brake fluid leak - Impala Tech
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post #1 of 8 (permalink) Old 07-29-2016, 12:57 PM Thread Starter
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Cool brake fluid leak

Hi all... Quick question. I'm not sure if this is a brake fluid leak however after sitting over night, I saw a small clear drop of oily substance under the front of my car, under the frame, where the brake line runs. I have an oil leak that's built up all sorts of sludge under my car so I wasn't able to tell just by looking at the lines. Anyway, I wasn't too concerned and drove to work - no issues. My commute home can be up to 3 hours in traffic, so I think I'd definitely know if I had a leak with all the stopping.

I'm at work right now so I can't really hose down the affected area and give it a good test, however I did pump the brakes and hold them down firmly with the car off. I also left the car running so the brake power booster would kick in and held the brake pedal down with a little force for 2 minutes - I did that about 3 times. The pedal felt normal, as it usually does, it didn't go to the floor and held it's usual stiffness. I looked under the car in the affected area and didn't see any drips (again, there's oil and sludge build up, but I can still see the brake lines - they're just covered with oily sludge/dirt). Given the fact that I drove home in traffic last night, and back to work again just fine today - on top of the brake pedal test I tried, what are the chances that I have a leak in that area (my master cylinder was filled to it's normal level).

p.s. I was a bit thrown off because, correct me if I'm wrong, a small drop of brake fluid that dripped on the cement garage floor would have dried up after sitting over night (so perhaps it's something else - maybe oil/sludge dripping it's residue)?

Hopefully I'm just paranoid . I have a 3 hour commute on the way home (in traffic) so I'm guessing that will be the final test to see if it's the brakes (assuming a 3 hour drive in traffic would empty the fluid even with the smallest leak)???

Thanks!
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post #2 of 8 (permalink) Old 07-29-2016, 01:15 PM
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If brake fluid is being pumped out of a leak some where (won't be in the middle of a line unless the lines themselves are rusting through from the inside) the level will drop. If you have a pin hole (rust through) in the line some one other than a pet can push the brake pedal while you are under the car looking to observe a faint atomized mist of spraying brake fluid.

Think power washer here. Brake line pressure is on average 1,500 psi for drum brakes and 3,000 psi for disc brakes (there is a difference between the two master cylinders to generate the difference in line pressure). If you have a pin hole in the line or a fitting is leaking fluid will come out (and air gets back in).

If you have a bad wheel cylinder (whether disc or drum) the fluid will leak around the seal and make a mess.

If brake fluid level in the master cylinder isn't dropping and brakes still work, you can look for a power steering leak as a possible source, it is a clear hydraulic fluid; SAE 10 in weight. ATF is also 10 weight hydraulic oil, but it is dyed red for that reason (so you can distinguish a Tranny leak from the usual SBC oil leak).

Big Dave
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post #3 of 8 (permalink) Old 07-29-2016, 02:02 PM Thread Starter
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Thanks, Dave. I'm sure it wasn't the power steering since the drop was all the way in front of my car (67 Impala), I checked all the fittings/hoses in that area and they were dry.

So if I'm understanding what you're saying correctly - even a pin hole leak would drain the master cylinder if I'm always driving in traffic and using the brakes??? In that particular situation, how quickly would I notice the master cylinder going low and/or my brake pedal dropping to the floor (few hours, few days, months...etc...??)? Reason I'm asking is because I'm pretty sure I don't have a leak; I'll be driving home in 3 hours worth of traffic today and I'm wondering if that will be long enough for me to notice a problem?

Thanks!
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post #4 of 8 (permalink) Old 07-29-2016, 03:07 PM
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Well the first airplane I learned to fly (an Aeronca L-16A made in 1950) had one gauge; an altimeter. Not of much use to you. But it also had a drug store suction cup mounted compass (next to useless, but better than nothing), and a cork with a bent wire stuck into it that served as a gas gauge because it floated on top of the gas with the wire sticking through a small hole in the gas cap. A very simple plane made of electrical conduit bolted together and canvas with all controls powered by your moving the stick and rudder pedals (wire cables instead of hydraulics).

As I flew I could watch the wire, that spun constantly, sink lower compared to the planes front cowl as we burned fuel. You could do something similar with your brake reservoir (require removing the hood temporarily as you drove around). A red line painted on the wire with a fixed marker could warn you that you are low on fluid before you actually sucked air resulting in a complete brake failure.

If you think the emergency brakes will actually work in an emergency you should experiment with this concept in a large vacant parking lot, also devoid of lights on poles as your car will probably end up skidding side ways. It is how movie stunt drivers get cars to go out of control in movies on cue (spinning wildly, or rolling the car over so keep the speed down).

Other wise I would get the vehicle steam cleaned then use Gunk brand Motor Shampoo to thoroughly degrease the engine compartment. Once clean and dry you should be able to identify most of your leaks. Oil on the bottom of the car can come from any where above as the fan blows a lot of wind through the engine compartment.

SBC are like Harley motorcycle engines, it was designed before the EPA. They actually were intended to dump oil on the roadway as you drove (your 1962 was the first year to get a PCV valve and not rely upon a road draft tube for ventilation). Look at old black and white movies filmed in the fifties and you can tell an actual road from a movie lot shot by the black streak of motor oil that ran down the center of every traffic lane back then. It takes a bit of work and non-original (pretty blue) neoprene rubber gaskets and some body work to repair motor sheet metal to slow those leaks down.

Valve covers, front and rear crankshaft seal (your '62 used a piece of rope when built originally for a rear main seal), oil canister O-ring, and the copper washer at the bottom of the canister as well as the oil drain plug all leaked oil more or less continually. This is ignoring the oil fumes coming out of the vent and any leaky oil pressure gauge plumbing. The standing joke about hogs is: "Does your Harley leak?" "No; then you are out of oil!"

Big Dave
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post #5 of 8 (permalink) Old 07-29-2016, 03:37 PM Thread Starter
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hahaha... i think i'll risk it. the emergency brakes don't work, i have 4 drum brakes so it's not like i have superb stopping capabilities anyway. worst comes to worst i'll jump out the window if the brakes go out... been there, done that! haha j/k .

i double checked and i doubt the line is leaking. will wash off the sludge and recheck this weekend just for piece of mind.

thanks for the help .
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post #6 of 8 (permalink) Old 07-29-2016, 06:07 PM Thread Starter
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Quote:
Originally Posted by Big Dave View Post
Well the first airplane I learned to fly (an Aeronca L-16A made in 1950) had one gauge; an altimeter. Not of much use to you. But it also had a drug store suction cup mounted compass (next to useless, but better than nothing), and a cork with a bent wire stuck into it that served as a gas gauge because it floated on top of the gas with the wire sticking through a small hole in the gas cap. A very simple plane made of electrical conduit bolted together and canvas with all controls powered by your moving the stick and rudder pedals (wire cables instead of hydraulics).

As I flew I could watch the wire, that spun constantly, sink lower compared to the planes front cowl as we burned fuel. You could do something similar with your brake reservoir (require removing the hood temporarily as you drove around). A red line painted on the wire with a fixed marker could warn you that you are low on fluid before you actually sucked air resulting in a complete brake failure.

If you think the emergency brakes will actually work in an emergency you should experiment with this concept in a large vacant parking lot, also devoid of lights on poles as your car will probably end up skidding side ways. It is how movie stunt drivers get cars to go out of control in movies on cue (spinning wildly, or rolling the car over so keep the speed down).

Other wise I would get the vehicle steam cleaned then use Gunk brand Motor Shampoo to thoroughly degrease the engine compartment. Once clean and dry you should be able to identify most of your leaks. Oil on the bottom of the car can come from any where above as the fan blows a lot of wind through the engine compartment.

SBC are like Harley motorcycle engines, it was designed before the EPA. They actually were intended to dump oil on the roadway as you drove (your 1962 was the first year to get a PCV valve and not rely upon a road draft tube for ventilation). Look at old black and white movies filmed in the fifties and you can tell an actual road from a movie lot shot by the black streak of motor oil that ran down the center of every traffic lane back then. It takes a bit of work and non-original (pretty blue) neoprene rubber gaskets and some body work to repair motor sheet metal to slow those leaks down.

Valve covers, front and rear crankshaft seal (your '62 used a piece of rope when built originally for a rear main seal), oil canister O-ring, and the copper washer at the bottom of the canister as well as the oil drain plug all leaked oil more or less continually. This is ignoring the oil fumes coming out of the vent and any leaky oil pressure gauge plumbing. The standing joke about hogs is: "Does your Harley leak?" "No; then you are out of oil!"

Big Dave
Quick question - In my 67 Impala I have a dual master cylinder. Out of curiosity I did some research online regarding single VS dual master cylinders and was hoping someone could clarify something for me; does a dual master cylinder serve as a backup in case one brake line goes out? Meaning, if the fluid going through my rear brake line seeps out (causing rear brakes to fail), would the fluid going to the front brakes keep them fully functional (assuming the leak was in the line, not the cylinder)?

Thanks!
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post #7 of 8 (permalink) Old 07-29-2016, 07:40 PM
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You got half of it. A dual brake system was instituted in 1967 to meet federal safety standards enacted in 1966 (seat belts weren't required until 1967 as well, but GM made them standard equipment instead of an option in 1966). It is basically two separate brake systems operated with one pedal, The front reservoir operates the rear brakes and the rear holds fluid for the front. If you get a leak in the back the front brakes continue to work when the rear brakes fail completely and vice versa.

There is a magnetic switch attached to the piston inside the master cylinder. If the piston travels too far forward it trips the "BRAKE" light on the dash. The Brake Light and the fact that you just hit the car in front of you is to let you know your brakes are no longer working correctly. This is the same Brake light that comes on if you activate the emergency brake in an attempt to keep from hitting the car in front of you (assumes you can find it and your knee has enough room to push it in without hitting the steering wheel as it does with me).

If only the rear brakes lock up the rear end will probably try and pass you. This is because you took your foot off the gas so the car starts to slow down, but because the rear brakes are locked you are now floating the rear of the car on a patch of liquid rubber. As such the rolling resistance of the front tires exceeds the friction offered by the sliding rear tires so it spins around. Until the tires slide off the puddle of rubber then it snaps back almost instantly in the other direction to start the fun ride over again.

This behavior is why they have Anti-Skid Brakes (ASB) on computer controlled cars now. The people that dictate these changes feel that adding stopping distance to what could be accomplished with out ASB is worth not scarring a teenager texting while driving. It is also a lot of fun to watch when a car pulls off the road in a panic stop because the side of the car that hits the grass first stops having any braking effort (skidding on grass is a fast way to try and lock up brakes). So the car immediately jerks back onto the road you were trying to pull off of attempting to cross the traffic lane to hit a concrete barrier (or on coming traffic if there is no barrier) at a ninety degree angle. This usually gets you hit by two or more cars.

I used to be a cop (it is how I worked my way through college) so I saw and investigated a lot of traffic wrecks while working for 13 years (I got three degrees). You are not going to believe this, but very few people on the road actually know how to drive. (Power steering, power brakes, automatic transmissions, and distractions such as phones, eating putting on make up while sitting behind the steering wheel of two tons of steel moving at 70 mph can do a lot of damage when the point in an on going accident arrives where "then she lost control of the car" as the old Henny Youngman joke goes.

I used to race as often as I could in as many venues as I could. The best driving training I got was in racing with the SCCA in autocross and rally driving. Nothing like killing cones to improve your knowledge of where the wheels are how to heel and toe and perform power skids drifting through turns at full throttle before that became a sport in itself.

Big Dave
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post #8 of 8 (permalink) Old 07-29-2016, 08:24 PM Thread Starter
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Quote:
Originally Posted by Big Dave View Post
You got half of it. A dual brake system was instituted in 1967 to meet federal safety standards enacted in 1966 (seat belts weren't required until 1967 as well, but GM made them standard equipment instead of an option in 1966). It is basically two separate brake systems operated with one pedal, The front reservoir operates the rear brakes and the rear holds fluid for the front. If you get a leak in the back the front brakes continue to work when the rear brakes fail completely and vice versa.

There is a magnetic switch attached to the piston inside the master cylinder. If the piston travels too far forward it trips the "BRAKE" light on the dash. The Brake Light and the fact that you just hit the car in front of you is to let you know your brakes are no longer working correctly. This is the same Brake light that comes on if you activate the emergency brake in an attempt to keep from hitting the car in front of you (assumes you can find it and your knee has enough room to push it in without hitting the steering wheel as it does with me).

If only the rear brakes lock up the rear end will probably try and pass you. This is because you took your foot off the gas so the car starts to slow down, but because the rear brakes are locked you are now floating the rear of the car on a patch of liquid rubber. As such the rolling resistance of the front tires exceeds the friction offered by the sliding rear tires so it spins around. Until the tires slide off the puddle of rubber then it snaps back almost instantly in the other direction to start the fun ride over again.

This behavior is why they have Anti-Skid Brakes (ASB) on computer controlled cars now. The people that dictate these changes feel that adding stopping distance to what could be accomplished with out ASB is worth not scarring a teenager texting while driving. It is also a lot of fun to watch when a car pulls off the road in a panic stop because the side of the car that hits the grass first stops having any braking effort (skidding on grass is a fast way to try and lock up brakes). So the car immediately jerks back onto the road you were trying to pull off of attempting to cross the traffic lane to hit a concrete barrier (or on coming traffic if there is no barrier) at a ninety degree angle. This usually gets you hit by two or more cars.

I used to be a cop (it is how I worked my way through college) so I saw and investigated a lot of traffic wrecks while working for 13 years (I got three degrees). You are not going to believe this, but very few people on the road actually know how to drive. (Power steering, power brakes, automatic transmissions, and distractions such as phones, eating putting on make up while sitting behind the steering wheel of two tons of steel moving at 70 mph can do a lot of damage when the point in an on going accident arrives where "then she lost control of the car" as the old Henny Youngman joke goes.

I used to race as often as I could in as many venues as I could. The best driving training I got was in racing with the SCCA in autocross and rally driving. Nothing like killing cones to improve your knowledge of where the wheels are how to heel and toe and perform power skids drifting through turns at full throttle before that became a sport in itself.

Big Dave
haha... No use worrying about break leaks if i have a backup cylinder to save me! j/k . Good to know that's how it works.

I totally feel you about the newer cars having all sorts of gadgets/technology that people rely on. I'm happy with my 67 - turn the key a certain way to start her up, play in the steering wheel so you actually have to work to stay in the lane, it drives like a boat, 4 wheel drums to stop on a dime (after you spend a dollar!), every irregular sound I hear and I'm checking the entire vehicle for issues! monitoring all the leaks every week (like you said - if it doesn't leak, then i'm out of oil!) .

Thanks for your input!
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