911 SC Motive Pressure Bleeder Trouble

[2jmotorsports]

Guys,

Having some trouble bleeding my brakes with my Motive bleeder. I bought it over a year ago and have used it on other vehicles before with no issues which is why I am scratching my head trying to bleed my 83 SC brakes. My brakes work fine, I am only flushing with new fluid because I dont know how old the existing fluid is.

So I fill the Motive bottle with some fluid and hookup the hose to top of the MC reservoir.




As I start pumping and building pressure I hear a stream of fluid hitting the floor. I panicked for a second and thought I had a torn line but I realized fluid was pouring out of a drain in the driver side front wheel well. I followed the small braided line coming out of the side of the MC reservoir and it does indeed connect to that same drain line.





So I dumped most of my fresh fluid on the ground through that drain. If this is an overfill drain for the reservoir not sure how to get around it to build pressure and flush the existing fluid without making a mess. Pointers? Plug the drain and try to bleed again?

[Green6]

That braided line is the vent for the M/C reservoir . You need to pull the line off the side of the M/C reservoir and cap off the reservoir. I used a short piece of line with a golf tee jammed in it. That will allow you to build pressure with the Motive bleeder in the M/C reservoir to bleed your brakes. Remember to replace the vent line when you are finished bleeding.

Most other M/C reservoirs have the vent built into the cap, so that is why there was no extra line to cap off.

[pjd131]

Or, you can crimp the line as shown in this pic.

[puddy]

Yup, I just realized the same thing last weekend when using my motive bleeder for the first time. Couldn't get pressure to build in the tank then I realized I had to block the overflow tube. Then worked perfectly.

[jlex]

Be careful of those Motive bleeders when you use fluid in them (they can be used w/o fluid if you keep a good eye on the reservoir level). The lines deteriorate after a few years & will break, throwing brake fluid all over your trunk
I've actually moved up to a vacuum-type bleeder that I hook up to the compressor to do the job. It uses an auto-fill bottle (holds a quart) mounted on top the reservoir which automatically feeds fluid during the process.
This: Super price on MityVac MV6835 at ToolTopia.com

[john walker's workshop]

I use air pressure only in mine. Drilled a hole in the top and installed a steel tire valve because the hand pump is too slow. Works great. Just keep the reservoir topped up. Needle nose vise grips to clamp the overflow hose.

[2jmotorsports]

Thanks for the feedback. I think I know where to take it from here!

[Spenny_b]

Just bled my brakes (and clutch) on my 965 using a very similar setup to the Motive (actually a Sealey V820, really well made piece of kit for £40/$60)....don't use more than 20-22psi; the 964 Porsche Workshop Manuals state 21.75psi (!), the instructions for the pressure bleeder state 20psi...I went with 22 and it worked a charm, brakes done in less than 15mins, same exercise as you, purging old fluid.

I like Johns idea of installing a Schrader valve into the bottle - it does need quite some pumping to get the pressure back every time a refill is needed.

[famoroso]

I employ the suck and blow method by using both a Motive pressure bleeder at the reservoir as well as a Mityvac vacuum bleeder at the calipers / clutch slave cylinder. More is better, right?

[Bob Kontak]

Use any method. Gravity, suction, Motive air, Motive fluid, one way bleeders, friend pedal pushing method.

Just do it again a few days later after shaking it up from driving.

You know you got it when you cannot feel that "step" anymore in the pedal. I am talking one point five inches of travel, then a brick wall. Bone stock.

I have done it with stock SC calipers and my why the hell did I buy these Boxster upgrade calipers. Damn, they look good though, with the cross drilled rotors, on the way to the grocery store.

FWIW: They do pull the car down from speed differently. Glad I spent the dough. Kind of an overkill for a "wimp" driver, though.

[Menmojo]

Use a needle nose vise grip on the overflow tube to keep pressure in the system. That's the source of your leak. Be very careful not to put to much pressure in the system or you risk blowing off/damaging the hoses going from the reservoir into the braking system.
I only use 6-8psi. 20 psi is asking for trouble IMHO.

[Ronnie's.930]

Originally Posted by Bob Kontak

Just do it again a few days later after shaking it up from driving.

Only if one is a chimp that couldn't do the job correctly the first time, bro!

[Bob Kontak]

Originally Posted by Menmojo

Use a needle nose vise grip on the overflow tube to keep pressure in the system. That's the source of you leak. Be very careful not to put to much pressure in the system or you risk blowing off/damaging the hoses going from the reservoir into the braking system.
I only use 6-8psi. 20 psi is asking for trouble IMHO.

Agree. I am in the 13-15 psi club.

However, once the pedal is pushed would love to know the dynamics of the mid year Porsche braking system. 6-8 or 15 psi is child's play. Have read with the 356, the brake manufacturer said NO to Porsche with respect to brake warranty/liability. Aggressive valving, etc.

There are reasons for late apex braking efficiency. Build quality coupled with risk.

Reading vs. experiencing. I am a giant pussy.

That said, 8 psi can bleed the system just fine. Do it a couple times though.

[Bob Kontak]

Originally Posted by Ronnie's.930

Only if one is a chimp that couldn't do the job correctly the first time, bro!

Did someone just hear a flatulating douche nozzle noise? I swear to God I did. Must be just me.

[Ronnie's.930]

Originally Posted by Bob Kontak

Did someone just hear a flatulating douche nozzle noise? I swear to God I did. Must be just me.

You heard a noise all right, butt it was "zing, boom, spank"!

[Bob Kontak]

Originally Posted by Ronnie's.930

Only if one is a chimp...........

There is only one Chimp. In caps, dawg. Pieholio in the Pre-Cambrian era (1960's).

Lancelot Link. Don't dis my ex-Ho' either. Mata Hari. Tang el-supremo. Tight. I miss her since Eric stole her from me.

Stand down, right now.



Oh yeah. On topic. Bleed again after a couple of days.

[Ronnie's.930]

^^^

Nice picture of you and yer 5th ex-wife, butt I'm just thankful that your sister didn't get the infamous, Kontak body hair gene!!!!

[Bob Kontak]

Originally Posted by Ronnie's.930

Nice picture of you and yer 5th ex-wife, butt I'm just thankful that your sister didn't get the infamous, Kontak body hair gene!!!!

Seventh. But............As long as Eric's happy. That's all that counts.

[Ronnie's.930]

Originally Posted by Bob Kontak

Oh yeah. On topic. Bleed again after a couple of days.

A step applicable to Targas only; apparently the extreme chassis flex inherent to the U-shaped tub allows previously purged air to re-enter the hydraulic system!

[Bob Kontak]

Leave my sister out of this. The membership is furious about your incessant palavering with respect to a world renowned throw-down. Give her some respect.