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      10-02-2010, 04:46 PM   #1
Eurotrash8
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Help...Leak in brake system?

I am flushing out my brakes now with the vacuum method. I started by sucking the old fluid out with my vacuum extractor, topped it up and began on the first brake. I attached the vacuum to the nipple on the caliper loosened it a 1/4 turn and started the pump with 3-5 pumps to get pressure.

While it is sucking the fluid there is a constant stream of fluid and air bubbles as I'm keeping the fluid above the min line and have gone through a 500ml bottle for one brake so far.

Could there be a leak in the brake system? The fluid level has stayed the same for over a year now though

Thx for any help or suggestions.
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      10-02-2010, 06:51 PM   #2
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LOL. I am not being mean. The bubbles of air sneak in between the tube you attached to the nipple and the nipple. I assume they are tiny bubbles. Normal, and stop wasting brake fluid. At least by now you flushed the system, and all you need to do is bleed the remaining calipers.
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      10-02-2010, 09:13 PM   #3
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No offense taken.. Apologies if this is a stupid questions for most but its my first time using a vacuum system as I usually use the 2 person method.

They are not really little bubbles but more like pulses of air, fluid, air, fluid...

I seen videos of guys using the vacuum method and there are big streams of air bubbles, then tiny ones, and eventually nice stream of just fluid.


TIA.
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      10-03-2010, 12:50 AM   #4
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Quote:
Originally Posted by Eurotrash8 View Post
Could there be a leak in the brake system?
Perfectly normal when using vacuum buddy; no worries. Just don't let fluid level drop much below the min mark, or you risk sucking air. And don't open the valves more than about 1/4 of the way. It's not critical, but you should start with the farthest valve, and finish with the closest, which means RR, LR, RF, LF. And don't forget the clutch if you have a 6MT.

I prefer vacuum than anything else, and it's a one-man job, but it's a matter of preference. The braking system is designed to be pressurized from the master cylinder down, not from the reservoir, so I'll never use a pressure bleeder myself. And will never use those 'speed bleeders' either . Good luck.
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      10-03-2010, 01:28 AM   #5
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Quote:
Originally Posted by TrackRat View Post
I personally do not like the vacuum method even though I have used it in the past.

OP- If you drained all of the fluid from the system via vacuum vs. just draining what was in the fluid reservoir, then you could have a lot of air in the system. If you just drained the fluid reservoir, topped up and continued bleeding, then I suspect that the air you are seeing is coming in around the threads on the slightly open bleeder screw.

Nooo... All I did was open up the reservoir and suck out all the old fluid and once done I topped it up with new stuff. So I would assume that the air bubbles was from the bleeder screws/hose to nipple area.

The part I still dont get is how do you know if all the air is out of the lines for that caliper if the vacuum is still flowing tiny air bubbles?


I'd try bleeding the other wheels to see if the fluid comes out clean. Then I'd check the pedal to see if you have a solid pedal or a mushy pedal. If the pedal is firm you should be fine. I doubt you created a leak other than a tiny air leak at the bleeder screw/hose allowing air to enter.

FWIW, when you get a few extra bucks buy a pressure bleeder. It will last a lifetime and save you tons of grief and brake fluid. It will be the best $55. you ever spend on tools.

God Dammit I just bought this vacuum extractor.


http://store.motiveproducts.com/euro...-0100-p34.aspx
Quote:
Originally Posted by elp_jc View Post
Perfectly normal when using vacuum buddy; no worries. Just don't let fluid level drop much below the min mark, or you risk sucking air. And don't open the valves more than about 1/4 of the way. It's not critical, but you should start with the farthest valve, and finish with the closest, which means RR, LR, RF, LF. And don't forget the clutch if you have a 6MT.

Yeah, like I alluded to above I just sucked out old fluid from reservoir and retopped with new stuff and then began bleeding WITHOUT opening valve more than 1/4 turn.

Maybe I can get your take or experience on the air bubbles from the nipple/bleeder screw since you are using vacuum as well.

How would I know when all the air is out of that particular line if its constantly emitting tiny air bubbles?


I prefer vacuum than anything else, and it's a one-man job, but it's a matter of preference. The braking system is designed to be pressurized from the master cylinder down, not from the reservoir, so I'll never use a pressure bleeder myself. And will never use those 'speed bleeders' either . Good luck.
Vacuum method seems sooo fast, easy and clean compared to other methods but this one issue has me questioning the effeciency.
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      10-03-2010, 12:40 PM   #6
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Don't worry about those bubbles man, or you'll go crazy. The effect is the same when you're trying to suck the last drops from a glass with a straw. And the sound is similar too, but more muted. ANY pressure method (positive or negative -a.k.a. vacuum) is going to create bubbles as fluid goes thru the nipple, creating turbulence. And that includes pushing the brake pedal... unless you do it VERY slowly to avoid gushing fluid through the valve, and with the hose pointing up (and going over the tire, like I always do). That's the way I do it on my motorcycles because it only takes a few strokes, and I can do it by myself.

Since you're not supposed to store an open container of brake fluid, just finish off the bottle (1L) and you won't have to worry about any bubbles . Don't expect the brakes to feel any better if you had no air inside, but they shouldn't feel any worse either. Check that brake pedal is hard, then go for a drive after you're done.

You don't have to worry about any bubbles unless you replaced brake lines or suck air while bleeding. Then you have to make sure there're no bubbles, and sometimes that requires a reverse fill. And if pedal is still spongy, then you need dealer to activate the ABS/DSC pump (and also push caliper pistons all the way in). But you don't have to worry about that now . Good luck man.
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      10-03-2010, 04:35 PM   #7
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Thanks for your help and wealth of knowledge Elp_jc, as well as TrackRat and 1morelap.
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      10-05-2010, 08:11 AM   #8
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Quote:
Originally Posted by TrackRat View Post
I personally do not like the vacuum method even though I have used it in the past.

OP- If you drained all of the fluid from the system via vacuum vs. just draining what was in the fluid reservoir, then you could have a lot of air in the system. If you just drained the fluid reservoir, topped up and continued bleeding, then I suspect that the air you are seeing is coming in around the threads on the slightly open bleeder screw.

I'd try bleeding the other wheels to see if the fluid comes out clean. Then I'd check the pedal to see if you have a solid pedal or a mushy pedal. If the pedal is firm you should be fine. I doubt you created a leak other than a tiny air leak at the bleeder screw/hose allowing air to enter.

FWIW, when you get a few extra bucks buy a pressure bleeder. It will last a lifetime and save you tons of grief and brake fluid. It will be the best $55. you ever spend on tools.

http://store.motiveproducts.com/euro...-0100-p34.aspx
+1 on the Motive Product. I've done both the vacuum(attached to the air compressor) and pressure bleed. I prefer the pressure bleed, but rather than fill the pressure bleeder with fluid, I suck out the old fluid in the reservoir first, then fill the reservoir with SRF, then attach the pressure bleeder (just cleaner in my opinion).

Quote:
Originally Posted by elp_jc View Post
The braking system is designed to be pressurized from the master cylinder down, not from the reservoir, so I'll never use a pressure bleeder myself. And will never use those 'speed bleeders' either . Good luck.
Good point, but I've never had any issues with a pressure bleed.
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