Changing from DOT 5 To DOT3 brake fluid FED UP WITH AIR BUBBLES on my 67

[Joe L.]

Re: Changing from DOT 5 To DOT3 brake fluid FED UP WITH AIR BUBBLES on my 67

Thanks Paul, I was able to get some brakes today using the gravity flow method followed up with the husband/wife method. Only able to get about 2'' of pedal above the floor, though. This lasted for only about an hour. I re-checked the pedal after changing plug wires in an effort to eliminate a skip in the engine. When I checked the pedal with the engine running, the pedal went to the floor. I cut off the engine and checked again with the same result. You could get a little brake if you pumped the pedal several times rapidly with the engine off. Either I'm still not getting all the air out or it's sucking air in somewhere. I have about rounded off the bleeders where the wrench fits. Are the bleeders available at local stores or do you get them from the brake people listed in the Driveline?

Al-----


Dorman #484-146 (boxed) or 13903 (carded in Help! section).

[Larry M.]

Re: Changing from DOT 5 To DOT3 brake fluid FED UP WITH AIR BUBBLES on my 67

Thanks Paul, I was able to get some brakes today using the gravity flow method followed up with the husband/wife method. Only able to get about 2'' of pedal above the floor, though. This lasted for only about an hour. I re-checked the pedal after changing plug wires in an effort to eliminate a skip in the engine. When I checked the pedal with the engine running, the pedal went to the floor. I cut off the engine and checked again with the same result. You could get a little brake if you pumped the pedal several times rapidly with the engine off. Either I'm still not getting all the air out or it's sucking air in somewhere. I have about rounded off the bleeders where the wrench fits. Are the bleeders available at local stores or do you get them from the brake people listed in the Driveline?

This is generally indicative of a bad/faulty master cylinder. (i.e. the master cylinder seals are not holding and are leaking by)

Larry

[Santo S.]

Re: Changing from DOT 5 To DOT3 brake fluid FED UP WITH AIR BUBBLES on my 67

I agree you have a bad master cylinder, I had the same problem couldn't get a pedal with a new Master Cylinder. (don't want to name the supplier) changed the master and never had a problem since.

[Al R.]

Re: Changing from DOT 5 To DOT3 brake fluid FED UP WITH AIR BUBBLES on my 67

Thanks Larry. I was wondering if it could be the MC. I looked up the invoice today and the purchase date is 9/8/11, though it was not put into service until Feb 2013. I could not get the brakes to stay bled then either. They did hold for about 1-2 months I think, not sure as time passes too quick, when you are not around to work on the car. Anyway, I put the effort on other things to try to finish the restoration and figured I 'd get back to that headache when possible. I did not realize it had been since Feb. until I was looking at past threads by me this afternoon to see if the MC was date coded in 67. I plan to call CSSB tomorrow morning for assistance or their recommendations. If I had another MC, I would try that to at least eliminate it as the problem or see if it is the problem. I still cannot find any signs of leakage at fittings, lines, hoses, rear of MC, or around caliper seals. If at calipers, it would have to be a small seepage, as no visible signs of fluid on the rotors, other that what I've allowed to leak out at the bleeders. If no help from CSSB, I will keep trying to bleed or purchase a MC from the local parts house to start eliminating things. From there maybe the hoses next? Bleed try & hope, I guess.

[Dennis O.]

Re: Changing from DOT 5 To DOT3 brake fluid FED UP WITH AIR BUBBLES on my 67

RE : Heating DOT5 brake fluid before installing.

I am absolutely sure of 2 things :

1. I heated my DOT5 brake fluid before installing it 15-20 years ago and my brakes are still fine on the '68.

2. I am too lazy to have gone through this procedure unless I had some very good reason to do it.

I have "Goggled" the procedure several times using different search arguments and come up with nothing. When I purchased the original DOT5 fluid back then, I believe I purchased 2 quarts to make sure I would have enough. I believe I still have one of the original sealed containers. I'm going to dig through my shelves to see if I can find this original container or anything else that might shed some light on this. My curiousity is now piqued because of the lack of information anywhere about this. Stay tuned for the results.

One thing I did seem to glean out of these searchs is that DOT5 doesn't seem to be worth the effort any more.

[Dick W.]

Re: Changing from DOT 5 To DOT3 brake fluid FED UP WITH AIR BUBBLES on my 67

As I posted yesterday, I'm in the process of switching back to DOT4 from DOT 5 (as part of uninstalling CSSB Inc.'s calipers and MC and replacing with new stuff from Lone Star due to continual problems with brake fluid seeping from the right front caliper hose connnection and brake fluid running down the back of the MC). My switch has more to do with the fact that I get a do over and I don't like the cumbersome, time consuming two man bleeding process that comes with DOT 5. Had I known my Motive power bleeder was not going to work with the DOT 5, I would never went down the DOT 5 road.

Switching from DOT 5 to DOT 3/4 is involved if you want to avoid any possibility of cross fluid contamination--e.g., rebuild the calipers and master cylinder to replace all the rubber seals, and flush the brake lines with denatured alcohol (which is easy with the Motive power bleeder--fill with denatured alcohol, pressurize and open the bleeders one at a time and let them drain until it's clear alcohol), and replace the rubber brake lines.

As for your current problems, I was able to bleed the system using gravity bleeding and then switching to two-man traditional method. Bothersome and time consuming, no doubt. Once bled, I didn't find the pedal feel to change after I repeatedly "worked" on right front caliper hose fitting that was weeping brake fluid, and even loosening and reinstalling the master cylinder brake lines to make sure they were not cracked and were seating properly. I didn't re-bleed every time I opened up the lines; I selectively re-bled the system when I thought I had the seeping fixed, to minimize the inconvenience of having my neighbor help me with the two man bleeding process. I did eventually conscript my neighbor to sit through the bleeding process three times over the past two months while trying to solve the "seeping" problems, and only had some relatively minor air.

I cannot imagine you have more entrapped air in the DOT 5 than I had--I used the Motive power bleeder initially which exacerbates the problem with air. I still got all that air out Also, I knew to leave the brake fluid settle in the bottles, with the cap loosened, pouring it slowly. That's about it.

FYI! if the m/c is new, the one you get will be from the same manufacturer. Only game in town

[Jim T.]

Re: Changing from DOT 5 To DOT3 brake fluid FED UP WITH AIR BUBBLES on my 67

Al did you bench bleed the master cylinder with DOT5 before you installed DOT5 in your car? When I rebuilt my 70's master cylinder I bench bled the master cylinder before installing it back on my 70. I did not have to bleed the calipers using a bench bled master cylinder. When I removed the brake lines from the master cylinder I used plugs to keep fluid in the lines and from being contaminated and open. When I installed the bench bled master cylinder I installed one brake line loose enough attached to the master cylinder to gravity feed fluid into the brake line knowing when it was leaking that the brake line and connection point had gravity fed DOT 5 and secured the brake line connection. Did the other line the same way. Result was good pedal, no bleeding of the calipers was needed and brakes tested great. I had been using DOT5 for over 20 years in the 70.
You mentioned gravity bleeding the calipers? Did you ever let the master cylinder run out of fluid during caliper bleeding? You mentioned in your post that after gravity bleeding the calipers you bled the calipers to get the air out with using the brake pedal as a pump. If you gravity bled the calipers where did the air come from? I rebuilt both front calipers on my 68 and gravity bled each caliper. Did not let the master cylinder run out of DOT5. When I had gravity flow coming from brake caliper bleeder closed it and opened the other caliper bleed valve to bleed it. With both calipers gravity bled I had good brake pedal and did not use the master cylinder to bleed more DOT5 from the rebuilt calipers. Road test was great. Have used DOT5 in the 68 for over 20 years.

[Terry M.]

Re: Changing from DOT 5 To DOT3 brake fluid FED UP WITH AIR BUBBLES on my 67

Anyone else got fed up trying to bleed all the air out of DOT 5 fluid and switched back to DOT 3? What issues will I be looking at and how do I ensure I got all the DOT 5 out of the system? Everything is new or rebuilt. 3-4 weekends is enough!!! Can the DOT 5 be blown out of the lines and calipers with air pressure or is there a better way? THANKS!!!

I too have used DOT 5 in my 1970 since the 80s. Gravity bled the system, but I had to get fluid in the lines before gravity worked. Air just does not pull the fluid along by itself.

To your question: Yes you can blow the DOT 5 out of the lines with shop air with the lines disconnected at both ends. Will you get all the DOT5 out that way? I doubt it. Someone else suggested alcohol. I don't think alcohol will cut DOT 5. That is good for the other kinds of brake fluid, but I don't know what will cut DOT 5. Try some "brake clean" (The red can) on some of it on some surface to see if that will work. Otherwise I suggest a web search or a call to the DOT 5 manufacturer to find what will dissolve it.

[Joe L.]

Re: Changing from DOT 5 To DOT3 brake fluid FED UP WITH AIR BUBBLES on my 67

One thing I did seem to glean out of these searchs is that DOT5 doesn't seem to be worth the effort any more.

Dennis-----


Among other benefits, if you install DOT 3 or 4 and ever accidentally get any on your paint (even if you are convinced that you will exercise extreme care and never get any on the paint) you will find out why installing DOT 5 is "worth the effort". I guarantee that DOT 3 or 4 will mar your paint no matter how fast you get it off.

[Paul S.]

Re: Changing from DOT 5 To DOT3 brake fluid FED UP WITH AIR BUBBLES on my 67

Al-----


Dorman #484-146 (boxed) or 13903 (carded in Help! section).

And (at least for my local NAPA) take one of the bleeder screws to NAPA, and they'll have what you need in two styles--the original and the style that has the "collar" below where the wrench fits. I had to replace one on my new calipers before I even started bleeding. The bleeder screw was so soft, it rounded off, when I snugged it up (it was not even finger tight when I took the caliper out of the box) before mounting the caliper to the car. And believe me, I didn't over tighten the thing.

As for your issue, I agree with others that it sounds like the master cylinder is your culprit.

[Paul S.]

Re: Changing from DOT 5 To DOT3 brake fluid FED UP WITH AIR BUBBLES on my 67

Dennis-----


Among other benefits, if you install DOT 3 or 4 and ever accidentally get any on your paint (even if you are convinced that you will exercise extreme care and never get any on the paint) you will find out why installing DOT 5 is "worth the effort". I guarantee that DOT 3 or 4 will mar your paint no matter how fast you get it off.

Joe, we all agree (I think) that DOT 3 or 4 if left on paint will mar it, but I can tell you from personal experience that it will not mar the paint if you wash it down quickly. In addition to my Corvette, I have owned 6 Porsches and still have one which I care about more than my 67's paint (it's PCA Club Coupe 2 of 50--the lowest number in private hands--and is painted Azurro California Blue which is a special order paint), and I regularly flush brake fluid in that car every two years. It's an ABS car so DOT 5 is not an option.

One time, the tubing on my Motive power bleeder broke and I kid you not, it hosed the entire front end of the car in DOT 4 brake fluid. I didn't panic-but I grabbed the garden hose as quickly as I could and hosed down the car where it sat in the garage, and no paint damage at all. I figure it took me at least 3 minutes to drag the hose from the back yard to the car. So my fenders, the underside of the hood (also painted base coat only/no clear coat), and the nose had brake fluid all over them for that time. And Porsche's water based paint formulations are notoriously softer than other paint.

I think it is hyperbole to guaranty that DOT 3 or 4 will mar your paint no matter how fast you get it off. The key is to see that you got brake fluid on something and rinse it off ASAP. I think most paint horror stories have some element of not realizing that brake fluid got on the paint (until you see the damage) or knowing but not rinsing it off thoroughly enough.

Also, I use ATE Type 200 DOT 4--other brands may be more caustic (or not, who knows).

[Paul S.]

Re: Changing from DOT 5 To DOT3 brake fluid FED UP WITH AIR BUBBLES on my 67

FYI! if the m/c is new, the one you get will be from the same manufacturer. Only game in town

I figured that--and yes it is a new one, but when your vendor gives you no other option than to return it for a refund and buy from other source, what's a man to do?

[Paul S.]

Re: Changing from DOT 5 To DOT3 brake fluid FED UP WITH AIR BUBBLES on my 67

I too have used DOT 5 in my 1970 since the 80s. Gravity bled the system, but I had to get fluid in the lines before gravity worked. Air just does not pull the fluid along by itself.

To your question: Yes you can blow the DOT 5 out of the lines with shop air with the lines disconnected at both ends. Will you get all the DOT5 out that way? I doubt it. Someone else suggested alcohol. I don't think alcohol will cut DOT 5. That is good for the other kinds of brake fluid, but I don't know what will cut DOT 5. Try some "brake clean" (The red can) on some of it on some surface to see if that will work. Otherwise I suggest a web search or a call to the DOT 5 manufacturer to find what will dissolve it.

I just did it with mine--I'm not a chemist but here's what I know. Alcohol appears to be lighter than the DOT 5--when it settles out in the catch jug, the alcohol's on the top and the brake fluid settles to the bottom. Also, in the master cylinder (after disconnecting the motive power bleeder), when done I could see some purple DOT 5 in the firewall side of the master cylinder chambers, and alcohol to the front. So my thinking is the alcohol under pressure should force the DOT 5 out out of the brake lines as best you can, whether it cuts it or not. That's about the best one can do, short of replacing all the hard brake lines.

[John P.]

Re: Changing from DOT 5 To DOT3 brake fluid FED UP WITH AIR BUBBLES on my 67

Hello Al, I also have used DOT 5 fluid in many corvettes over the years and have not had any problems associated with the fluid. I always use the Motive bleeder at a very low pressure ( less than 10 lbs) and constantly check the fluid level. I have had a few give me the same problem as yours and found that two of them were drawing air into the calipers while sitting for a day or so. To isolate the problem, I bled the system until the pedal was hard, then I blocked off the four hoses to the calipers with brake hose clamp tools. After finding that the pedal remained the same, I would remove one clamp at a time until I located the leaking caliper. Loose wheel bearings or excessive rotor runout can intensify the problem, however the two I encountered were in customers garages and not driven. This is a seldom seen problem, but has had me pulling out my hair a few times. Also make sure there are two bleeders on each rear caliper. I have seen them assembled with one port plugged. Good luck, John

[Joe L.]

Re: Changing from DOT 5 To DOT3 brake fluid FED UP WITH AIR BUBBLES on my 67

Joe, we all agree (I think) that DOT 3 or 4 if left on paint will mar it, but I can tell you from personal experience that it will not mar the paint if you wash it down quickly. In addition to my Corvette, I have owned 6 Porsches and still have one which I care about more than my 67's paint (it's PCA Club Coupe 2 of 50--the lowest number in private hands--and is painted Azurro California Blue which is a special order paint), and I regularly flush brake fluid in that car every two years. It's an ABS car so DOT 5 is not an option.

One time, the tubing on my Motive power bleeder broke and I kid you not, it hosed the entire front end of the car in DOT 4 brake fluid. I didn't panic-but I grabbed the garden hose as quickly as I could and hosed down the car where it sat in the garage, and no paint damage at all. I figure it took me at least 3 minutes to drag the hose from the back yard to the car. So my fenders, the underside of the hood (also painted base coat only/no clear coat), and the nose had brake fluid all over them for that time. And Porsche's water based paint formulations are notoriously softer than other paint.

I think it is hyperbole to guaranty that DOT 3 or 4 will mar your paint no matter how fast you get it off. The key is to see that you got brake fluid on something and rinse it off ASAP. I think most paint horror stories have some element of not realizing that brake fluid got on the paint (until you see the damage) or knowing but not rinsing it off thoroughly enough.

Also, I use ATE Type 200 DOT 4--other brands may be more caustic (or not, who knows).

Paul-----


I got some DOT 3 on my paint once-upon-a-time. I realized it IMMEDIATELY and washed it off within a matter of seconds. It still marred the paint----badly. I remember that incident very well and it was 38 years ago.