Hydroboost brake issues, Need some info please?? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Mangled03gmc · 12-06-2012, 01:06 PM

Ok so the other day I noticed the brakes on the truck getting a little soft, then the next more, now this morning they would go all the way to the floor, no brakes at all, reguardless if the truck is running or not. I am not versed huge in the whole hydro boost thing, but do know not to jump to the conclusion of a bad master cylinder, even though that is prob the issue. Turing the wheel lock to lock and holding it, i hear no hissing sound at all. Could the spool valve or accumulator be bad? If so what is the best way to check this? No leaks anywhere in the system, as I do not see fluid disappearing. Thanks for any help or info guys..

Mangled03gmc · 12-06-2012, 09:25 PM

Some one any one care to shine some light on teh subject. Help a brova out. Thanks

J Knight · 12-06-2012, 09:51 PM

Im no expert on hydroboost either but it sound mastercylinderish to me.

**hatzie** · 12-07-2012, 10:36 AM

That sounds more like a master cylinder. A bad booster should make the pedal stiff... braking will feel like the engine is off.

Mangled03gmc · 12-07-2012, 02:16 PM

Hmm interesting. I guess I will get a new MC, see whats up..

Mangled03gmc · 12-07-2012, 03:05 PM

Well went ahead and snagged a new MC. Well see if this was it.

bohmankid · 12-07-2012, 03:18 PM

My pedal went all the way to the floor. It was my master cylinder. took 20 minutes to replace, just follow instructions.
My friends pedal is stiff as hell. His was the the brake booster.

12-06-2012, 01:06 PM	#1
Mangled03gmc Registered User Join Date: Nov 2012 Location: MD Posts: 21	Hydroboost brake issues, Need some info please?? Ok so the other day I noticed the brakes on the truck getting a little soft, then the next more, now this morning they would go all the way to the floor, no brakes at all, reguardless if the truck is running or not. I am not versed huge in the whole hydro boost thing, but do know not to jump to the conclusion of a bad master cylinder, even though that is prob the issue. Turing the wheel lock to lock and holding it, i hear no hissing sound at all. Could the spool valve or accumulator be bad? If so what is the best way to check this? No leaks anywhere in the system, as I do not see fluid disappearing. Thanks for any help or info guys.. __________________ JOHN Dads 83 RCLB dually, BBC, 400 turbo, Under construction Mine 03 Sierra RCSB,6.0, boost, a bunch of other goodies Last edited by Mangled03gmc; 12-06-2012 at 01:21 PM.

12-06-2012, 09:25 PM	#2
Mangled03gmc Registered User Join Date: Nov 2012 Location: MD Posts: 21	Re: Hydroboost brake issues, Need some info please?? Some one any one care to shine some light on teh subject. Help a brova out. Thanks __________________ JOHN Dads 83 RCLB dually, BBC, 400 turbo, Under construction Mine 03 Sierra RCSB,6.0, boost, a bunch of other goodies

12-06-2012, 09:51 PM	#3
J Knight Registered User Join Date: Jun 2011 Location: Baytown TX Posts: 2,219	Re: Hydroboost brake issues, Need some info please?? Im no expert on hydroboost either but it sound mastercylinderish to me. __________________ John 82 Chevy Silverado 350ci/TH350

12-07-2012, 10:36 AM	#4
hatzie Moderator Join Date: Oct 2008 Location: Wentworth, NH Posts: 4,977	Re: Hydroboost brake issues, Need some info please?? That sounds more like a master cylinder. A bad booster should make the pedal stiff... braking will feel like the engine is off. __________________ 1959 M35A2 LDT465-1D SOLD 1967 Dodge W200 B383, NP420/NP201 SOLD 1969 Dodge Polara 500 B383, A833 SOLD 1972 Ford F250 FE390, NP435/NP205 SOLD 1976 Chevy K20, 6.5L, NV4500/NP208 SOLD 1986 M1008 CUCV SOLD 2000 GMC C2500, TD6.5L, NV4500 2005 Chevy Silverado LS 2500HD 6.0L 4L80E/NP263 2009 Impala SS LS4 V8 RTFM... GM Parts Books, GM Schematics, GM service manuals, and GM training materials... 1973-1991 GM Light Truck Service, Unit/Overhaul, Wiring Manuals, Parts Books and Some 1968-1999 GM Service Training textbooks in PDF 1988-1998 GMT400 CK service manual project 1988-1993 GMT400 CK parts books. 1967-1972 GM Light, Medium, & Heavy Truck Service Manuals in PDF Please include at least the year and model in your threads. It'll be easier to answer your questions. And please let us know if and how your repairs were successful.

12-07-2012, 02:16 PM	#5
Mangled03gmc Registered User Join Date: Nov 2012 Location: MD Posts: 21	Re: Hydroboost brake issues, Need some info please?? Hmm interesting. I guess I will get a new MC, see whats up.. __________________ JOHN Dads 83 RCLB dually, BBC, 400 turbo, Under construction Mine 03 Sierra RCSB,6.0, boost, a bunch of other goodies

12-07-2012, 03:05 PM	#6
Mangled03gmc Registered User Join Date: Nov 2012 Location: MD Posts: 21	Re: Hydroboost brake issues, Need some info please?? Well went ahead and snagged a new MC. Well see if this was it. __________________ JOHN Dads 83 RCLB dually, BBC, 400 turbo, Under construction Mine 03 Sierra RCSB,6.0, boost, a bunch of other goodies

12-07-2012, 03:18 PM	#7
bohmankid Registered User Join Date: Nov 2012 Location: Salt Lake City, UT Posts: 520	Re: Hydroboost brake issues, Need some info please?? My pedal went all the way to the floor. It was my master cylinder. took 20 minutes to replace, just follow instructions. My friends pedal is stiff as hell. His was the the brake booster. __________________ My 1985 GMC 4x4 LS swap build thread R.I.P. My 1978 Big Ten, Big Block build thread Moby: My Chevy 4x4 ls swap build thread

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