Changed brake fluid - air in the lines?
#1
Changed brake fluid - air in the lines?
I just changed my brake fluid with my power bleeder.
Before I added new fluid I intended to get the reservoir just low enough not to get air in the system. Sure enough I pumped some air into the system...
I "flushed" all old fluid and hopefully all air with one liter of Super Blue and the only air bubbles I saw was on the first right rear caliper.
on the test drive the pedal seemed a bit soft initially, but then seemed normal. I seated the new pgid grey pads as suggested with 15 cycles and the whole system got pretty hot and seemed fine.
Since I have a track day coming up Saturday I am a bit worried that I somehow still have some air in there... I did not bleed the clutch.
Any suggestions?
Before I added new fluid I intended to get the reservoir just low enough not to get air in the system. Sure enough I pumped some air into the system...
I "flushed" all old fluid and hopefully all air with one liter of Super Blue and the only air bubbles I saw was on the first right rear caliper.
on the test drive the pedal seemed a bit soft initially, but then seemed normal. I seated the new pgid grey pads as suggested with 15 cycles and the whole system got pretty hot and seemed fine.
Since I have a track day coming up Saturday I am a bit worried that I somehow still have some air in there... I did not bleed the clutch.
Any suggestions?
#4
the power bleeder shouldnt be used for a break bleed only for the reasons you have seen. I used it to change the fuid, and then as a final step, use the traditional method of push the pedal and open the bleeder screw.
I tried to use the power bleeder at the track once, and it failed as you have seen.
MK
I tried to use the power bleeder at the track once, and it failed as you have seen.
MK
Originally Posted by Sab
I just changed my brake fluid with my power bleeder.
Before I added new fluid I intended to get the reservoir just low enough not to get air in the system. Sure enough I pumped some air into the system...
I "flushed" all old fluid and hopefully all air with one liter of Super Blue and the only air bubbles I saw was on the first right rear caliper.
on the test drive the pedal seemed a bit soft initially, but then seemed normal. I seated the new pgid grey pads as suggested with 15 cycles and the whole system got pretty hot and seemed fine.
Since I have a track day coming up Saturday I am a bit worried that I somehow still have some air in there... I did not bleed the clutch.
Any suggestions?
Before I added new fluid I intended to get the reservoir just low enough not to get air in the system. Sure enough I pumped some air into the system...
I "flushed" all old fluid and hopefully all air with one liter of Super Blue and the only air bubbles I saw was on the first right rear caliper.
on the test drive the pedal seemed a bit soft initially, but then seemed normal. I seated the new pgid grey pads as suggested with 15 cycles and the whole system got pretty hot and seemed fine.
Since I have a track day coming up Saturday I am a bit worried that I somehow still have some air in there... I did not bleed the clutch.
Any suggestions?
#5
You guys must have a different power bleeder to me. (I have a Gunsons Eezi bleeder) It pressurises the cars reservoir with fluid from it's own air pressurised brake fluid reservoir. So unless you use more than 2pints to bleed the brakes you don't end up with air pumped into the system.
A much bigger pressure bleeder can be made using a redundant 928 brake reservoir cap drilled to fit a hose barb connected to the delivery hose of a garden sprayer.
Never pumped air into the brake system on the 928s.
A much bigger pressure bleeder can be made using a redundant 928 brake reservoir cap drilled to fit a hose barb connected to the delivery hose of a garden sprayer.
Never pumped air into the brake system on the 928s.
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#9
Supercharged
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I too have not had very good results using the power bleeder for bleeding. It's good for changing fluid, but for bleeding, I use one of the "One man bleeder" kits you can buy for $4 at any auto parts store. Works like a charm.
#10
Sound like your soft pedal was due to the fresh pads. If the pedal is now firm, then you did get most of the air out.
Bring the bleeder and a qt. of fluid to the track just in case.
Bring the bleeder and a qt. of fluid to the track just in case.
#11
I just got tired of having to clean to Power Bleeder after use. So, I went to SpeedBleeders and just go a wheel at a time, keeping a watchful eye on the reservoir to make sure it doesn't get too low. I love the SpeedBleeders.
#12
Sab,
If you are concerned about having air in the system:
1) With the engine off, press and release the brake pedal ten times.
2) Release the pedal, and wait ten seconds.
3) Press the brake pedal firmly. What you have now is pure hydraulics - no boost. If the pedal is high and firm, there is no air in the system. If the pedal is spongy, you have air in the system, soft hoses, etc.
4) Press and hold the brake pedal with moderate pressure as you crank the engine. The pedal should get softer and fall somewhat. This shows that the power boost is working.
5) Release the pedal, wait a few seconds and push the pedal with moderate pressure. This is the normal feel and distance for your system.
6) Drive the car, including some sharp turns. Press the pedal with moderate pressure. If the pedal goes noticeably further down, you have warped rotors or loose wheel bearings knocking the pads back in the calipers.
If you are concerned about having air in the system:
1) With the engine off, press and release the brake pedal ten times.
2) Release the pedal, and wait ten seconds.
3) Press the brake pedal firmly. What you have now is pure hydraulics - no boost. If the pedal is high and firm, there is no air in the system. If the pedal is spongy, you have air in the system, soft hoses, etc.
4) Press and hold the brake pedal with moderate pressure as you crank the engine. The pedal should get softer and fall somewhat. This shows that the power boost is working.
5) Release the pedal, wait a few seconds and push the pedal with moderate pressure. This is the normal feel and distance for your system.
6) Drive the car, including some sharp turns. Press the pedal with moderate pressure. If the pedal goes noticeably further down, you have warped rotors or loose wheel bearings knocking the pads back in the calipers.
#14
Chronic Tool Dropper
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I fab'd the garden sprayer version that JonSE mentions. Works like a champ, never had a problem, used it on may cars including guests' cars at 'fluid flush' clinics here. I can scrounge the instructions for making it, although the Motiv unit is not much more expensive and already bulit. I can put a gallon of fluid in the one I made, though that car barely needs more than a quart.
For ABS cars especially, it's somewhat important to avoid getting air caught in the ABS pump and valve I suspect.
I recommend in my bleeder use instructions that you purge the air out of the line between the bleeder and the cap before you attach the cap to the reservoir. If you decide to drain the reservoir of all the old fluid, you really want to fill the reservoir with new fluid directly, before you put the bleeder cap on there and start pushing, else air may go in before the fluid from the tank fills the reservoir.
Ed-- Got tired of cleaning the power bleeder? Huh? What's to clean? Dump any remaining fluid out with your old stuff, close the tank and put the thing away. It's cleaned. One of many 'last things' you want to have in the tank is water, so there's not a lot of cleaning to do really. I pour a little fresh fluid in it before each use, slosh it around in the tank and pour it out before filling the tank with new fluid at the next use. The toughest part of putting the bleeder stuff away is storing the little hoses and the adapter cap in a ziplock bag and putting it all in the box on the shelf.
In my opinion, the power bleeder kicks butt over the manual press-and-squirt method. Over the years, I have managed to accidentally pump the reservoir dry a few times using the manual method. It takes two people, and you have to train your pusher to stop a little off the floor and acll out the pedal positions so you know when and which way to turn the bleeder screws. Contrast with the power bleeder: One person, set it up on the MC, then just walk around from wheel to wheel, opening the valve until fluid flows clear then closing. It just couldn't be much easier.
For ABS cars especially, it's somewhat important to avoid getting air caught in the ABS pump and valve I suspect.
I recommend in my bleeder use instructions that you purge the air out of the line between the bleeder and the cap before you attach the cap to the reservoir. If you decide to drain the reservoir of all the old fluid, you really want to fill the reservoir with new fluid directly, before you put the bleeder cap on there and start pushing, else air may go in before the fluid from the tank fills the reservoir.
Ed-- Got tired of cleaning the power bleeder? Huh? What's to clean? Dump any remaining fluid out with your old stuff, close the tank and put the thing away. It's cleaned. One of many 'last things' you want to have in the tank is water, so there's not a lot of cleaning to do really. I pour a little fresh fluid in it before each use, slosh it around in the tank and pour it out before filling the tank with new fluid at the next use. The toughest part of putting the bleeder stuff away is storing the little hoses and the adapter cap in a ziplock bag and putting it all in the box on the shelf.
In my opinion, the power bleeder kicks butt over the manual press-and-squirt method. Over the years, I have managed to accidentally pump the reservoir dry a few times using the manual method. It takes two people, and you have to train your pusher to stop a little off the floor and acll out the pedal positions so you know when and which way to turn the bleeder screws. Contrast with the power bleeder: One person, set it up on the MC, then just walk around from wheel to wheel, opening the valve until fluid flows clear then closing. It just couldn't be much easier.
#15
I'm another person that has not had good results from a power bleeder (Motive). At first I thought it was my unfamiliarity with power bleeding or just didn’t have the “hang” of it.
I was going to try and rebleed this weekend with the power bleeder to see if I could get it to work; however, after reading this thread I think I will do it without the bleeder.
I was going to try and rebleed this weekend with the power bleeder to see if I could get it to work; however, after reading this thread I think I will do it without the bleeder.