Bleeding brakes
Thread Starter
Intermediate
Joined: Nov 2021
Posts: 35
Likes: 6
Bleeding brakes
A couple of years ago, i used the gravity method to bleed all of the brakes on my C3. It worked well just like in the HOP video i found on YouTube.
Well, for the last day and a half i have been trying to do it again and it is a NO-GO. jacked up the front end and lowered the back end, cracked all 4 bleeder screws and nothing. took out the bleeders and made sure they were clean. Let it sit overnight with the bleeders open and still nothing. Used a vacuum bleeder on the back 2 calipers this morning and now have tilted the car the other way and opened the front caliper bleeders and NOTHING. I will wind up vacuum bleeding those also, but i was just wondering if the gravity bleed not working is an indication of a problem in the system.
ANY THOUGHTS????
Well, for the last day and a half i have been trying to do it again and it is a NO-GO. jacked up the front end and lowered the back end, cracked all 4 bleeder screws and nothing. took out the bleeders and made sure they were clean. Let it sit overnight with the bleeders open and still nothing. Used a vacuum bleeder on the back 2 calipers this morning and now have tilted the car the other way and opened the front caliper bleeders and NOTHING. I will wind up vacuum bleeding those also, but i was just wondering if the gravity bleed not working is an indication of a problem in the system.
ANY THOUGHTS????
Popular Reply
Feb 16, 2024, 11:55 AM
Thread Starter
Intermediate
Joined: Nov 2021
Posts: 35
Likes: 6
Hello to all that responded to my original question! Just to let ya'll know what i did, is i borrowed a friends vacuum bleeder and used it on all 6 bleeder fittings. I did not get 100% positive results as i never completelyt got rid of bubbles in the plastic bleeder lines. I did seal the bleeder screws using some grease, but, like i said, i still saw bubbles.
The next day i tried to see if the gravity bleed would work and, lo and behold, it did work. I used the 90 deg. fitting that came with the vacuum bleeder and just ran a 6 inch piece of clear tubing straight up and opened the bleeders. after 1/2 hour or so all of the calipers had brake fluid for a solid 3-4 inches above the bleeders. Closed the bleeders and refilled the Master Cylinder and now i have a good firm pedal!
Thank you for all of your inputs....they were much appreciated!
Hoseman653
The next day i tried to see if the gravity bleed would work and, lo and behold, it did work. I used the 90 deg. fitting that came with the vacuum bleeder and just ran a 6 inch piece of clear tubing straight up and opened the bleeders. after 1/2 hour or so all of the calipers had brake fluid for a solid 3-4 inches above the bleeders. Closed the bleeders and refilled the Master Cylinder and now i have a good firm pedal!
Thank you for all of your inputs....they were much appreciated!
Hoseman653
6th Gear
Joined: Feb 2024
Posts: 6
Likes: 2
From: Logansport IN
Not sure I can pin point your problem but just finished my dads 76 on Friday and went through a few steps to narrow down his issue.
Is pedal firm if you pump it? Does it stay firm when you hold it after 3 or 4 pumps with all bleeders closed?
Is pedal firm if you pump it? Does it stay firm when you hold it after 3 or 4 pumps with all bleeders closed?
Le Mans Master
Joined: Aug 2017
Posts: 8,336
Likes: 2,810
From: Cool Northern Michigan
The lid on the master is loose, right?
I would question if your Mity-Vac is even working. Attach another Vac gauge in line to test it.
DOT3 likes to destroy those diaphragms inside.
Eventually, your Mity-Vac will get fluid moving, just keep at it. But start with one bleeder at a time, preferably outer-right-rear.
Myself, I frown on touching the pedal with any bleeder open. You will just create more issues and trip the Proportioning Valve.
Maybe you have already?
I would question if your Mity-Vac is even working. Attach another Vac gauge in line to test it.
DOT3 likes to destroy those diaphragms inside.
Eventually, your Mity-Vac will get fluid moving, just keep at it. But start with one bleeder at a time, preferably outer-right-rear.
Myself, I frown on touching the pedal with any bleeder open. You will just create more issues and trip the Proportioning Valve.
Maybe you have already?
Drifting
Joined: Sep 2016
Posts: 1,489
Likes: 524
From: Ventura California
I’m following this thread.
Ive spent all day yesterday and today trying to get some sort of pressure on my brake pedal.
I did not gravity bleed but did try and use a vacuum device which worked for the front brakes.
No fluid coming out of the back bleeders at all.
My brake lines are new and have never had fluid in them.
Strangely, the main back brake line from the proportioning block was blocked. After blowing it out with air, I was able to get fluid flowing.
Anyways, this is a pain in the butt!
Ive spent all day yesterday and today trying to get some sort of pressure on my brake pedal.
I did not gravity bleed but did try and use a vacuum device which worked for the front brakes.
No fluid coming out of the back bleeders at all.
My brake lines are new and have never had fluid in them.
Strangely, the main back brake line from the proportioning block was blocked. After blowing it out with air, I was able to get fluid flowing.
Anyways, this is a pain in the butt!
6th Gear
Joined: Feb 2024
Posts: 6
Likes: 2
From: Logansport IN
I’m following this thread.
Ive spent all day yesterday and today trying to get some sort of pressure on my brake pedal.
I did not gravity bleed but did try and use a vacuum device which worked for the front brakes.
No fluid coming out of the back bleeders at all.
My brake lines are new and have never had fluid in them.
Strangely, the main back brake line from the proportioning block was blocked. After blowing it out with air, I was able to get fluid flowing.
Anyways, this is a pain in the butt!
Ive spent all day yesterday and today trying to get some sort of pressure on my brake pedal.
I did not gravity bleed but did try and use a vacuum device which worked for the front brakes.
No fluid coming out of the back bleeders at all.
My brake lines are new and have never had fluid in them.
Strangely, the main back brake line from the proportioning block was blocked. After blowing it out with air, I was able to get fluid flowing.
Anyways, this is a pain in the butt!
Replaced Master Cyclinder, made sure to bench bleed well before we installed. 2 man bleed on all 4 corners and for now all is well.
Not sure if your issue is the MC, but hope this helps in some way.
Instructor
Joined: Aug 2022
Posts: 209
Likes: 107
Re did brakes rotors soft lines and master cylinder all the way around and it took a gravity and 2 man 4 or 5 times to get it right. Don't know why it's such a problem
w/C3's but lot's of posters on here echoing your situation. Get 'em to where they feel good, drive around a good bit and hit 'em again. Repeat if needed 'till they shore up is what worked for me. I must say that once I got 'em right they have performed perfectly.
w/C3's but lot's of posters on here echoing your situation. Get 'em to where they feel good, drive around a good bit and hit 'em again. Repeat if needed 'till they shore up is what worked for me. I must say that once I got 'em right they have performed perfectly.
Drifting
Joined: Sep 2016
Posts: 1,489
Likes: 524
From: Ventura California
Can some one explain gravity bleeding?
How is it done?
BTW, my MC is brand new so I suppose it could be that but I’m not convinced. I could possible have a fitting not sealing. When I put the car away I felt around the the hoses and had a bit of brake fluid on it.
How is it done?
BTW, my MC is brand new so I suppose it could be that but I’m not convinced. I could possible have a fitting not sealing. When I put the car away I felt around the the hoses and had a bit of brake fluid on it.
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Gravity bleeding. As the name implies. Let Gravity do the work.
Basically, put a piece of tubing on the bleeder you wish to bleed. I like about a 2 foot chunk. Pointing into a catch container.
Remove lid from master cylinder. Top up fluid. Open bleeder and crack open a beer.
Fluid will flow out the bleeder screw by gravity. Generally very slowly, thus the beer. Top up the master as it gets low. Do not allow it to go empty. After a master cylinder or 2 full of fluid. Close bleeder. Move on to the next one.
If your lines are completely empty the 2 man method is good to get them started. Then go to the gravity method. Use of the proportioning valve lock tool is highly recommended so as not to trip the safety.
Basically, put a piece of tubing on the bleeder you wish to bleed. I like about a 2 foot chunk. Pointing into a catch container.
Remove lid from master cylinder. Top up fluid. Open bleeder and crack open a beer.
Fluid will flow out the bleeder screw by gravity. Generally very slowly, thus the beer. Top up the master as it gets low. Do not allow it to go empty. After a master cylinder or 2 full of fluid. Close bleeder. Move on to the next one.
If your lines are completely empty the 2 man method is good to get them started. Then go to the gravity method. Use of the proportioning valve lock tool is highly recommended so as not to trip the safety.
Le Mans Master
Joined: Aug 2017
Posts: 8,336
Likes: 2,810
From: Cool Northern Michigan
hoseman653 & Tuna Joe,
The Master is the highest point of the entire C3 brake system. All six bleeder screws are below that level.
Gravity Bleeding Method is one of best methods, but also the slowest. People get in a hurry and play with the brake pedal.
All that does is close the Proportioning Valve in either the front system or rear system depending on where a bleeder is open.
That event is the safety function of the Prop Valve; to close off a pressure leak, fore or aft.
Theoretically, you could attach six clear hoses, to six open bleeders, into six clear water bottles. Then, sit next to the master with a car magazine in one hand and a bottle of DOT3 in the other.
But if the Prop Valve is wonky you can forget all about that plan.
For those that insist on touching the brake pedal, there is a tool that locks the Prop Valve in a neutral position, keeping it from tripping.
A picture of that tool can be seen by clicking on my avatar, look for brake bleeding photo album.
Basically, there are five Brake Bleeding Methods:
Pedal method
Gravity method
Motive Pressure method
Vacuum pump method
Let somebody else do it method
The Master is the highest point of the entire C3 brake system. All six bleeder screws are below that level.
Gravity Bleeding Method is one of best methods, but also the slowest. People get in a hurry and play with the brake pedal.
All that does is close the Proportioning Valve in either the front system or rear system depending on where a bleeder is open.
That event is the safety function of the Prop Valve; to close off a pressure leak, fore or aft.
Theoretically, you could attach six clear hoses, to six open bleeders, into six clear water bottles. Then, sit next to the master with a car magazine in one hand and a bottle of DOT3 in the other.
But if the Prop Valve is wonky you can forget all about that plan.
For those that insist on touching the brake pedal, there is a tool that locks the Prop Valve in a neutral position, keeping it from tripping.
A picture of that tool can be seen by clicking on my avatar, look for brake bleeding photo album.
Basically, there are five Brake Bleeding Methods:
Pedal method
Gravity method
Motive Pressure method
Vacuum pump method
Let somebody else do it method
Drifting
Joined: Mar 2012
Posts: 1,932
Likes: 1,509
From: Here, There and Everywhere
Get this and be done in 20 minutes! You can get adapters for just about any master cylinder so it can be used for multiple vehicles. For what a shop charges per hour for labor, this pressure bleeder will pay for itself on the first use. Why struggle?
Thread Starter
Intermediate
Joined: Nov 2021
Posts: 35
Likes: 6
proportioning valve
The lid on the master is loose, right?
I would question if your Mity-Vac is even working. Attach another Vac gauge in line to test it.
DOT3 likes to destroy those diaphragms inside.
Eventually, your Mity-Vac will get fluid moving, just keep at it. But start with one bleeder at a time, preferably outer-right-rear.
Myself, I frown on touching the pedal with any bleeder open. You will just create more issues and trip the Proportioning Valve.
Maybe you have already?
I would question if your Mity-Vac is even working. Attach another Vac gauge in line to test it.
DOT3 likes to destroy those diaphragms inside.
Eventually, your Mity-Vac will get fluid moving, just keep at it. But start with one bleeder at a time, preferably outer-right-rear.
Myself, I frown on touching the pedal with any bleeder open. You will just create more issues and trip the Proportioning Valve.
Maybe you have already?
Pro
Joined: Aug 2009
Posts: 704
Likes: 503
From: Temple, TX
This. All of this. But instead of the chains, use a giant c-clamp to hold the plate onto the master cylinder reservoir.
Le Mans Master
Joined: Aug 2017
Posts: 8,336
Likes: 2,810
From: Cool Northern Michigan
hoseman653,
Usually, a few quick jabs of the brake pedal, (all bleeders closed) will "reset" the Prop Valve.
If you suspect the P.V. is stuck in the rearward position, sometimes cracking open a front bleeder will shift the piston forward. And vise-versa.
Its spring loaded and does a fair job of getting you home with half your brakes, in the event you lose some fluid.
I have a picture of the internal workings of the Prop Valve and a picture of the tool that locks the little piston in place.
Click on my avatar, look for brake bleeding photo album.
The Prop Valve has an electrical switch on top that activates the brake warning light. The switch can be removed while on the car and the tool can be inserted without loss of fluid.
A note about Proportioning Valves. Earlier model years did not have one. They had a distribution block.
The Prop Valve was under the master at first, then later moved down to the frame.
Not all warning switches are the same. They changed design, so it's imperative you purchase the correct yr. Otherwise, your wire harness will not fit.
The Prop Valve seldom fails. Not really too much to it, Spring, piston, chunk of brass. Some people have had luck rebuilding them.
Usually, a few quick jabs of the brake pedal, (all bleeders closed) will "reset" the Prop Valve.
If you suspect the P.V. is stuck in the rearward position, sometimes cracking open a front bleeder will shift the piston forward. And vise-versa.
Its spring loaded and does a fair job of getting you home with half your brakes, in the event you lose some fluid.
I have a picture of the internal workings of the Prop Valve and a picture of the tool that locks the little piston in place.
Click on my avatar, look for brake bleeding photo album.
The Prop Valve has an electrical switch on top that activates the brake warning light. The switch can be removed while on the car and the tool can be inserted without loss of fluid.
A note about Proportioning Valves. Earlier model years did not have one. They had a distribution block.
The Prop Valve was under the master at first, then later moved down to the frame.
Not all warning switches are the same. They changed design, so it's imperative you purchase the correct yr. Otherwise, your wire harness will not fit.
The Prop Valve seldom fails. Not really too much to it, Spring, piston, chunk of brass. Some people have had luck rebuilding them.
Safety Car
Joined: May 2001
Posts: 4,749
Likes: 1,642
From: Fairfax Virginia
Before opening your veins over getting the air out of the system take a quick look at the Phoenix Reverse Bleeder and the variations. I use one and it pushes the air and fluid UP from down by the tire. I use a turkey baster to help control the fluid levels and a bucket under the master cylinder. I have not spilled any by accident, the bowl is there for insurance.
Pushing the fluid UP let's all the nasty dirty fluid and any trapped air gets the job done easily. It makes flushing your brakes less work with great results. It also did the hydraulic clutch master cylinder in out 1993 Chevy Pick-up.
Pushing air up really does help get all the air out of the system. I have done a bunch of cars, motorcycles and even my Cessna 172 with this great device.
Pushing the fluid UP let's all the nasty dirty fluid and any trapped air gets the job done easily. It makes flushing your brakes less work with great results. It also did the hydraulic clutch master cylinder in out 1993 Chevy Pick-up.
Pushing air up really does help get all the air out of the system. I have done a bunch of cars, motorcycles and even my Cessna 172 with this great device.
Thread Starter
Intermediate
Joined: Nov 2021
Posts: 35
Likes: 6
Hello to all that responded to my original question! Just to let ya'll know what i did, is i borrowed a friends vacuum bleeder and used it on all 6 bleeder fittings. I did not get 100% positive results as i never completelyt got rid of bubbles in the plastic bleeder lines. I did seal the bleeder screws using some grease, but, like i said, i still saw bubbles.
The next day i tried to see if the gravity bleed would work and, lo and behold, it did work. I used the 90 deg. fitting that came with the vacuum bleeder and just ran a 6 inch piece of clear tubing straight up and opened the bleeders. after 1/2 hour or so all of the calipers had brake fluid for a solid 3-4 inches above the bleeders. Closed the bleeders and refilled the Master Cylinder and now i have a good firm pedal!
Thank you for all of your inputs....they were much appreciated!
Hoseman653
The next day i tried to see if the gravity bleed would work and, lo and behold, it did work. I used the 90 deg. fitting that came with the vacuum bleeder and just ran a 6 inch piece of clear tubing straight up and opened the bleeders. after 1/2 hour or so all of the calipers had brake fluid for a solid 3-4 inches above the bleeders. Closed the bleeders and refilled the Master Cylinder and now i have a good firm pedal!
Thank you for all of your inputs....they were much appreciated!
Hoseman653
Le Mans Master
Joined: Aug 2017
Posts: 8,336
Likes: 2,810
From: Cool Northern Michigan
Normally, a gravity bleed would be waiting for the brake fluid to seek the lowest spot and carry bubbles with it. The lowest spot would be a water bottle on the ground with a clear hose. Your method, a standpipe, would work, but I wonder if a six inch high hose would clear out several feet of brake-line.
You just invented the Anti-gravity method.
Congrats.
You just invented the Anti-gravity method.
Congrats.
Thread Starter
Intermediate
Joined: Nov 2021
Posts: 35
Likes: 6
The bleeder screw is the highest point in the line downstream of the Master Cylinder. If the fluid rises 6 inches above the bleeder screw it would have pushed any air at least to the bleeder and the 6 inch fluid column would have provided a path for any air bubbles to escape.
Le Mans Master
Joined: Aug 2017
Posts: 8,336
Likes: 2,810
From: Cool Northern Michigan
Well, yes. No. Maybe. Not sure. If it were only that easy.
On paper it looks good.
In theory it sounds good.
But it's a C3. All papers, theories and old methods are out the window.
Worst damn brakes I have seen in my life to bleed.
On paper it looks good.
In theory it sounds good.
But it's a C3. All papers, theories and old methods are out the window.
Worst damn brakes I have seen in my life to bleed.