# Absolutly nessacary to bench bleed MC before install?



## vwguy3 (Jul 30, 2002)

I hope it is because I didn't have any port plugs to bench bleed it. I kind of tried with the plastic plugs. Don't think it helped. I haven't bleed the brake system yet, but am going to do it soon. will all of the air in the MC come out with out bench bleeding.
Thanks
Justind


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## DemonEater (Jan 29, 2001)

*Re: Absolutly nessacary to bench bleed MC before install? (vwguy3)*

It really really really really helps to bench-bleed it.
If the car is nice and level, and you're patient, you can often manage a decent bleed simply on the car, but you're much more likely to have problems. Don't say we didn't warn you, in other words.
Do you not have any way to go buy bench-bleeding supplies?


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## vwguy3 (Jul 30, 2002)

*Re: Absolutly nessacary to bench bleed MC before install? (DemonEater)*

No I don't have the stuff to do a bench bleed. I wasn't aware of the need to do it. It was my first time doing a MC change. Tried to bleed all of the lines hoping that I could work all of the air out. Is it possible to get all of the air out of the new MC just by bleeding the lines at the calipers, or should I get some plugs and do a bench bleed? What type of plug do I need if I decide to get the plugs.
Thanks
Justind


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## wjbski (Feb 1, 2003)

*Re: Absolutly nessacary to bench bleed MC before install? (vwguy3)*

If you can get a helper to pump the brake pedal for you, you can crack open each hard line where it threads into the M/C. This will get out most of the air. What I use is some hard lines that a junk yard car "donated" to me. I just re-bent them so they curl into the reservoir. Works great.


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## fat biker (Feb 16, 2001)

FWIW, first VW MC replacement I ever did, no bench bleed. No problem bleeding the brakes for that install.
fat biker


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## vwguy3 (Jul 30, 2002)

*Re: (fat biker)*

The problem that I am getting is that there is more petal and brakes than before. But they are still spongy, and I don't know if I didn't bleed them enough or if there is a brake booster problem. because when I got in the car and pushed the petal it felt pretty hard and then when I started the car it went soft and spongy. FYI this is for an 84 rocco.
Thanks
Justind


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## vwguy3 (Jul 30, 2002)

*Re: (vwguy3)*


_Quote, originally posted by *vwguy3* »_The problem that I am getting is that there is more petal and brakes than before. But they are still spongy, and I don't know if I didn't bleed them enough or if there is a brake booster problem. because when I got in the car and pushed the petal it felt pretty hard and then when I started the car it went soft and spongy. FYI this is for an 84 rocco.
Thanks
Justind


Bump
Justind


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## DemonEater (Jan 29, 2001)

*Re: (vwguy3)*

Likely still air somewhere in the system.
I had awful pedal feel after just doing pads, rotors, shoes, and drums on my car. Leaky wheel cylinder on passenger side - I bled it myself, which made things a little better, but not perfect.
After replacing the wheel cylinder today and using a pressure bleeder on just that one wheel, the brakes feel GREAT.


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## vwguy3 (Jul 30, 2002)

*Re: (DemonEater)*


_Quote, originally posted by *DemonEater* »_Likely still air somewhere in the system.
I had awful pedal feel after just doing pads, rotors, shoes, and drums on my car. Leaky wheel cylinder on passenger side - I bled it myself, which made things a little better, but not perfect.
After replacing the wheel cylinder today and using a pressure bleeder on just that one wheel, the brakes feel GREAT.

Thanks I think I'll try and bleed it some more. Brand new wheel cylinders on both rears and newer brake calipers with new pads and rotors.
Justind


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## bkschott (Jun 11, 2006)

*Re: Absolutly nessacary to bench bleed MC before install? (wjbski)*


_Quote, originally posted by *wjbski* »_If you can get a helper to pump the brake pedal for you, you can crack open each hard line where it threads into the M/C. This will get out most of the air. What I use is some hard lines that a junk yard car "donated" to me. I just re-bent them so they curl into the reservoir. Works great.

bump for this is exactly what the hell I was looking for, thanks.


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## jamesb (Mar 14, 2001)

*Re: Absolutly nessacary to bench bleed MC before install? (bkschott)*

Just as easy, if you know a local that has a motiv power bleeder you can also just use that to push the fluid through the MC and out to the calipers. Thats usually how I get a new MC going before I do any pump based bleeding.


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## speeding-g60 (Aug 1, 2004)

*Re: Absolutly nessacary to bench bleed MC before install? (jamesb)*


_Quote, originally posted by *jamesb* »_
Just as easy, if you know a local that has a motiv power bleeder you can also just use that to push the fluid through the MC and out to the calipers. Thats usually how I get a new MC going before I do any pump based bleeding.

the Motive... FTW. it works.... i WAS an unbeliever, not anymore. i got one. no more wife trying to pump the brakes, etc LOL
this is the exact one i got:
http://cgi.ebay.com/ebaymotors...ZWDVW


_Modified by speeding-g60 at 6:19 PM 5-11-2008_


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## jamesb (Mar 14, 2001)

*Re: Absolutly nessacary to bench bleed MC before install? (speeding-g60)*

It is nice and on a street car its all you need. On my race cars I use both a motive for replacements and getting around the bench bleeding. But for weekend bleeds at the track after qualifing I have speed bleeders. These are nice because a 1/4 turn is all you need and 2-3 pumps of the pedal and that caliper is completely bled out.


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## techfx (Oct 16, 2008)

*Re: Absolutly nessacary to bench bleed MC before install? (jamesb)*

I have a MC that I let the rear lines run dry when taking out the rear axle. I tried to hand vacuumpump the rear lines and just bled the fron normal. I don't have any more air comming out but, still a soft pedal Will I need to remove and bleed the master cylinder or can I get the air out by vacuum bleeding the front brakes like I did the rear? they're just harder to get to since the wheels are still on.


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## GTijoejoe (Oct 6, 2001)

*Re: Absolutly nessacary to bench bleed MC before install? (vwguy3)*

Pressure bleeding will be your best option.... 
Remember OEM vehice MC's are not bench bled.....but often they use a vacuum system.


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## techfx (Oct 16, 2008)

*Re: Absolutly nessacary to bench bleed MC before install? (GTijoejoe)*


_Quote, originally posted by *GTijoejoe* »_Pressure bleeding will be your best option.... 
Remember OEM vehice MC's are not bench bled.....but often they use a vacuum system.

Well, I ordered and tried the motive power bleeder and went through a half gallon of fluid bleeding in the correct order - still not a full pedal (it does build some pressure after multiple pumps now. I'm wondering if it's the MC or Proportioning valve.


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## germancarnut51 (Mar 23, 2008)

*Re: Absolutly nessacary to bench bleed MC before install? (techfx)*

Do you have the rear of the car on jackstands or on the ground? If on jackstands, do you have them located under the rear beam supporting the back of the car (and the wheels) in the same position that they sit in when the wheels are on the ground or are you supporting the car on the chassis lift points with the rear wheels drooping down?
If you're trying to bleed the rear brakes with the car lifted and the rear wheels drooping, the rear mounted proportioning valve is restricting the fluid flow to the rear brakes and they will not bleed (pass fluid) properly. When you bleed the rear brakes, place your jackstands under the rear beam, holding the wheels up, or crawl under the car while it's sitting on the wheels and bleed the brakes (this is the way I do it).
The front brakes need to bled as well, because VW (most atleast) have diagonal braking with each rear brake tied to the front brake on the opposite side. So if you open the rear brakes, you must bleed the fronts also. Same thing goes for servicing the front brake. Open a front brake, and you must bleed the rear brakes as well.


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## techfx (Oct 16, 2008)

*Re: Absolutly nessacary to bench bleed MC before install? (germancarnut51)*


_Quote, originally posted by *germancarnut51* »_Do you have the rear of the car on jackstands or on the ground? If on jackstands, do you have them located under the rear beam supporting the back of the car (and the wheels) in the same position that they sit in when the wheels are on the ground or are you supporting the car on the chassis lift points with the rear wheels drooping down?
If you're trying to bleed the rear brakes with the car lifted and the rear wheels drooping, the rear mounted proportioning valve is restricting the fluid flow to the rear brakes and they will not bleed (pass fluid) properly. When you bleed the rear brakes, place your jackstands under the rear beam, holding the wheels up, or crawl under the car while it's sitting on the wheels and bleed the brakes (this is the way I do it).
The front brakes need to bled as well, because VW (most atleast) have diagonal braking with each rear brake tied to the front brake on the opposite side. So if you open the rear brakes, you must bleed the fronts also. Same thing goes for servicing the front brake. Open a front brake, and you must bleed the rear brakes as well.


I had the car level (ramps front, rear jack stands) as I did when I replaced my scirocco 16v rear calipers w/ mk3 gti calipers last year. I have to have those off the car and upside down to bleed properly (due to brake line being at the bottom instead of top on the scirocco). I don't see any proportioning valve near the rear axle. I've probably had at least 3/4 gallon of fluid from bleeding all 4 wheels.


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## techfx (Oct 16, 2008)

*Re: Absolutly nessacary to bench bleed MC before install? (techfx)*


_Quote, originally posted by *techfx* »_

I had the car level (ramps front, rear jack stands) as I did when I replaced my scirocco 16v rear calipers w/ mk3 gti calipers last year. I have to have those off the car and upside down to bleed properly (due to brake line being at the bottom instead of top on the scirocco). I don't see any proportioning valve near the rear axle. I've probably had at least 3/4 gallon of fluid from bleeding all 4 wheels.

While bench bleeding the new MC (with proportioning valve installed as instructions recommended) I was able to get fluid out of 3 /4 ports but, nothing out of the proportioning valve. I was getting fluid from all 4 lines when bleeding with the previous MC. Any idea what I'm doing wrong?


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