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I have a 69 with a 351 Clevor. A few weeks back I had some brake issues where my front reservoir was going dry and by brake pedal was to the floor. I took the car in and they said it was the master cylinder and they replaced it. That was about a month ago and I have only driven the car about 50 miles since then... Let me say right here I would normally do it myself but I am waiting for back surgery so bending over right now is **** painful... Anyway...I Was driving today and the pedal went soft and then right to the floor. Got the car home, popped off the top of the MC and the front reservoir is dry and the back was spilling over full. So I removed some from the back reservoir, filled up the front and drove around the block. Pulled off the top of the MC and same thing...front empty, back over flowing... WTF !!!
So my question is, has anyone had this issue ? Is it a bad MC ? I have no fluid in the drivers side of the car so it's not leaking into the cabin. Any help would be greatly appreciated !
I have a 69 with a 351 Clevor. A few weeks back I had some brake issues where my front reservoir was going dry and by brake pedal was to the floor. I took the car in and they said it was the master cylinder and they replaced it. That was about a month ago and I have only driven the car about 50 miles since then... Let me say right here I would normally do it myself but I am waiting for back surgery so bending over right now is **** painful... Anyway...I Was driving today and the pedal went soft and then right to the floor. Got the car home, popped off the top of the MC and the front reservoir is dry and the back was spilling over full. So I removed some from the back reservoir, filled up the front and drove around the block. Pulled off the top of the MC and same thing...front empty, back over flowing... WTF !!!
So my question is, has anyone had this issue ? Is it a bad MC ? I have no fluid in the drivers side of the car so it's not leaking into the cabin. Any help would be greatly appreciated !
Fluid Transfer would be a Master Cylinder Issue IIRC. I Was Brake Certified in Get This 1981! So Memory is Not The Best. Try & Get New if Possible. The Cores on a Vehicle of that Vintage Are Likely Getting To Be Pretty Poor Quality on the Remans. New Parts Don't Always Work Correctly Either. Is It Power, Manual, Front Disc or Drum All Around. If You Let Me Know Perhaps I Can Find The Highest Quality One For You. Can You Also Give Me Part Number an Manufacturer of Cylinder You Had Installed??? I'm Assuming Stock Brakes????
Fluid Transfer would be a Master Cylinder Issue IIRC. I Was Brake Certified in Get This 1981! So Memory is Not The Best. Try & Get New if Possible. The Cores on a Vehicle of that Vintage Are Likely Getting To Be Pretty Poor Quality on the Remans. New Parts Don't Always Work Correctly Either. Is It Power, Manual, Front Disc or Drum All Around. If You Let Me Know Perhaps I Can Find The Highest Quality One For You. Can You Also Give Me Part Number an Manufacturer of Cylinder You Had Installed??? I'm Assuming Stock Brakes????
KC
Thanks for the quick reply. Front disc rear drum power brakes. The heads are off of a 71 351C 2V... Didn't have the $$$ at the time of build to buy aluminum heads... What is IIRC ?... Back in 81 I was working in a body shop sanding cars before I got my painters ticket. So I hear ya about the old memory !
Thanks for the quick reply. Front disc rear drum power brakes. The heads are off of a 71 351C 2V... Didn't have the $$$ at the time of build to buy aluminum heads... What is IIRC ?... Back in 81 I was working in a body shop sanding cars before I got my painters ticket. So I hear ya about the old memory !
Thanks
I Had To Google it Myself! The Guys Were Using it on Here! {IF I Remember Correctly}! Let Me Check on What's Out there as Far as M/C's !
I'm Liking These Raybestos Listed at Rock Auto. You Should Be Able To Get Raybestos Locally I Would Think Also! The Port Size has to Be Checked to get Correct One! Just FYI's From Me!
,
RAYBESTOS MC36226 Specifications Bore Size (IN) 1.000 Master Cylinder Material Iron Mounting Hole Diameter (IN) 0.394 Mounting Hole Quantity 2 Port Quantity 2
Primary Port Thread A 1/2"-20
Secondary Port Thread A 9/16"-18
RAYBESTOS MC36251 Specifications Bore Size (IN) 1.000 Master Cylinder Material Iron Mounting Hole Diameter (IN) 0.421 Mounting Hole Quantity 2 Port Quantity 2
Primary Port Thread A 3/8"-24
Secondary Port Thread A 1/2"-20
KC
Oh I Have Had Good Luck With this Brand Over The Years! Of Course Quality on Many Brands Have Gone Down Hill as Time Goes On!
Thanks very much. I hope this is the problem. I will be doing it myself this time...sore back or not !! That's what whiskey is for !
You Are Welcome!
Get Some Good Help To Bleed The System! Got To Thinking! Eyeball the Proportioning Valve as Well. If It's Got Any Seeping at the Switch it's Toast. Thankfully They are Repoping Them Now! If You Have To Fool with it Make Sure & Soak with WD-40 or Similar A Day or Two Before Attempting and Use Line Wrenches! I Don't Think its the Transfer Issue But a Good Thing To Check! Oh And Have The Whiskey After the Repair! Speaking From Past Experience!
Get Some Good Help To Bleed The System! Got To Thinking! Eyeball the Proportioning Valve as Well. If It's Got Any Seeping at the Switch it's Toast. Thankfully They are Repoping Them Now! If You Have To Fool with it Make Sure & Soak with WD-40 or Similar A Day or Two Before Attempting and Use Line Wrenches! I Don't Think its the Transfer Issue But a Good Thing To Check! Oh And Have The Whiskey After the Repair! Speaking From Past Experience!
Thanks for the tips. I replaced the prop valve last year. it had a leak...
You Are Welcome! I have Done My Share of Ford Brakes! I Got Two 67 Fords Both Power Drum 390 Cars! The LTD Stops on a Dime! The 67 Fairlane Stops Like the Queen Mary! Just Bizzare! Only Real Difference is Size of Power Brake Booster!
Well that didn't work...changed the master cylinder and it's doing the exact same thing...
Check this Out! Maybe Some Debris in the Distribution Block. Also Does Yours Have The Other Residual Check Valve Shown in Pic. {ROUND CYLINDER} Those are Rare! Anyhoo Good Reference Pics! Reading Article it Looks Like The Valves Sometimes Come With Orings Installed Incorrectly as Well!
I Have Also Had Brake Boosters Suck the Fluid Out of Master Cylinders a Time or Two. Might Check Booster For Any Signs Of Fluid Seepage.
You Did a 4 Wheel Brake Bleed ????? Not Just at Master????
Check this Out! Maybe Some Debris in the Distribution Block. Also Does Yours Have The Other Residual Check Valve Shown in Pic. {ROUND CYLINDER} Those are Rare! Anyhoo Good Reference Pics!
I Have Also Had Brake Boosters Suck the Fluid Out of Master Cylinders a Time or Two. Might Check Booster For Any Signs Of Fluid Seepage.
You Did a 4 Wheel Brake Bleed ????? Not Just at Master????
I did have a cylinder type of DB, but it was leaking and it was replaced with this... ( https://www.themustangshop.ca/product/307070/658071# )
I didn't see any evidence of fluid in the booster. Why would the fluid go from 1 reservoir to the other ??? I doubt very much that I have had 2 bad master cylinders
This is driving me crazy...a short drive I know...
I Just Realized My Shop Manual for the Daughters 67 Fairlane Should Also Pretty Much Pertain to Your car & I'm Starting to Check it Out.
According to that Link I Posted Those Valves Can Be Problematic with O-Rings Installed Incorrectly. May Have to take a look. That Round Cylinder I Believe You Should Have is the Residual Check Valve For The Front Disc. I Don't Know if It Being Bad Could Cause a Fluid Loop or Transfer.
The Fluid Has to Be Going Somewhere. Leaking in a Hard To Detect Area Etc.. I Have Had Boosters Suck Fluid and Get Pulled in to Intake From Booster Vacuum Line. Plugging Off Vacuum Line And Driving Around Block With a Hard Pedal Would Show if it Was The Issue if No Fluid Was Lost! Ez Test!
Are you Thinking it is All Spilling Over and Out into Engine Compartment??
Did You Do a 4 Wheel Bleed and If So Did They Bleed Oddly in Any Way? R/R, L/R, R/F and Left Front Bleed? If Not Aware That is Bleed Sequence.
Here is a Long Shot I Have Ran into on my 67 Ltd See That Metal Piece That Goes Between Booster and Cylinder The Piece of Plastic Should Have Vent Slots in it On Bottom. Make Sure It Was Not Silicone Sealed Up at Some Point It Will Cause Fluid Sucking Issues. It's Been a Lot of Years Since I fooled With That Car So Bear With Me. Its Foggy Memories! It Will Be Brittle as Well So be Careful! that is If Your Car Has The Same Style Booster as this Guy Which is Like My 67 Ltd
I Just Realized My Shop Manual for the Daughters 67 Fairlane Should Also Pretty Much Pertain to Your car & I'm Starting to Check it Out.
According to that Link I Posted Those Valves Can Be Problematic with O-Rings Installed Incorrectly. May Have to take a look. That Round Cylinder I Believe You Should Have is the Residual Check Valve For The Front Disc. I Don't Know if It Being Bad Could Cause a Fluid Loop or Transfer.
The Fluid Has to Be Going Somewhere. Leaking in a Hard To Detect Area Etc.. I Have Had Boosters Suck Fluid and Get Pulled in to Intake From Booster Vacuum Line. Plugging Off Vacuum Line And Driving Around Block With a Hard Pedal Would Show if it Was The Issue if No Fluid Was Lost! Ez Test!
Did You Do a 4 Wheel Bleed and If So Did They Bleed Oddly in Any Way? R/R, L/R, R/F and Left Front Bleed? If Not Aware That is Bleed Sequence.
Kc
I didn't do a bleed at the wheels. The pedal was firm and seemed fine. Drove the car a couple of miles then the pedal went soft.
So the car did not like that test!! LOL...pulled the Vac line, plugged the hole at the fitting on the booster and went around the block. Still lost fluid...sigh
I didn't do a bleed at the wheels. The pedal was firm and seemed fine. Drove the car a couple of miles then the pedal went soft.
So the car did not like that test!! LOL...pulled the Vac line, plugged the hole at the fitting on the booster and went around the block. Still lost fluid...sigh
I Would Do a 4 Wheel Bleed and See If Anything Strange happens! When The Pedal Goes South Does the Brake Warning Light Come On???
The lights not hooked up...don't judge...LOL... Odd thing is, when i looked in the MC after the 'test' there was some white contaminants in the fluid in the front reservoir. Snot like consistency...
Could the prop valve be pushing back fluid into the MC ?
The lights not hooked up...don't judge...LOL... Odd thing is, when i looked in the MC after the 'test' there was some white contaminants in the fluid in the front reservoir. Snot like consistency...
Could the prop valve be pushing back fluid into the MC ?
I Have Played With those and it takes Very Little to Stick One! They are Very Tight in Tolerances. A 4 Wheel Bleed to Flush the System would Be a Good Start and Then You May Have to Tear Prop Valve Down. If You Have Residual Round Piece I think you Can Take apart to Clean But Not Sure. Have Not Searched for One of Those Lately. If It has O-rings inside Maybe Hard to Source. Nevermind they are Repoping Them as Well!
I Got to Thinking a Snot Consistency Would Be inline With Wrong Brake Fluid Being Used or Added at some Point. Dot 5 Will Turn Dot 3 Brake Fluid to Jelly I Believe. It Would Also Eat Up Old School Brake Rubber Pieces. Could Somebody have Added Wrong Fluid. Dot 5 or Synthetic Mixed With Old School Dot 3 ??? Only Other Thought is Assembly Grease From New Cylinder.
Oh and Hook the Light Up! It Will Help with Diag in the Future!
I Would Flush System With Known Correct Fluid Get a Big Bottle and Use a Lot To Flush!
Well It's getting Late! I'm going to Crash! I will Likely Wake up at 2:00 A.M. and Have Another Idea! That's How My Noodle Works! Sleep on it Works For Me! Give it a Try!
So just an update. I did bleed all 4 wheels, and all are good. NO leaks anywhere. I pulled the drums and no leaks in the cylinders... I filled the MC and drove the car for about 2-3 miles. Got home, pulled the lid off the MC and it's still transferring fluid from the front to back chamber. I think the "leak" issue I am having is when the back chamber in the MC gets to full the pressure makes it leak past the rubber gasket.
So my question is, Can a bad proportional valve cause fluid to flow BACK into the MC ? The prop valve I currently have on the car is this one...1967-1969 Mustang Disc Brake Distribution Block | The Mustang Shop. It was put in last summer as the old one was leaking.
After Eliminating What it is Not What Is Left is the Prop Valve & Residual check Valve. A Look In side the Prop Valve For a Sticking Valve or Torn O-Ring Would Be My Next Try! The Fact That The Article I Posted Said There was Issue With O-rings Being Incorrectly installed Causes Even more Suspect.
This Kit Though Not Available Shows O-rings Very Similar But Not Quite the Same. Who Knows What Could Happen If Incorrectly Installed. Could Work Correctly For awhile & Then Have Internal Bypass.
6/24/23, 04:02 PM
