Power Brake Flush question
Discussion
Hi All,
Hope someone can help with this query please and I apologise in advance if this is a stupid question.
I have a Porsche 911 997.2 which was due for a big service, but I have done most of the things myself due to main dealer quoted prices. Drive belt, plugs, filters and rear, lower suspension arms have all been changed.
As part of the service though I need to do the 2 yearly brake flush and I have decided to use a power flusher for the first time .
My question is, can this power flusher tool introduce air into the system?
I dont mean if the fluid in the main container gets too low or anything like that, what I mean is, when you connect the main unit onto the master cylinder top, the feed pipe is full of air and what happens to this air when you pressurise the power bleeder and when you open the brake nipples and bleed the system? Surely, this volume of air has to go somewhere and that is straight into your braking system!
Similarly, unless your master cylinder tank is brim full when you connect the power bleeder, this must also have a small amount of air in it before you connect your power bleeder. What happens to this air?
Surely, as you start to bleed your brakes and the whole system is pressurised, there is nowhere for this residual air to go other than into your braking lines?
I have watched loads of You tube videos on how to bleed brakes using a power bleeder, but not one person mentions this as being a problem.
Massive apologies guys if I am being thick here but can anyone clarify here please? What happens to this residual air as I dont want to unecessarily introduce air into my braking system.
Cheers.
Barry.
Hope someone can help with this query please and I apologise in advance if this is a stupid question.
I have a Porsche 911 997.2 which was due for a big service, but I have done most of the things myself due to main dealer quoted prices. Drive belt, plugs, filters and rear, lower suspension arms have all been changed.
As part of the service though I need to do the 2 yearly brake flush and I have decided to use a power flusher for the first time .
My question is, can this power flusher tool introduce air into the system?
I dont mean if the fluid in the main container gets too low or anything like that, what I mean is, when you connect the main unit onto the master cylinder top, the feed pipe is full of air and what happens to this air when you pressurise the power bleeder and when you open the brake nipples and bleed the system? Surely, this volume of air has to go somewhere and that is straight into your braking system!
Similarly, unless your master cylinder tank is brim full when you connect the power bleeder, this must also have a small amount of air in it before you connect your power bleeder. What happens to this air?
Surely, as you start to bleed your brakes and the whole system is pressurised, there is nowhere for this residual air to go other than into your braking lines?
I have watched loads of You tube videos on how to bleed brakes using a power bleeder, but not one person mentions this as being a problem.
Massive apologies guys if I am being thick here but can anyone clarify here please? What happens to this residual air as I dont want to unecessarily introduce air into my braking system.
Cheers.
Barry.
Bajers said:
Surely, this volume of air has to go somewhere and that is straight into your braking system!
there is nowhere for this residual air to go other than into your braking lines?
Depending how the pressurised supply is connected, the air in the reservoir will either bubble up into the pressurised supply or stay where it is. You'd need a massive flow rate to drag air downwards into the system, and you never get anywhere near that when bleeding brakes.there is nowhere for this residual air to go other than into your braking lines?
Is is a pressure bleeder or vacuum bleeder?
If a pressure bleeder, the only way it will introduce air is if the container runs out of fluid. In many modern cars, you will need to run the ABS pump as part of the bleeder or else the system won't properly bleed. That requires a compatible scan tool
If a pressure bleeder, the only way it will introduce air is if the container runs out of fluid. In many modern cars, you will need to run the ABS pump as part of the bleeder or else the system won't properly bleed. That requires a compatible scan tool
All you need to consider is where in the reservoir the fluid outlets are (clue: at the bottom). Keep those outlets covered at all times whilst bleeding and you'll be OK. It's fine to uncover them whilst sucking out the old fluid, but make sure that you refill to level with new fluid before connecting your pressure vessel.
I have never had to 'run the ABS pump' on any car whilst bleeding... unless air has been introduced into the ABS unit.
I have never had to 'run the ABS pump' on any car whilst bleeding... unless air has been introduced into the ABS unit.
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