DIY: Brake Flush - 986 Forum - The Community for Porsche Boxster & Cayman Owners

986Porsche986 · 11-15-2008, 01:20 PM

According to this tutorial, you are to use the empty Motive to push ALL of the old fluid out of the system and into a waste bottle at the rear right bleed valve until you hear the sound of gurgling air coming out of the valve. Wont this method allow air into the system? I have read other posts where this method is also used, but just enough to only lower the fluid in the reservoir to just above the sensor, then start bleeding with a filled Motive pressure bleeder. Can any "experts" chime in and let me know if the method in the attached PDF is incorrect? Thanks.

Adam · 11-15-2008, 01:28 PM

Quote:

Originally Posted by 986Porsche986

According to this tutorial, you are to use the empty Motive to push ALL of the old fluid out of the system and into a waste bottle at the rear right bleed valve until you hear the sound of gurgling air coming out of the valve. Wont this method allow air into the system? I have read other posts where this method is also used, but just enough to only lower the fluid in the reservoir to just above the sensor, then start bleeding with a filled Motive pressure bleeder. Can any "experts" chime in and let me know if the method in the attached PDF is incorrect? Thanks.

Yeah, you don't want the resevoir to go empty or there is a very good possibility air will get in the system.

jmatta · 11-15-2008, 01:35 PM

Woah!!! Stand back, young man. Do not bleed to the point where you introduce air into the system. It takes forever to get it out, especially in a modern car. I've been tracking 911s for years and do my own brake work. The Motive is a great product, but always keep an eye on the reservior. I would be hard pressed to drive any car that got that much air in the system.

I'm sure Tool Pants can chime in to let us know what that much air does to the master cylinder, let alone the ABS system.

JFP in PA · 11-15-2008, 07:13 PM

Quote:

Originally Posted by jmatta

Woah!!! Stand back, young man. Do not bleed to the point where you introduce air into the system. It takes forever to get it out, especially in a modern car. I've been tracking 911s for years and do my own brake work. The Motive is a great product, but always keep an eye on the reservior. I would be hard pressed to drive any car that got that much air in the system.

I'm sure Tool Pants can chime in to let us know what that much air does to the master cylinder, let alone the ABS system.

Getting air into the ABS system requires the use of a PST II/PIWIS diagnostic unit to get it out..................bad idea.

wconley · 11-17-2008, 08:38 AM

One comment/question regarding the pressure bleeder. The write-up suggests 20psi but I've heard that 14-15psi is as high as you want to go to protect the seals. Is it that 14-15psi is overly conservative? I've bled my M3 many times with 14psi with no problems but haven't needed to flush the Boxster yet. Thanks, and good write-up.