brake fluid leak

[Randall K.]

My 72 is nearing the end of repair/restoration of the HVAC and vacuum systems. I'm now making rapid progress since I've been laid off...

It's been almost 3 years since the car has run, and has been in my garage with the front wheels up on ramps for access.

After starting it up last week (no problems there!) I noticed that there was a little brake fluid leaking from the compression fitting at the far end of the steel line from the proportioning valve connecting to the flange leading to the Left Front wheel cylinder. I also thought that the brakes felt somewhat spongy compared to memory. I'm assuming that if fluid was leaking out, air was getting in, causing the spongy feeling. The master cylinder was still full.

At a minimum I know that I need to fix the leak (maybe as simple as tightening the fitting???), and then bleed the entire system.

The brake system has never been flushed in the 10 years I've had the car, and I don't have a clue as to when they were last done. I also can't say for sure what brake fluid is in the system (DOT 3, 4 or 5).

I've read a number of the posts regarding brakes, and based on the age of the fluid, assuming that I should really consider a complete drain/refill/flush of the brake system.

What else am I missing? Which fluid should I use?

Thanks
Randy

[Terry M.]

Re: brake fluid leak

Fix that leak. If the fluid is badly deteriorated you may have a rusty line. Replace the line in that case.

Looking into my Internet crystal ball I see a complete flush with fresh compatible fluid is in your future. You must determine what fluid is in your system and refill with compatible fluid. Remove some or better yet most fluid from the master cylinder. Put some in a seal-able see-through container with a like quantity of water. Shake and do not stir. Then leave set for a half hour or so. If all the fluid is milky color with little or no separation you have DOT 3,4 or 5.1. If there are two types of liquid with a clear separation you have DOT5. Refill with the same kind of fluid. For street use it doesn't matter if you buy DOT 3, 4, or 5.1 -- all will work just fine for you. Then fill the master with the right fluid and open the rear bleeder screws on one side. Watch the master cylinder fluid level and close the rear bleeder when the master fluid level gets half way or 3/4 of the way down. refill master and open the bleeder on the other side rear. You will have to get the nose of the car on the ground to do the fronts -- or get the rear up so the car is more or less level -- and repeat as above for the front. At the end you may need the help of some willing sole to pump the brake pedal for the final bleed.

Of course you could break down and buy a Motive pressure bleeder and then you would not have to level the car. There are several threads ont he subject of bleeding brakes in the archives. Page down to the bottom of this page for 5 links to similarly titled threads. Now that the Moderators have put this feature back on the board every thread gets 5 free effortless searches.

[Joe L.]

Re: brake fluid leak

At a minimum I know that I need to fix the leak (maybe as simple as tightening the fitting???), and then bleed the entire system.

Randy------


Most likely, all you will need to do is to tighten the fitting. However, if that does not solve it, you will need to remove the brake line and inspect the flared end for cracks. A crack in the flared end will cause a leak like you describe and such cracks are not uncommon. Even a TINY crack will cause a leak because of the pressure the system develops when the brakes are applied. If a crack is found, you will need to replace the brake line.

All brake line ends are double-flared. You must maintain this type of flare and if you buy a reproduction brake line, it will have a double flare.

[Patrick H.]

Re: brake fluid leak

Randy------


Most likely, all you will need to do is to tighten the fitting. However, if that does not solve it, you will need to remove the brake line and inspect the flared end for cracks.

If you take it off, you'll probably replace it. Odds are there is a bit of corrosion at the end and you'll not want to reinstall it.

Patrick

[Paul O.]

Re: brake fluid leak

If you take it off, you'll probably replace it. Odds are there is a bit of corrosion at the end and you'll not want to reinstall it.

Patrick

Patrick

I wonder how you know about that corrosion issue have you seen this before.


Paul 18046

[Patrick H.]

Re: brake fluid leak

Patrick

I wonder how you know about that corrosion issue have you seen this before.


Paul 18046

In Michigan?

[Terry M.]

Re: brake fluid leak

What, and NOT in Ohio??

[Randall K.]

Re: brake fluid leak

Thank you all for the advice. Fortunately, the car is running, so I do have all 4 wheels on the ground. I also have a vacuum hand pump that should speed up the bleeding process.

Randy

[Paul O.]

Re: brake fluid leak

What, and NOT in Ohio??

Terry

Its all about proper storage.

Paul 18046

[Terry M.]

Re: brake fluid leak

That Is so true Paul. One of the nicest chassis I ever saw was on a 1300 mile Michigan car. I was told it had been stored in a barn with a lot of ventilation betweent he boards on the walls. It was stunning. I think we judged it at one time. 1970, Mulsanne Blue white top convertible 390 HP.