing the goof! It's nice to learn from OPM's (Other People's Mistakes) rather than my own!
It's comforting to know others do the same kind of things I do!
Don't know about you but it seems with me the frequency of occurrences is directly proportional to my age.
Regards,
Rob
-----Original Message-----
From: Kerry Pinkerton
Mystery solved. Larry Davick posted about pad wear making the fluid go down. Makes sense so this morning first thing, I pulled the
wheels off again and took a look. To my absolute shock and amazement, BOTH the caliper bolts were MISSING on the right rear
caliper. Just frigging GONE!
The outside of the caliper and the inside of the Alcoa were worn where they had been rubbing on each other. The Alcoa had a bit of
wear but not enough to worry about. There was also wear on the inside of the caliper where it was rubbing on the rotor. About this
time Ken came out and joined in the amazement. Obviously, when he or I installed the Manny brakes back in '13 we never tightened
the bolts and they just worked themselves out. That is the only explanation I can think of. All three other calipers are nice and
tight.
What we think happened is that the friction caused by the rubbing boiled off the fluid or the seal was damaged by the beating
around. It was damaged a good bit although we saw no sign of leakage, we're thinking it was pushing fluid and sucking air. The heat
may have caused the leak not to be visible.
The rotor was pretty ugly where the caliper had been bouncing around on it and the shoes were shot. Fortunately, our friend (and
engine builder) John Beavers, had his box of Manny Brake components not yet installed and graciously gave me the parts I needed.
I'll have Manny send him replacements.
Just to keep things in balance, I'm replacing both rear calipers, rotors, and pads.
The funny thing is that both Ken and I had our hands on the caliper yesterday and never noticed the problem. 8o 8o :blush: :lol:
--
Kerry
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Regards,
Rob M. (USAussie)
The Pedantic Mechanic
Sydney, Australia
'75 Avion - AUS - The Blue Streak TZE365V100428
'75 Avion - USA - Double Trouble TZE365V100426
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