Master cylinder completely shot as of this morning... urgh.

[Bonneville92V688]

Yup, it's finally gone without little warning. The only problem before with the brakes was the pedal would very slowly sink to the floor, and I would have to lift up and put my foot on it again. But yeah, I hit the brakes today pulling in the driveway, pedal went to the floor, and the brake light came on, had to hit the emergency brake or I would have hit our Corvair at the end of the driveway, I even slid sideways. So now... I have to go to Napa to get a master cylinder, as AutoZone doesn't have one, nor does Advance, OR Federated. But the NAPA 5 miles away has one. So I am waiting for my Mom to show up to take me. Good thing I have today and tomorrow off from work.

So, I guess my question is how to bench bleed it. The guy at NAPA said the master cylinder will come with a kit to bench bleed it. Surprisingly, this is my first master cylinder replacment, so I am a virgin at it. Obviously I will have to bleed the whole system after installing the new master cylinder.

[bill buttermore]

Yup, it's finally gone without little warning. The only problem before with the brakes was the pedal would very slowly sink to the floor, and I would have to lift up and put my foot on it again.

Well, that was your warning - classic symptom of a leaking seal in the piston of the master cylinder.

Just follow the instructions for bench bleeding that will come with the master cylinder and you will be OK. Be careful not to let the MC reservoir drip empty on either end when you go to connect the brake lines to the cylinder, or the MC will need to be bench bled again. You will need to bleed the brake lines as well. Going to get the procedure for you....here ya' go: http://www.pontiacbonnevilleclub.com/fo ... ?f=19&t=99

Measure the length of your master cylinder to make sure the replacement is the same. Seems I recall they come in two different lengths.

[phils97bonn]

Got a cheap rebuild from Checker Auto. $78. Works great.

[John Deere Boy]

I had the long MS, replaced it with the short MS, no problems that i recall.

Don't let brake fluid get on your paint...it will peel it right off.

[Blazz]

I just did my MC, i was driving down the the road and, they went to the floor had to use the e-brake. I didn't bench bleed it like they said i put it on then bleed it,its easyer that way. I didn't have to bleed the whole system either they work 100% better hope i helped

[wjcollier07]

That's horrible advice not to bench bleed before installing. We're talking about brakes here...

Bench bleeding is super easy. Just follow the instructions in the box and the ones given and it'll all be good.

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