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zoltanb

strange brake fluid leak

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I took out the 89 for 100 mile drive out to the West Virginia mountains for a cruise in preparation of South Bend. The car has been in the garage for about 3 weeks since last driven. On the way home I got stuck at a 5 minute traffic light with my foot on the brake for all 5 minutes and as I was taking off brake and abs lights come on and a warning "low Brake Pressure". Drove home in another 10 minutes with the warning lights on. When I get home the wife stops me before I can pull into the garage and says car left a puddle on the floor. Turns out it was a good sized puddle of brake fluid. Cleaned up the mess and about 10 minutes later start the car to pull in and lights are off no warnings. I checked the fluids and all were fine the brake reservoir had some fluid around the cap and at the midriff. pulled the connector off the pressure switch no leaks. Could there be back pressure causing the fluid back thru the cap? It was not overfilled and was recently flushed. Any ideas or suggestions on what to check? Thanks Zoltan

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WHERE on the floor? I assume you mean the garage floor as opposed to the car floor...Typical east coast brake line rust is usually around the LR wheel well. Under the Teves unit, well could be a lot of possible leaks.

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Hello Harry, Yes the garage floor, brake lines are fine, the reservoir did not appear to be missing any fluid, only took about 2 table spoon full to bring it up to the mark. I am also fortunate to have a car from Texas with no rust.

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Thanks Ronnie, Yes your tutorials are always checked as well as the FSM. Could the accumulator be going bad?

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I don't have an answer for you. I don't understand the system enough to give advice.

I've often wondered though, what happens to the compressed gas inside the accumulator ball when the diaphragm fails. The diaphragm acts as a sort of check valve/barrier when it is intact. When the brake fluid is reduce to a pressure below that of the compressed gas, the diaphragm follows the fluid down until it hits the bottom of the ball where it stops at the balls opening at the bottom. This is what keeps the gas from escaping into the system. But what exactly happens when the diaphragm splits open and there's nothing in the way to keep the gas from leaving the ball and entering the system? If you also had a small, barely noticeable leak in the system somewhere and the car sat with the gas pressure now able to push on the fluid... well then... what?

John F.

Edited by Machiner 55 (see edit history)

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Sounds to me like your accumulator is weak, and fluid was topped off after flush while accumulator was pressurized, and excess was forced out the cap when accumulator depressurized as it sat in the garage.

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...

1. When I get home the wife stops me before I can pull into the garage and says car left a puddle on the floor. Turns out it was a good sized puddle of brake fluid. Cleaned up the mess and about 10 minutes later start the car to pull in and lights are off no warnings.

2. I checked the fluids and all were fine the brake reservoir had some fluid around the cap and at the midriff. pulled the connector off the pressure switch no leaks. Could there be back pressure causing the fluid back thru the cap? It was not overfilled and was recently flushed. Any ideas or suggestions on what to check? Thanks Zoltan

I'm in agreement with Mc_. I don't want to sound argumentative but you would have to admit that the two statements highlighted above are contradictory.

It would be hard to leave a large puddle of brake fluid in the garage floor when you leave and then when you get home a check of the fluid shows the level is up to the full line. However, if you are sure the reservoir was filled properly as outlined in the instructions on my website I won't dispute that. But, the symptoms of fluid running out of the cap, down the side of the reservoir and puddling up on the ground are consistent with the reservoir being filled up to the full mark without depressurizing the system.

It might be possible for the bladder in the accumulator ruptured and the release of the gas expelled fluid out of the reservoir. If that was what happened the accumulator is bad and the red warning light should come on(along with the yellow ABS light) each time you press the brake pedal. There is an accumulator test on my website that should verify if the accumulator is bad.

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Should I wait till the accumulator dies or just replace it? Ronnies test says it recovers in time. I have the same question as Machiner 55? Where does the gas go?

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Ronnie, The lights went out after sitting for 10 min or so. So I guess it is new accumulator time.

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I agree with Ronnie.

Another idea is that if you changed brake pads since your last flush there would be excess fluid as well.

At any rate the think with leaks is that they are not selective, either you have one or you don't. Most likely an overfill situation.

When you added your two tablespoons did you pump the brakes 25+ times then add?

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A new accumulator certainly wouldn't hurt but if yours passed the test on my website and the red brake warning light isn't coming on regularly I'm not convinced at this point that the accumulator was the cause of the problems you describe. I would wait until you have more information about what would cause the problem before ordering a new one. Maybe someone else has some ideas about what the caused your problem.

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Dave no I did not bleed it down, did not think it would make a difference. Brake pads were done months before the flush. I think I will bring an accumulator along to South Bend just in case.

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Dave no I did not bleed it down, did not think it would make a difference. Brake pads were done months before the flush. I think I will bring an accumulator along to South Bend just in case.

I'd go ahead and buy and put it on before heading to SB just to make sure you're not putting unnecessary wear on the brake pump.

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How hot was it that day and how hard were you on the brakes while you were descending the mountains. Are you running stock thermostat and cooling fans?

First time I ever encountered the red light coming on I was stuck in bumper to bumper traffic with foot on pedal more than off on a very hot day. Engine temp was at point that stock high speed fans came on so it was hot under that hood. Pump and accumulator couldn't keep up with needed pressure and red light kept coming on until I could break free of the jam and get some air flow thru the radiator to cool things down, and keep my foot off the pedal.

Replaced the accumulator and altered the high speed fans to come on sooner and haven't had that problem again.

As to where the gas goes, it doesn't leave the bladder in the accumulator unless that ruptures. If the bladder ruptures, the gas would tend to still stay put in the metal ball. That's why the ball is up and the inlet is down. Same principle as the diving bell. If there is sufficient volume at the system pressure, some of it might be expelled back into the system thru the inlet, where it could go thru a valve in the valve body if the pedal is depressed, or back up thru the pump and possibly a little would make its way into the reservoir, but there's a lot of fluid volume that would have to be displaced first for any to make that journey.

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As I see it, if the bladder leaks, the nitrogen (that's what's in the ball, right) will blow into the hydraulic line and back to the reservoir.

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It was 95+ had the ac full blast engine temp 213 and the fans were cycling but mostly on. My calipers are all about 2yrs old not frozen so the fluid did not boil. I am going to put the new accumulator on tomorrow and do the same drive. I think I need to get my fans reprogrammed. How did you alter them? Is there a quicker way than sending it out?

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Right now I'm probably the last person to give any advice on Teves brake problems (just take a look at my new thread as an example) but, you might want to check the resevoir to pump supply hose. Mine started to leak and would only leak when brake pump/motor was running, still doesn't sound right but it wouldn't leave a puddle when parked but it dripped when motor/pump would kick on.

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If you give the system "The Brake Tests" you will know if the Accumulator is bad ! I'd do so before replacing.

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Keep in mind that if the accumulator is bad, when you hit the brakes, the pressure drops, rel light comes on, turns off the ABS and all four wheels will lock if pushing hard. (Wonder if that is why ABS was standard, Reatta really needs it).

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For grins you might check the moisture content of your brake fluid.

There was certainly enough heat in the engine compartment if you have a high moisture content in the fluid.

If you have a DMM you can do an easy quick and dirty check.

Set meter to DC volts, 2 volt scale.

Remove cap from brake fluid reservoir.

Hold ground probe to a good ground point like block or top of metal intake.

Immerse positive probe into center of fluid in reservoir.

Watch reading for awhile to get a stable value.

If reading is -0.30 or higher there is too much moisture in fluid.

post-55241-143141996578_thumb.jpg

Edited by Mc_Reatta (see edit history)

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After doing the accumulator test I found out that mine was on the way out, replaced it with a spare and all seems well. Do accumulators have a shelf life? I have 1 more that has been sitting for close to 2 yrs. Mc Reatta that's a great test. I keep to a 2 yr schedule of replacing brake fluid and antifreeze. I am not going to drive the 89 till next weekend, I will check to see if I have more leaks.

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We have discussed the condition of "new" accumulators on this forum before.

There is no discernible date code on the packaging or accumulator itself, so the debate over whether you could buy a recently manufactured one or just new old stock ones that were made years ago could not be answered.

Only conclusion was it seemed "new" ones did not yield as many pedal pushes before light comes on as new ones yielded years back.

Because nitrogen's molecular size is fairly large as gases go, it tends to leak out of confinement more slowly. That's why purists like to inflate their tires with it. But over enough time, leak it will, so believe there would be a shelf life to an accumulator, but what it might be is unknown.

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