Hi

Do a use new fluid to push the old fluid out or syringe the old fluid out of the reservoir pot first then pressure bleed the new fluid through to push the old fluid out in the correct sequence.

Thanks Graeme

If you have a syringe handy feel free to remove most of the old brake fluid from the reservoir pot and top up with new before pressure bleeding.

 

It doesn't make much difference as you can always push out the old fluid using a pressure bleeder before adding new.

 

The most important thing is not to let the reservoir run dry as once air is in the system it can be hard to remove from the ABS pump :)

Cheers

Just wasn't sure if a could use new fluid to push the old fluid out for contamination new to old.

A thought empty the hole system then put new fluid in.

I have always kept the reservoir topped up in the bleeder and just cracked each corner (usually starting furthest from master cylinder) allowing the fluid to flow until clean (plus about 30 seconds after to make sure)

If you have a syringe handy feel free to remove most of the old brake fluid from the reservoir pot and top up with new before pressure bleeding.

 

It doesn't make much difference as you can always push out the old fluid using a pressure bleeder before adding new.

 

The most important thing is not to let the reservoir run dry as once air is in the system it can be hard to remove from the ABS pump :)

Use a vacuum bleeder, not a pressure bleeder, to make certain you don't push air into the ABS valve block. If you do, you need a VCDS bleed to get it back out.

Use a vacuum bleeder, not a pressure bleeder, to make certain you don't push air into the ABS valve block. If you do, you need a VCDS bleed to get it back out.

 

The VAS 5234 is the tool a Skoda dealer would use and is a pressure bleeder if memory serves.

 

Not sure how a vacuum bleeder would reduce the risk of air entering the system? If the master cylinder runs out of fluid, you'll still get air in the system...

The VAS 5234 is the tool a Skoda dealer would use and is a pressure bleeder if memory serves.

 

Not sure how a vacuum bleeder would reduce the risk of air entering the system? If the master cylinder runs out of fluid, you'll still get air in the system...

If delta P between environment and bleeder exceeds 15PSI then you get a higher risk of pushing air bubbles into the system.

If delta P between environment and bleeder exceeds 15PSI then you get a higher risk of pushing air bubbles into the system.

 

VAG recommend setting the pressure at 2 bar (~29 psi) on the MK2 Octavia, suggesting if the risk is increased, it creates few issues in the real world: http://workshop-manuals.com/skoda/octavia-mk2/brake_systems/brakes_hydraulics_regulator_servo/bleeding_brake_system/bleeding_the_brake_system_of_air_with_the_brake_filling_and_bleeding_device/

 

The most likely cause for air ingress will be not keeping the reservoir filled up or using aerated fluid, either will cause issues for both vacuum and pressure bleeding methods.

 

People have preferred methods, I'm sure the OP will choose one based on their experience and equipment regardless of pros/cons :)

Thanks very much for that

Graeme

Do a use

 

F*ck me, never seen anyone WRITE in Geordie?!! :o :rofl:

Well ya Na that's geordie for ya