Silverado brake question

« **on:** March 17, 2014, 04:25:33 PM »

Not boat related but I'm baffled on what's going on. 3 months ago light went on and said service brake system. Noticed fluid was low so I topped it off and the the light went off. Now 2-3 months later the light comes back on and the fluid low again. At the MIN fill line. Looked over the truck can't find a leak no drips on the driveway. Not sure where else to look. Brakes seem to work as they did before.

« **Reply #1 on:** March 17, 2014, 04:43:53 PM »

Are your pads and shoes worn excessively? Rear shoes out of adjustment? The light will come on if there is excessive fluid movement in the system, kicking the piston in the proportioning valve to one side.

Had that happen on all three of mine, two 83 2WDs and an 87 4WD, when the inside pad disintegrated on the right front caliper. I think the slider mechanism in the caliper bound up.

Anyway, the fluid is going somewhere. If it isn't leaking, it is most likely displacing an overtraveled piston

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« **Reply #2 on:** March 17, 2014, 06:18:00 PM »

most tire shops do a brake inspection at no charge. Take it in and see what they say.

« **Reply #3 on:** March 17, 2014, 06:50:59 PM »

Take the master cylinder off and check for a leak going into the power brake unit , but leave the lines connected so you don't have to bleed it

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« **Reply #4 on:** March 18, 2014, 07:01:14 AM »

Quote from: rush1 on March 17, 2014, 06:50:59 PM

Take the master cylinder off and check for a leak going into the power brake unit , but leave the lines connected so you don't have to bleed it

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DING, DING, DING... my money is on this one!

« **Reply #5 on:** March 18, 2014, 02:20:52 PM »

Quote from: crewchief22 on March 18, 2014, 07:01:14 AM

DING, DING, DING... my money is on this one!

Have you seen that happen before? Where would it all be going?

« **Reply #6 on:** March 18, 2014, 02:25:19 PM »

Quote from: Flusher on March 17, 2014, 04:43:53 PM

Are your pads and shoes worn excessively? Rear shoes out of adjustment? The light will come on if there is excessive fluid movement in the system, kicking the piston in the proportioning valve to one side.

Had that happen on all three of mine, two 83 2WDs and an 87 4WD, when the inside pad disintegrated on the right front caliper. I think the slider mechanism in the caliper bound up.

Anyway, the fluid is going somewhere. If it isn't leaking, it is most likely displacing an overtraveled piston

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Remember its taken two bottles of for 3. That seems like a lot to just take up the displacement of a stuck piston

« **Reply #7 on:** March 18, 2014, 02:37:44 PM »

Quote from: Flusher on March 17, 2014, 04:43:53 PM

Are your pads and shoes worn excessively? Rear shoes out of adjustment? The light will come on if there is excessive fluid movement in the system, kicking the piston in the proportioning valve to one side.

Had that happen on all three of mine, two 83 2WDs and an 87 4WD, when the inside pad disintegrated on the right front caliper. I think the slider mechanism in the caliper bound up.

Anyway, the fluid is going somewhere. If it isn't leaking, it is most likely displacing an overtraveled piston

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Remember its taken two bottles of for 3. That seems like a lot to just take up the displacement of a stuck piston

« **Reply #8 on:** March 18, 2014, 03:32:40 PM »

Quote from: rush1 on March 17, 2014, 06:50:59 PM

Take the master cylinder off and check for a leak going into the power brake unit , but leave the lines connected so you don't have to bleed it

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Just did that. Sucked a water bottle full of fluid out of it with a little hand siphon pump. On the hunt for a new master cylinder =[ is bleeding the brakes still the same with the proportion valve thing?

« **Reply #9 on:** March 18, 2014, 03:35:48 PM »

Change the power brake unit .just buy a rebuilt power brake unit and a new master cylinder. That brake fluid will ruin the vacuum booster

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« **Reply #10 on:** March 18, 2014, 03:56:18 PM »

Quote from: rush1 on March 18, 2014, 03:35:48 PM

Change the power brake unit .just buy a rebuilt power brake unit and a new master cylinder. That brake fluid will ruin the vacuum booster

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What does it ruin? Isn't it just a metal drum basically? I'm not good just sucking it out and doing a new mast cylinder?

« **Reply #11 on:** March 18, 2014, 03:59:13 PM »

First off if your master cylinder is leaking it's junk and you could loose your brakes, second there's a rubber diaphragm inside that gets screwed up over time by brake fluid. So do your self the favor and replace both.

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« **Reply #12 on:** March 18, 2014, 06:50:39 PM »

Quote from: rush1 on March 18, 2014, 03:59:13 PM

First off if your master cylinder is leaking it's junk and you could loose your brakes, second there's a rubber diaphragm inside that gets screwed up over time by brake fluid. So do your self the favor and replace both.

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Copy that. Just ordered one of each couldn't find a parts store with either in stock. So this whole time my motor was breathing brake fluid?

« **Reply #13 on:** March 18, 2014, 07:20:41 PM »

Next time you go to get auto parts find a wholesale distributor in your area they'll probably have that in Stock and sell to the public at a better price , yeah it was burning a little brake fluid but it won't hurt anything, the best part is you didn't rear end anybody trying to stop in a panic., when you go to install that master cylinder you have to bench bleed it first .

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« **Reply #14 on:** March 18, 2014, 07:42:10 PM »

Check under the dash too...sometimes that brake fluid will follow the booster rod and you may find the carpet a little damp. Not very common at all, that rob runs through a watertight firewall grommet. But if your curious, its worth a peek..once the pbb and mc are replaced, then all you'd be doin under there is cleaning..

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« **Reply #15 on:** March 18, 2014, 08:13:11 PM »

Quote from: riverrat4life on March 18, 2014, 07:42:10 PM

Check under the dash too...sometimes that brake fluid will follow the booster rod and you may find the carpet a little damp. Not very common at all, that rob runs through a watertight firewall grommet. But if your curious, its worth a peek..once the pbb and mc are replaced, then all you'd be doin under there is cleaning..

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Haha I already checked for that when I was scopin out how to pull the booster. Nothin made it inside thank God

« **Reply #16 on:** March 18, 2014, 08:15:01 PM »

Quote from: rush1 on March 18, 2014, 07:20:41 PM

Next time you go to get auto parts find a wholesale distributor in your area they'll probably have that in Stock and sell to the public at a better price , yeah it was burning a little brake fluid but it won't hurt anything, the best part is you didn't rear end anybody trying to stop in a panic., when you go to install that master cylinder you have to bench bleed it first .

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I usually get my stuff from cal state auto but they decided they didn't wanna sell to the Public at all today when I called. it's hit or miss with them.

Bench bleed? I've never heard of that?

« **Reply #17 on:** March 18, 2014, 08:22:10 PM »

If you don't the master cylinder will have air stuck in it , usually the master will come with some plastic hoses, install them and have the end of the hose going into the fluid reservoir fill the master up with fluid and pump the master until you Don't see any air bubbles if it doesn't come with hoses then fill the master up with brake fluid ( mount the master in a vice) and push the piston on the master in all the way now don't let the piston return until you put your fingers in the hole

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« **Reply #18 on:** March 18, 2014, 08:24:17 PM »

That way it can't such air back into the master keep doing this until you get a clean shot of brake fluid with no bubbles in it , install the master and test the brakes your done enjoy your ride.

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« **Reply #19 on:** March 18, 2014, 08:45:18 PM »

Quote from: rush1 on March 18, 2014, 08:24:17 PM

That way it can't such air back into the master keep doing this until you get a clean shot of brake fluid with no bubbles in it , install the master and test the brakes your done enjoy your ride.

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Sounds good . Appreciate the help man!

« **Reply #20 on:** March 18, 2014, 08:47:00 PM »

No proproblem if you have any more questions just Holla at me

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