Yaba Daba Dooo

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Apr 16, 2017 | 12:03 AM

timmyboy76

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Yaba Daba Dooo

Had to get the audience's attention.... With a new hydroboost, master cylinder and as of tonight, a nee power steering pump along with freshly greased slidepins,.. What v would cause the brake pedal to slowly lose pressure and fall to the floor, while waiting at a stoplight? The truck stops great, pedal feels supurb and no leaking..so, what gives...

Apr 16, 2017 | 12:05 AM

andym

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From: Bonita Springs FL

A bad master cylinder is really the only thing that can cause that behavior.

Where did you buy your parts from?

Apr 16, 2017 | 12:28 AM

timmyboy76

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Napa, Andy... It's the exact same symptom presented and the v reason fit chasing it. Not much left to replace.

Apr 16, 2017 | 09:10 AM

andym

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Napa doesn't sell the highest quality stuff. It's not uncommon to get a bad master out of the box. You get what you pay for.

Apr 16, 2017 | 09:35 AM

timmyboy76

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I hear ya, but the same result from an OEM to a new out of box unit...

Apr 16, 2017 | 09:49 AM

andym

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From: Bonita Springs FL

There's also another possibility... a fluid leak in the system.

So how many master cylinders have you put on this?

Apr 16, 2017 | 10:24 PM

FiznUKa

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From: Salt Lake City, utah

Do you lose fluid? Could possibly be the line in the frame behind the fuel tank.

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Apr 17, 2017 | 06:02 AM

Rikster-7700

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From: Jacksonville, FL

Have bled all of the air out of the system?

Apr 17, 2017 | 08:37 AM

#10

timmyboy76

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Yeah, bled her twice. Maybe I'll throw at him to get some speed bleeders for reassurance

Apr 17, 2017 | 08:41 AM

#11

andym

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From: Bonita Springs FL

Air in the system doesn't cause the behavior you describe.

Apr 17, 2017 | 08:52 AM

#12

timmyboy76

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You just saved us time and money Andy...right on!
Could written out soft brake lines be a culprit? Thrusting days now since the entire system minutes the abs, had been gone thew

Apr 17, 2017 | 09:01 AM

#13

andym

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From: Bonita Springs FL

In general, it's not a bad idea to replace the soft lines on an older truck. But you never said how old your truck is.

I replaced mine with stainless steel braided lines meant for a small lift. They work great and noticeably improved stopping power over my 17-year old soft lines.

However, the lines can't cause a sinking pedal. Again as I said earlier - you either have a fluid leak or a bad master cylinder and it's NOT unheard of at all to get a bad one out of the box. This is why most people have learned not to buy brake parts at Napa.