Brake fluid exchange advice

Discussion in 'Troubleshooting & Diagnosis' started by severum17, Mar 5, 2017.

  1. severum17

    severum17 New Member

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    So, I am the original owner of a 77 Z. Still has the original brake fluid. Yeah, I know, but it still stops and functions fine. This has been bothering me and I know it needs to be flushed but I dont want to open a can of worms. If I flush it with fresh fluid am I looking for issues with seals and brake cylinders? What DOT should I use. It stops now and I dont want to end up replacing the calipers and cylinders. Thoughts?
    Thanks MikeM
     
    Last edited: Mar 5, 2017
  2. Gary S

    Gary S Administrator Lifetime Gold Member

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    Use the recommended fluid. Don't change to anything else. New fluid shouldn't cause any issues with seals or cylinders. It should extend the life of them as it won't have debris in it like the old fluid might have already.
     
  3. Bandit723

    Bandit723 Veteran Member

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    More that likely you are using DOT 3 fluid but i would test it first. Even with a flush and put in the wrong fluid, you could cause issues if you do not get it all out.

    DOT 3, 4, and 5.1 can be mixed if necessary, according to the instructions on the cans. The temperature range is higher as it progresses from DOT 3 to 4 to 5.1

    DOT 5 and DOT 5.1 are not the same.

    DOT 5 is a silicone based fluid, and DOT 3, 4, and 5.1 are glycol? based.

    don't guess.... this is how to check:-

    Essentially, there are two types. The first one is regular auto brake fluid. The second type is Silicone-based brake fluid.

    You can not mix the two types of fluid (well, you can, but you will end up with a jelly-like mess).

    You need to find out which you have already in the system. Here's how:-

    1. Get a dropper (an eye or ear-dropper) and withdraw some fluid from the master cylinder.
    2. Put it into a glass jar and then add some clean water to the fluid.
    3. Now put the lid on the jar and shake it well.
    4. Let it stand for a few minutes.
    5. If the water and the fluid have mixed thoroughly and can not be separately identified, then you have regular auto brake fluid.
    6. However, if the water and the fluid have not mixed, or have formed blobs or layers, then the fluid is Silicone.

    That's all there is to it. Lots of people think that you can recognise which is which by looking at the colour of the fluid, or by its odor. Don't risk it. Use the test outlined above. It's already been said that DOT 5 is not always purple, or that it can change color after time to a yellow that looks like DOT 3.
     
  4. BonzoHansen

    BonzoHansen Administrator Lifetime Gold Member

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    Empty the master using a siphon or even a turkey baster. Fill with clean dot3. I wouldn't mind wasting fluid, i'd gravity bleed each wheel until the master is low, close the bleeder, refill, next wheel. Rr,lr,rf,lf. You can always pedal bleed each wheel afterwards if you want.

    If you run into any issues with seals then you were gonna have issues anyway. I cant imagine 40 year old wheel cylinders working well or even lasting that long. You are on borrowed time imo.
     
  5. severum17

    severum17 New Member

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    silo.jpg [​IMG]
    Believe it or not, they still work fine and I know what fluid is in it. Its factory. I bought it new and its never been changed. I figure now is the time. Will I get dinged for not having OE brake fluid? Its time to do some basic maintenance on this original car.
     
  6. BonzoHansen

    BonzoHansen Administrator Lifetime Gold Member

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    Dinged? You mean for judging? No. brake fluid is not date coded lol
     
  7. severum17

    severum17 New Member

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    Shoulda been an LOL for my statement. Not worried about date coding.
     
  8. Bandit723

    Bandit723 Veteran Member

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    Totally missed the original brake fluid part. If it was not and did not know you do now have a way to test it...
     
  9. COPO

    COPO Veteran Member Lifetime Gold Member

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    I use Dot 3 in my 70 Z28 and I'm sure it was used in 77 unless they upped to Dot 4.

    [​IMG]

    [​IMG]
     
  10. Gary S

    Gary S Administrator Lifetime Gold Member

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    Your owner's manual should tell you what fluids to use on the car.
     

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