DOT 5 experts please read -

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66dartgt

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This isnt an A body but it is a mope. 82 dippy. We decided to put DOT 5 in my son's car on which we rebuilt the whole system.

We replaced calipers, hoses, wheel cylinders, and master cylinder. We blew the lines out and then installed the bench bled master and allowed it to gravity bleed for an hour or so before hooking the hardlines to the hoses. The master cylinder did not go dry. We then bled the system using the time honored manually bled procedure RR, LR, RF, LF. We thought we had it bled out as there were no big bubbles coming out, only very tiny pin point sized bubbles.

Go to drive the car, well the pedal is real low, we drive it around the block and the brake warning light comes on. Ugh.

That was last week. This week we put it on jack stands and go thru the whole procedure again. Maybe a little better now, the brake warning light is staying off. But now we are getting frequent moderate sized bubbles from each wheel.

So, I do an internet search and find some people recommending heating the fluid as it traps air. So, we do this, we do see a fair amount of small bubbles form and then break, heated to 212 F. After that - well - more or less the same result, moderate sized bubbles that wont go away, even after pumping quarts of fluid thru this thing.

What gives ? Ive used silicone fluid before and had issues with tiny bubbles but geez this is driving us crazy.

I can't think of anything we missed. We've tightened and rechecked all the threaded connections - nothing seems to have helped much.

I am thinking this might be cold weather making the problem worse ? It was below 30-40F in the garage today.

any thoughts are appreciated.
 
I have DOT 5 in everything I own and haven't had any problems. The Warning light could have been because the Prop valve wasn't centered after bleeding. There is a procedure to center it in the FSM. As for air, naturally DOT5 is more prone to trap air so no shaking of the can, etc, before using (for a couple of days). Another trick I've learned is to bleed slowly. I used to be one of these guys to pump the heck out of it, hold it down and open the bleeder quickly and then close when the pedal is on the floor. DOT5 doesn't like that method. Better to pump and hold down and slowly open the bleeder, bleed a little and close it before the pedal hits the floor. Reason is, when the pedal bottoms out, the plunger in the MC actually rebounds a slight amount and could be drawing air in before you close the bleeder. I went and got a set or Russel's speed-bleeders and put on mine. Makes bleeding a one man job.

Larry
 
hearold hit her on the head....thats the way i do it at work...remember that you replaced the whole system...alot of air will be in it....
 
you will need 2 people...im assuming you know this....tell them to pump it up while the bleeders are closed....then tell them to hold and crack the bleeders slightly....and close them before the pedal goes all the way down...like hearold said...
 
69 Valiant Kid said:
you will need 2 people...im assuming you know this....tell them to pump it up while the bleeders are closed....then tell them to hold and crack the bleeders slightly....and close them before the pedal goes all the way down...like hearold said...
Click to expand...


yeah, make sure the guy on the brake pedal know what he is doing. most auto parts stores sell a hand pump vacuum kit to do it yourself. worked good on a motorcycle for me but haven't tried it on a car yet.
 
Appreciate the replies. We'll give it another go this weekend. car is still on blocks so what the heck. Besides we cant drive it until the brakes are working - right?

We are using two people, my son is running the pedal and I the bleeders. I think we'll change it around, me on the pedal - him on the bleeder and try it the way you folks suggest, closing the bleeder before bottoming the pedal.

Wish us luck -

If anyone else has comments please chime in.

Thanks !
 
i doubt its the fluid... how did you blead it? if you did the pump the pedal thing then you may made a ton of tiny air bubles into the system.. you have to gavity blead at first, then after you have pedal like that you can pump very slowly and blead like that.. especially if everything is new.
 
This is one thing I'm still working on with the Valiant. Yes I'm using Dot 5 also, I'm not an expert though. I'm still getting those little fine air bubbles. I also put teflon tape around the bleeder that helped a bunch. I haven't drove my car yet, but it has a half a pedal at the moment. Soon as the weather gets warmer I'm getting back on that.

From reading what abodyjoe wrote I'm going try that.
 
your good if your not driving it yet.. let it sit and hopefully the air will migrate to one spot... when i did my entire system over thats how i did it because of advice from a guy that i listen too when he talks.. this guy is good... after gravity bleading i pumped the pedal very slow and i had a great feeling pedal and two year later still have a great pedal..
 
Preasure bleed it! It's the only way to go with silicon fluid.I have in everything I own and have been using it for 15 years now.It's well worth the initial cost and once you bleed it out right you're done for a long long time, and it won't eat that nice paint on the firewall like the cheapo dot 3 crap
 
update -

We bled the brakes again today using a pressure pot. The rears bled out fine, the fronts didnt work at all, with the pressure bleeder.

There is a low pressure valve on the prop set up which you are supposed to pull out, a little metal tit, but when it was pulled out no flow from the fronts. So we bled it slow with a block of wood under the pedal for the fronts.

Worked fine, car has brakes out the wazoo now.

Wohoo !
 
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