Problem bleeding brake lines
Thread Starter
Heel & Toe
Joined: Nov 2017
Posts: 20
Likes: 0
Problem bleeding brake lines
About 5 months ago I put new brake calipers on the 77 vette. I then put in dot 5 brake fluid and gravity bleed it. I keep having problems with the brake petal getting soft. So I go to bleed the system again this time with a Power Bleeder. So I pumped it up to 10 psi and opened the rear right inner bleed screw and no brake fluid drains. Now the brake petal is at the floor. Before I put the new calipers on I was using Dot 4. I didn't put new brake lines on. I purged the Dot 4 before using the Dot 5. but, What I think has happened is the glycol and silicon based brake fluid mixed and clogged up the lines. What im wondering is how to complete purge the lines of contaminated dot 5? Also, should I just go back to using glycol based brake fluid like Dot 5.1 or stay with the silicon based Dot 5?
Le Mans Master
Joined: Aug 2017
Posts: 8,336
Likes: 2,809
From: Cool Northern Michigan
You can get Dot 3 in a silicone I believe. So you have Dot 3, Dot 4, Dot 5 mix. No wonder.
If it were mine, I would buy a bottle of denatured alcohol, pour that into a EMPTY master cylinder. Apply some pressure to the MC with your Power Bleeder.
Start cracking bleeder screws. Consider this a flush cleansing. Bleed in any order, does not matter yet. Close bleeders.
Then with several bottles of Dot 3 I would half fill the Power Bleeder tank and pressurize the master. Crack bleeders open again. This time bleed in proper order. Use a clear hose to monitor the clarity of fluid. Lightly pump the brake pedal a couple times while pressurized to clear the caliper bores.
When you are confident the old DOT 3,4,5 are gone, then you should be good to go.
If it were mine, I would buy a bottle of denatured alcohol, pour that into a EMPTY master cylinder. Apply some pressure to the MC with your Power Bleeder.
Start cracking bleeder screws. Consider this a flush cleansing. Bleed in any order, does not matter yet. Close bleeders.
Then with several bottles of Dot 3 I would half fill the Power Bleeder tank and pressurize the master. Crack bleeders open again. This time bleed in proper order. Use a clear hose to monitor the clarity of fluid. Lightly pump the brake pedal a couple times while pressurized to clear the caliper bores.
When you are confident the old DOT 3,4,5 are gone, then you should be good to go.
Last edited by HeadsU.P.; Jul 28, 2019 at 09:26 PM.
Team Owner
Joined: Jun 2001
Posts: 23,353
Likes: 1,054
From: Virginia USA
You can get Dot 3 in a silicone I believe. So you have Dot 3, Dot 4, Dot 5 mix. No wonder.
If it were mine, I would buy a bottle of denatured alcohol, pour that into a EMPTY master cylinder. Apply some pressure to the MC with your Power Bleeder.
Start cracking bleeder screws. Consider this a flush cleansing. Bleed in any order, does not matter yet. Close bleeders.
Then with several bottles of Dot 3 I would half fill the Power Bleeder tank and pressurize the master. Crack bleeders open again. This time bleed in proper order. Use a clear hose to monitor the clarity of fluid. Lightly pump the brake pedal a couple times while pressurized to clear the caliper bores.
When you are confident the old DOT 3,4,5 are gone, then you should be good to go.
If it were mine, I would buy a bottle of denatured alcohol, pour that into a EMPTY master cylinder. Apply some pressure to the MC with your Power Bleeder.
Start cracking bleeder screws. Consider this a flush cleansing. Bleed in any order, does not matter yet. Close bleeders.
Then with several bottles of Dot 3 I would half fill the Power Bleeder tank and pressurize the master. Crack bleeders open again. This time bleed in proper order. Use a clear hose to monitor the clarity of fluid. Lightly pump the brake pedal a couple times while pressurized to clear the caliper bores.
When you are confident the old DOT 3,4,5 are gone, then you should be good to go.
Pro
Joined: Mar 2014
Posts: 529
Likes: 113
From: Texas
By mixing the fluids I would bet you have damaged the master cylinder and hoses and seals in calipers. You can flush out the system and see if you got lucky. The only high temp fluid to use is DOT 5.1, it works with DOT 3 and DOT 4 fluid without any issues. DOT 5 fluid is used on dedicated race cars as the fluid is changed on a maintenance schedule before every race, just like the engine oil is changed.
Race Director
Joined: Nov 2006
Posts: 13,068
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From: Sunshine Coast, Queensland, Australia
2025 C3 of the Year Finalist - Modified
2024 C3 of the Year Finalist- Modified
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Cruise-In VIII Veteran
I don't know guy's. I changed my 77 over to Dot 5 years ago. As in 20 years ago. No issues what so ever. It never absorbs moisture. And I know a fair few who have switched. Never heard of it causing a clog or any issue whatsoever. If you get a tight pedal after bleeding. And then in a month or so, you are getting a soft pedal. I'd be looking for a leak. A very slow weep as it were.
If you are getting no fluid out of one bleeder. Id be pulling that caliper apart.
The changing fluid stuff mentioned earlier sounds like pure bull to me
If you are getting no fluid out of one bleeder. Id be pulling that caliper apart.
The changing fluid stuff mentioned earlier sounds like pure bull to me
Pro
Joined: Mar 2014
Posts: 529
Likes: 113
From: Texas
Even though DOT 5 doesn’t absorb water, it can’t/won’t prevent moisture from entering the brake system. And since the water isn’t absorbed by DOT 5, moisture puddles and causes localized corrosion within the brake system. As funny as it sounds, DOT 3, 4, and 5.1 absorb moisture, which in turn eliminates the puddling that can cause corrosion. More importantly, when brake fluid heats up, water trapped inside the brake lines (but not absorbed by the brake fluid) is converted from liquid to vapor. Steam compresses easier than liquid. With this in mind, imagine barreling down the road at high speed and hitting the brakes. When the hydraulics sends DOT 5 fluid through a pocket of steam in the line, that drop in pressure creates a soft pedal. Combining even trace amounts of a glycol-based brake fluid with DOT 5 can cause the two incompatible fluids to gel, resulting in poor braking. Converting to DOT 5 also requires thorough flushing and removing ALL traces of the old fluid to avoid seal damage.
Dr. Detroit
Joined: Mar 2012
Posts: 10,090
Likes: 4,015
From: New Braunfels Texas
We always used DOT 5 in my Dads Street Rods because he was weary of getting fluid on a $10,000 paint job (In 2000 money!).........it works great and you will never have any problem.
10 out of 10 people who have issues with the stuff have them due to contamination......you simply CANNOT use it in a previously filled system......everything needs to be new.....it doesn't matter how much you flush it.....the only real things you can save if converting is the steel lines.......DOT5 was created for race cars as it has a higher boiling point, but other than that and the fact that it does not eat paint, there is no real advantage...
If I were you I would change all four calipers, master, and soft lines.....and flush the hard lines......fill it with DOT3 and do not touch it again for a long time
Jebby
10 out of 10 people who have issues with the stuff have them due to contamination......you simply CANNOT use it in a previously filled system......everything needs to be new.....it doesn't matter how much you flush it.....the only real things you can save if converting is the steel lines.......DOT5 was created for race cars as it has a higher boiling point, but other than that and the fact that it does not eat paint, there is no real advantage...
If I were you I would change all four calipers, master, and soft lines.....and flush the hard lines......fill it with DOT3 and do not touch it again for a long time
Jebby
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Thread Starter
Heel & Toe
Joined: Nov 2017
Posts: 20
Likes: 0
Before I did the new calipers.. the car was sitting for a year or two with no brakes. All the seals in the original calipers got ate up. The brake fluid drained out long ago soo I assumed the lines where clear. Lesson learned dont assume things when it comes to vettes. I drained some of the bad dot5 out and the color of fluid has changed from purple to a light green. Yet fluid in the master cylinder is still purple. Another question is can the distilled alcohol damage the brake system? Also, the main problem with Dot 5 is finding a place that sells it, this stuff is expensive $28 a quart.
Calipers used: https://www.ecklerscorvette.com/corv...1965-1982.html
Calipers used: https://www.ecklerscorvette.com/corv...1965-1982.html
Le Mans Master
Joined: Oct 2010
Posts: 6,900
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From: melbourne florida
2023 C3 of the Year Finalist - Modified
I'd clean the calipers and reassemble them, make sure the hoses are good. My experience is the o ring calipers are more forgiving.I think I'd flush it with clean brake fluid. I'm not a fan of solvent in brake components.
Last edited by 7t9l82; Jul 29, 2019 at 01:19 PM.
Thread Starter
Heel & Toe
Joined: Nov 2017
Posts: 20
Likes: 0
Here what going to take hoses off of all 4 calipers and just run the denatured alcohol though the lines only. Let the lines dry out. Reconnect the calipers and get a gallon of dot 3. Flush it till the fuild is clear.
Thanks for the advice soo far
Thanks for the advice soo far
Racer
Joined: Jan 2013
Posts: 287
Likes: 16
From: Florida New York
I know , this is going to sound crazy. But, do you have the calipers on the right side of the car. Left caliper, left side, right caliper
right side. Are the bleeder screws on top or the bottom of the calipers ? That'll cause problems also when trying to bleed the calipers.
right side. Are the bleeder screws on top or the bottom of the calipers ? That'll cause problems also when trying to bleed the calipers.
Advanced
Joined: Sep 2011
Posts: 73
Likes: 4
From: New York
Bleeders are on the top of calipers. Game plan is this....Silicone seal and new pistons from Corvette SS brake co, replace MC and proportioning valve, replace braided SS flex lines with new ones, totally flush calipers and lines, first with denatured alcohol and then dot 5.1 brake fluid then blow out with compressed air. . Bench bleed MC and power bleed the system
System as new Wilwwdf drilled and slotted rotors with Hawk Ceramic brake pads.
Waiting for parts to arrive, should be completed by next week
System as new Wilwwdf drilled and slotted rotors with Hawk Ceramic brake pads.
Waiting for parts to arrive, should be completed by next week