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BrakesDiscussions about the brake system in your vehicle and brake products.
This is a discussion thread titled "if the bleeder valve is opened is bleeding required?", within the Brakes forum, part of the Technical & Vehicle Assistance Forums category.
if the bleeder valve is opened is bleeding required?
Hi,
I was wondering if I open the bleeder valve on the calipers to compress the piston, will the system have to be blead or will no air get in from compressing them? I am sure it would be the best thing to bleed them, but is it required?
Re: if the bleeder valve is opened is bleeding required?
Quote:
Originally Posted by gquenstedt
Hi,
I was wondering if I open the bleeder valve on the calipers to compress the piston, will the system have to be blead or will no air get in from compressing them? I am sure it would be the best thing to bleed them, but is it required?
Thanks
You don't need to open the bleed valve to compress the pistons. If you've topped off the fluid reservoir (which you're not supposed to do, or the fluid level indicator becomes useless as a secondary wear indicator), use a turkey baster to remove some fluid before you press the pistons back in.
If you do open the bleed valve without internal pressure, definitely bleed just in case air was drawn in.
If you made it to a pad change and haven't already flushed the fluid, now is probably as good a time as any.
Re: if the bleeder valve is opened is bleeding required?
Sean is exactley right except for one lttle thing. If you have ABS it is better to open the bleeders when pushing the pistons back in. The reason why they say this is, small bits of sediment can end up in the calipers and if you push this stuff through the ABS unit these small pieces can get stuck in the small ports in the ABS or in the dump valve seats This can cause the ABS to fail.
Though I have never seen this happen myself, this make perfect sense. So why take a chance, these ABS unit cost a bunch.
So yes if you open the bleeders, bleed it and fush in some new fluid while your at it.
Mike
__________________
“The significant problems we have cannot be solved at the same level of thinking with which we created them” (Albert Einstein) Moderator Brake Forum
Re: if the bleeder valve is opened is bleeding required?
Just about every car manufacterer recommends opening the bleeder valves when compressing the calipers. In line with what the others were saying here, you will end up pushing sediment and debris into the abs unit. It's cheap insurance to bleed the system and flush some new brake fluid through.
This only takes a few minutes to do at most.
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2007 Tundra 5.7 4x2 RCSB slate metallic
2005 Corolla - all stock, cause it's the wifes
1986 Mustang GT - the stereo is under the hood
1990 Corolla - cause it was really cheap
Re: if the bleeder valve is opened is bleeding required?
I've always opened the bleed valve to compress the pistons, then topped of the brake fluid. (to make up for fluid pushed out) If you do brake front an rear at the same time, topping of isn't such a bad idea.
If you keep contant pressure on the piston before you open the bleed valve, and then close the valve just before fluid competely stops flowing, no air will get in and you won't have to bleed the lines. The same is true if you are going to change fluid and bleed them anyway. You still want to keep as much air out as possible.
Re: if the bleeder valve is opened is bleeding required?
Quote:
Originally Posted by MEvang
Sean is exactley right except for one lttle thing. If you have ABS it is better to open the bleeders when pushing the pistons back in. The reason why they say this is, small bits of sediment can end up in the calipers and if you push this stuff through the ABS unit these small pieces can get stuck in the small ports in the ABS or in the dump valve seats This can cause the ABS to fail.
Though I have never seen this happen myself, this make perfect sense. So why take a chance, these ABS unit cost a bunch.
So yes if you open the bleeders, bleed it and fush in some new fluid while your at it.
Mike
Re: if the bleeder valve is opened is bleeding required?
I first heard this in some ABS training seminars. This also has been mentioned in trade publications like Brake and Front End for example. These instructors and writer get this from first hand accounts or from manufacture training. So even though I haven't seen it happen I don't doubt it has.
I have seen plenty of small bits of debris build up in calipers. I can also tell you that many manufacture put screens in some of the ABS unit ports. And I have seen small bits stuck in these screens so this to me is another clue that this can happen.
Early Ford Ranger in particular had a lot of dump valve failure on their rear ABS models. I have taken a few apart and found them full of sediment. Usually this would affect the internal switch the let the ECU know the dump valve had seated. I don't know if this realy counts, but goes to show how crap in the brake fluid can have an affect on ABS parts.
Mike
__________________
“The significant problems we have cannot be solved at the same level of thinking with which we created them” (Albert Einstein) Moderator Brake Forum
if the bleeder valve is opened is bleeding required?
Re: if the bleeder valve is opened is bleeding required?
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