abs/tc 5.3

[norm roy]

Hello : My question today is : When doing the brake fluid flush ( 60 k service, no changing of parts ) on a 1997 986 with abs/tc 5.3, Is it necessary to use the PST 2 ( to open the return pump and hydraulic solenoid valves ) as described in the bentley service manual, or is this procedure only used when changing out a brake component ? The instructions only talk about working the right rear valve ( bleeder ? ). I ordered the durametric this week for another issue, but it doesnt look like it will support the brake bleed process. Is it possible to supply 12 volts to these two solenoid valves through a terminal plug to open them up ?

Any input would be apriciated. Thanks : Norm

[ericinboca]

Hello : My question today is : When doing the brake fluid flush ( 60 k service, no changing of parts ) on a 1997 986 with abs/tc 5.3, Is it necessary to use the PST 2 ( to open the return pump and hydraulic solenoid valves ) as described in the bentley service manual, or is this procedure only used when changing out a brake component ? The instructions only talk about working the right rear valve ( bleeder ? ). I ordered the durametric this week for another issue, but it doesnt look like it will support the brake bleed process. Is it possible to supply 12 volts to these two solenoid valves through a terminal plug to open them up ?

Any input would be apriciated. Thanks : Norm

The ABS lines hold very little fluid. MO - you do not need the PST2 unless you have air in the ABS lines, and that is likely only if you are changing ABS components. I've completly removed the calipers on my 986, let the lines drip with fluid while I rebuilt, and then proceeded with a flush and several rounds of bleeding - no ABS activation and no problems at all. And during the bleeding, work your way around (assuming LHD) right rear, left rear, right front, left front.

[Loren]

If you are using compatible DOT 4 brake fluid then there is no need to bleed the ABS pump - there is very little in there to begin with.

If you are changing out a ABS valve or pump or switching to a synthetic brake fluid I think it would be a good idea.

[pk2]

Not to hijack but...

Is it time. or use, that breaks down brake fluid? Mine is a 99 but with just 34k on it...arid climate.

Regards, PK

Edited June 20, 2009 by pk2

[ericinboca]

Not to hijack but...

Is it time. or use, that breaks down brake fluid? Mine is a 99 but with just 34k on it...arid climate.

Regards, PK

I think it is time, water and contaminants - all related, with time being king, IMO.

Water in the fluid can boil and become vapor, which compresses and steals the pressure you want applied to the pads. Glycol based fluids absorb water, so the longer it is in the system, the more time it has to absorb water. With water, it begins to lose its anti corrosive nature, allowing more contamination.

I think Porsche's recommended interval is 2 years.