brake ? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

gary67 · 07-16-2008, 09:37 PM

i have been working on this 71 truck for a while and just started driving it
it seems like i have no power brakes
i took the mc off the booster and there was a small amount of fulid is this normal i am going to replace the booster also there is a wire hanging off the p valve what should that go to is ther any way to check and see if the valve is working
thanks for any and all help

70rs/ss · 07-16-2008, 09:52 PM

Change the whole thing, because if fluid did leak out of master (sounds like it did) it can be murder on the diapham inside the booster. Do you have good vacuum to the booster now? If it is hard I'd guess no vacuum to booster, if you have vacuum to the booster and the peddle is still hard the diaphram is leaking. The wire to the Prop Valve is a brake fluid indicator, brown wire and should go into the firewall plug. Good Luck!

**El Jay** · 07-16-2008, 09:54 PM

Fluid is not normal.
It means your MC is leaking.
You most likely have brake fluid in your vacuum booster now.

I'd replace the MC and the vacuum booster.

The wire is for your "Brake Warning light."

70rs/ss · 07-16-2008, 09:58 PM

Just to add to this, a master/booster combo is cheaper than buying seperately, i got my 3/4 ton 4X4 combo for like $120 at autozone.

07-16-2008, 09:37 PM	#1
gary67 Registered User Join Date: Nov 2005 Location: cedar hill tx Posts: 30	brake ? i have been working on this 71 truck for a while and just started driving it it seems like i have no power brakes i took the mc off the booster and there was a small amount of fulid is this normal i am going to replace the booster also there is a wire hanging off the p valve what should that go to is ther any way to check and see if the valve is working thanks for any and all help

07-16-2008, 09:52 PM	#2
70rs/ss Registered User Join Date: Dec 2004 Location: Northern AZ Posts: 7,271	Re: brake ? Change the whole thing, because if fluid did leak out of master (sounds like it did) it can be murder on the diapham inside the booster. Do you have good vacuum to the booster now? If it is hard I'd guess no vacuum to booster, if you have vacuum to the booster and the peddle is still hard the diaphram is leaking. The wire to the Prop Valve is a brake fluid indicator, brown wire and should go into the firewall plug. Good Luck!

07-16-2008, 09:54 PM	#3
El Jay Gone to greener pastures Join Date: May 2007 Location: Gateway to the Delta Posts: 7,354	Re: brake ? Fluid is not normal. It means your MC is leaking. You most likely have brake fluid in your vacuum booster now. I'd replace the MC and the vacuum booster. The wire is for your "Brake Warning light." __________________ '69 Chevy 1/2 T LWB Stepper: Daily Beater '72 GMC 3/4 T Fleet: Another Daily Beater '72 Plymouth Gran Coupe: ? "Ah women. They make the highs higher and the lows more frequent." Friedrich Nietzsche "Never kick a fresh turd on a hot day." Harry S. Truman GUN CONTROL: Never having to say, "I missed you." Always fire two warning shots into your attacker's chest area before putting a bullet between his eyes. Paraphrased from Louis Awerbuck

07-16-2008, 09:58 PM	#4
70rs/ss Registered User Join Date: Dec 2004 Location: Northern AZ Posts: 7,271	Re: brake ? Just to add to this, a master/booster combo is cheaper than buying seperately, i got my 3/4 ton 4X4 combo for like $120 at autozone.



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