air in brake line?
03-08-02, 10:26 PM
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air in brake line?
okay i wish this guy had a computer.....anyway...second gen question for you guys....*well no ***** anyway...my little rx7 buddy says he has air in his brake line? is this possible? how to remove if it is?
03-08-02, 10:28 PM
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i guess you should help him
fill up the reservior, open the bleeder valves, press and hold the brakes in, tighten the bleeder valve, release brakes, repeat until satisfied.
Justin
fill up the reservior, open the bleeder valves, press and hold the brakes in, tighten the bleeder valve, release brakes, repeat until satisfied.
Justin
03-08-02, 11:01 PM
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you should do it while the car is on so that the vacuum assist works
the brake fluid reservior, under the hood in front of the vacuum assist (the big round plastic thing on the firewall in front of the driver).
on the back of the brakes there are these little nipple looking things, with a nut on them, when you loosen them, brake fluid will come out the center. when you press the brakes in it will force fluid (and the air) out of the valve, then close it off and release the brakes and it will draw in fresh fluid out of the reservior.
this is how you bleed the brakes. any more questions??
Justin
the brake fluid reservior, under the hood in front of the vacuum assist (the big round plastic thing on the firewall in front of the driver).
on the back of the brakes there are these little nipple looking things, with a nut on them, when you loosen them, brake fluid will come out the center. when you press the brakes in it will force fluid (and the air) out of the valve, then close it off and release the brakes and it will draw in fresh fluid out of the reservior.
this is how you bleed the brakes. any more questions??
Justin
03-09-02, 01:01 AM
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it's a little more then that... first you have to go in order. from fartest brake (longest line) from the master cylinder to closest. so right rear, left rear, right front, left front. (or if you have ABS, do the left front before right front.. the line is longer)
it's not too hard, but if you screw up you will have even worse working brakes, or worse yet none at all... unless you really know what you are doing leave it to someone who does. the brakes are the last thing you want to be guessing on.
but there is a nut with a nipple on it at each brake, stick a clear tube over the nipple and the other end into a bottle to catch the brake fluid. with the nut closed, have someone pump the break pedal 10-20 times. then have them press the pedal to the ground and hold it down as you open the nut and close it to let fluid come out, you can watch for air bubbles in the clear tube. do this about 5 times over for each wheel, or longer if air bubbles keep coming out. always make sure there is fluid in the resivor in the front. if that ever becomes emtpy you have to start all over again. when done the pedal should be very hard.
this is down with the engine off... you need to pull wheel off to get to the nipples. you can just do one at a time.
it's not too hard, but if you screw up you will have even worse working brakes, or worse yet none at all... unless you really know what you are doing leave it to someone who does. the brakes are the last thing you want to be guessing on.
but there is a nut with a nipple on it at each brake, stick a clear tube over the nipple and the other end into a bottle to catch the brake fluid. with the nut closed, have someone pump the break pedal 10-20 times. then have them press the pedal to the ground and hold it down as you open the nut and close it to let fluid come out, you can watch for air bubbles in the clear tube. do this about 5 times over for each wheel, or longer if air bubbles keep coming out. always make sure there is fluid in the resivor in the front. if that ever becomes emtpy you have to start all over again. when done the pedal should be very hard.
this is down with the engine off... you need to pull wheel off to get to the nipples. you can just do one at a time.
03-09-02, 01:13 AM
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not to say that doesn work but i have had better luck just opening the valve and pressing, then closing and releasing with the engine on,
but yeah do the order of wheels he suggested.
Justin
but yeah do the order of wheels he suggested.
Justin
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03-09-02, 03:24 AM
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Forgive me for calling you Jason on the other post Justin...
Speaking for myself, I would not attempt to bleed brakes with the assistance of the brake booster. I know some manuals specifically prohibit this. I believe the brake pedal going all the way to the floor as it does when bleeding the brakes has a tendancy to overstress the vacuum diaphragm in the booster... I am not saying it will happen for sure, but it is not really necessary when brake bleeding so I do not risk it.
As I have posted in earlier responses to this question, I believe the better method is to spend 25 bucks for the hand operated vacuum pump/bleeder kit. It makes short work out of brake bleeding and has numerous other uses for the mechanic as well, such as testing any vacuum operated item like the EGR valve, etc.
Speaking for myself, I would not attempt to bleed brakes with the assistance of the brake booster. I know some manuals specifically prohibit this. I believe the brake pedal going all the way to the floor as it does when bleeding the brakes has a tendancy to overstress the vacuum diaphragm in the booster... I am not saying it will happen for sure, but it is not really necessary when brake bleeding so I do not risk it.
As I have posted in earlier responses to this question, I believe the better method is to spend 25 bucks for the hand operated vacuum pump/bleeder kit. It makes short work out of brake bleeding and has numerous other uses for the mechanic as well, such as testing any vacuum operated item like the EGR valve, etc.
03-09-02, 11:44 AM
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go to an autozone, pep boys, carquest, whatever.. and you can probably find a brake bleeder kit for about twenty to thirty bucks... it's an extremely useful tool. As long as you're getting the air out of the line, might as well bleed the entire system dry then refill it.
The kit is usually just a little hand squeeze pump with a clear tube (which you attach to the bleeder valve I believe, it's been a while..) which then goes into the pump and down into the little catch tube attached to the tool.
Break all the lugs loose first, then jack the car up, if you've got 4 jackstands it makes it a lot easier.. take the wheel(s) off, starting in the order described above, longest line first, loosen the bleeder valve (on the brake caliper) and pump all the fluid out. The first one will probably fill up the catch tank at least once maybe twice or more, just empty it into an old pop bottle (and mark it brake fluid so nobody is dumb and.. yeah..) That'll suck all the fluid out of the brake fluid reservoir. As soon as that sucker is empty, tighten its bleeder valve and move on to the next one, do the same thing, will take less fluid to empty this time.. then next, then the last one.. I'd go over all of them one more time to make sure there's no stragglers sittin' around in the system.
Then from there, take your brand new (still sealed) bottle of brake fluid and open it up, having a buddy pour it in to the brake fluid reservoir (right by the big 'ol brake booster, um.. on the drivers side of the engine compartment, basically right where the brake pedal is, but in the engine bay).. fill that up to the fill line, then while he/she is doing that, go to the first line again, loosen its bleeder valve, and start pumping kinda slowly, enough to make SURE your buddy can keep filling the thing full of fluid cause if he lets it get too low, you're going to be starting all over again. Keep doing this and you'll see fluid, then wait till there's little or no air bubbles through the tube (I think its normal to see some, cause it's not an airtight fitment over the bleeder valve..) but you should see some clean brake fluid.. I'd keep pumping just a little bit to make sure there's no air pockets left in there (make sure your buddy is keeping up with filling the reservoir), then yoink the bleeder tool off the bleeder valve and tighten the bleeder valve to within whatever torque specs it is (if there even is one..) Move on to the next one and repeat the process.
If you've got, um.. I think a liter, that was enough to do both my '92 Civic and my friends '91 MR-2 when we had to change the fluid to go out on the race track, to make sure we got fresh fluid that won't boil on the race track.
Another thing to note, the quicker you can do this process the better, because brake fluid is (hydroscopic?) or whatever it is.. meaning it absorbs water, and you don't want that, because water boils a LOT easier (at a cooler temerature) than brake fluid does, and if it boils, then you've got air in your lines again, hopefully it'll just go away, back into water when it cools down again.. hopefully.
Anyhow, when you get back in the car, pump the brakes a few times till they feel solid, check the fluid again to make sure it's full, then if you have a long driveway (gravel works best), have a friend check for proper operation of brakes all four tires, you get going like 10 mph or so and lock 'em up, regardless if you have ABS or not, he/she should see at least SOME skid marks, or at least be able to observe the tires locking up and releasing with ABS, which should still leave SOME skid marks..
Check everything over once again and make sure everything's full and tight, and you should be good to go. Did I miss anything?
The kit is usually just a little hand squeeze pump with a clear tube (which you attach to the bleeder valve I believe, it's been a while..) which then goes into the pump and down into the little catch tube attached to the tool.
Break all the lugs loose first, then jack the car up, if you've got 4 jackstands it makes it a lot easier.. take the wheel(s) off, starting in the order described above, longest line first, loosen the bleeder valve (on the brake caliper) and pump all the fluid out. The first one will probably fill up the catch tank at least once maybe twice or more, just empty it into an old pop bottle (and mark it brake fluid so nobody is dumb and.. yeah..) That'll suck all the fluid out of the brake fluid reservoir. As soon as that sucker is empty, tighten its bleeder valve and move on to the next one, do the same thing, will take less fluid to empty this time.. then next, then the last one.. I'd go over all of them one more time to make sure there's no stragglers sittin' around in the system.
Then from there, take your brand new (still sealed) bottle of brake fluid and open it up, having a buddy pour it in to the brake fluid reservoir (right by the big 'ol brake booster, um.. on the drivers side of the engine compartment, basically right where the brake pedal is, but in the engine bay).. fill that up to the fill line, then while he/she is doing that, go to the first line again, loosen its bleeder valve, and start pumping kinda slowly, enough to make SURE your buddy can keep filling the thing full of fluid cause if he lets it get too low, you're going to be starting all over again. Keep doing this and you'll see fluid, then wait till there's little or no air bubbles through the tube (I think its normal to see some, cause it's not an airtight fitment over the bleeder valve..) but you should see some clean brake fluid.. I'd keep pumping just a little bit to make sure there's no air pockets left in there (make sure your buddy is keeping up with filling the reservoir), then yoink the bleeder tool off the bleeder valve and tighten the bleeder valve to within whatever torque specs it is (if there even is one..) Move on to the next one and repeat the process.
If you've got, um.. I think a liter, that was enough to do both my '92 Civic and my friends '91 MR-2 when we had to change the fluid to go out on the race track, to make sure we got fresh fluid that won't boil on the race track.
Another thing to note, the quicker you can do this process the better, because brake fluid is (hydroscopic?) or whatever it is.. meaning it absorbs water, and you don't want that, because water boils a LOT easier (at a cooler temerature) than brake fluid does, and if it boils, then you've got air in your lines again, hopefully it'll just go away, back into water when it cools down again.. hopefully.
Anyhow, when you get back in the car, pump the brakes a few times till they feel solid, check the fluid again to make sure it's full, then if you have a long driveway (gravel works best), have a friend check for proper operation of brakes all four tires, you get going like 10 mph or so and lock 'em up, regardless if you have ABS or not, he/she should see at least SOME skid marks, or at least be able to observe the tires locking up and releasing with ABS, which should still leave SOME skid marks..
Check everything over once again and make sure everything's full and tight, and you should be good to go. Did I miss anything?
Last edited by Barwick; 03-09-02 at 11:48 AM.
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