Squishy brakes. Help!? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

KaptinK5 · 03-02-2011, 03:40 AM

Today I was helping a friend work on his truck. After I left the brakes on my 86 blazer began to seem slightly soft but were still working fine. I later got in my blazer and found that my brakes have no power at all now and go right to the floor. I have no visible leaks anywhere. Can somebody help me?
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85_C10_Sleeper · 03-02-2011, 03:50 AM

have you checked your reservoir level yet?

KaptinK5 · 03-02-2011, 03:53 AM

I did. It was low but after adding brake fluid it didn't help.
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85_C10_Sleeper · 03-02-2011, 09:06 AM

what happens if you just sit and pump the brakes repeatedly?

does the pedal get slightly firmer and then start to get squishy as you slow down?

Jonboy · 03-02-2011, 10:39 AM

Sounds like the seals in the master cylinder are shot. Master cylinders are pretty cheap, I would try that first.

83burban · 03-02-2011, 03:21 PM

If there aren't any leaks at the fittings or the wheels I think its time for a new MC, new fluid throughout, new rubber hoses, and a good bleed job.

Should restore the system to like new.

KaptinK5 · 03-02-2011, 06:35 PM

It has a brake booster. Any chance that could be bad
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Mkcustums · 03-03-2011, 11:18 PM

Quote:

Originally Posted by KaptinK5

It has a brake booster. Any chance that could be bad
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It's not that. You either have a leak, bad seal, or air in the system. Simplest thing would be to top it off, keep it topped off and bleed the entire system and see what happens. Also pull the rear wheels off and drums and check out your wheel cylinders too. When you bleed it remember to do it in the correct order too. RR, LR, RF, then LF.

4pilgrim4 · 03-04-2011, 09:44 PM

I'd put my vote on a bad master cylinder, too, since I've had a couple go that route.

One way to tell is if the fluid level is pretty much to the proper level, it's just about gotta' be the MC. If the MC is empty, then it's leaking somewhere.

Repeated filling and pumping will only saturate your brake linings with brake fluid if a wheel cylinder is bad and render them useless. However, they are likely worn enough to replace anyway - and they're not a big ticket item, nor is a wheel cylinder or a master cylinder - especially if you do your own work.

KaptinK5 · 03-05-2011, 02:21 AM

Thanks for the help. Replacing the master cylinder Sunday. Il
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motornut · 03-09-2011, 08:45 PM

sometimes when the master goes it will leak behind the master/ on the front of the booster sort of a trickle,sometimes paint comes off the booster

03-02-2011, 03:40 AM	#1
KaptinK5 Registered User Join Date: Feb 2011 Location: Luzerne pa Posts: 9	Squishy brakes. Help!? Today I was helping a friend work on his truck. After I left the brakes on my 86 blazer began to seem slightly soft but were still working fine. I later got in my blazer and found that my brakes have no power at all now and go right to the floor. I have no visible leaks anywhere. Can somebody help me? Posted via Mobile Device

03-02-2011, 03:50 AM	#2
85_C10_Sleeper Registered User Join Date: Sep 2010 Location: Riverside, Ca Posts: 141	Re: Squishy brakes. Help!? have you checked your reservoir level yet? __________________ 85 C10 LWB 305ci - 700r4 - 10 bolt - 3:08 gears Collecting parts for a 'mild prerunner"

03-02-2011, 03:53 AM	#3
KaptinK5 Registered User Join Date: Feb 2011 Location: Luzerne pa Posts: 9	Re: Squishy brakes. Help!? I did. It was low but after adding brake fluid it didn't help. Posted via Mobile Device

03-02-2011, 09:06 AM	#4
85_C10_Sleeper Registered User Join Date: Sep 2010 Location: Riverside, Ca Posts: 141	Re: Squishy brakes. Help!? what happens if you just sit and pump the brakes repeatedly? does the pedal get slightly firmer and then start to get squishy as you slow down? __________________ 85 C10 LWB 305ci - 700r4 - 10 bolt - 3:08 gears Collecting parts for a 'mild prerunner"

03-02-2011, 10:39 AM	#5
Jonboy Slots go on anything! Join Date: May 2003 Location: Richardson, TX Posts: 5,957	Re: Squishy brakes. Help!? Sounds like the seals in the master cylinder are shot. Master cylinders are pretty cheap, I would try that first. __________________ 1974 Jimmy- 5.3/4L80e/NP241

03-02-2011, 03:21 PM	#6
83burban Registered User Join Date: Feb 2008 Location: la Posts: 345	Re: Squishy brakes. Help!? If there aren't any leaks at the fittings or the wheels I think its time for a new MC, new fluid throughout, new rubber hoses, and a good bleed job. Should restore the system to like new.

03-02-2011, 06:35 PM	#7
KaptinK5 Registered User Join Date: Feb 2011 Location: Luzerne pa Posts: 9	Re: Squishy brakes. Help!? It has a brake booster. Any chance that could be bad Posted via Mobile Device

03-04-2011, 09:44 PM	#9
4pilgrim4 Registered User Join Date: Jan 2011 Location: Silverdale, WA Posts: 59	Re: Squishy brakes. Help!? I'd put my vote on a bad master cylinder, too, since I've had a couple go that route. One way to tell is if the fluid level is pretty much to the proper level, it's just about gotta' be the MC. If the MC is empty, then it's leaking somewhere. Repeated filling and pumping will only saturate your brake linings with brake fluid if a wheel cylinder is bad and render them useless. However, they are likely worn enough to replace anyway - and they're not a big ticket item, nor is a wheel cylinder or a master cylinder - especially if you do your own work.

03-05-2011, 02:21 AM	#10
KaptinK5 Registered User Join Date: Feb 2011 Location: Luzerne pa Posts: 9	Re: Squishy brakes. Help!? Thanks for the help. Replacing the master cylinder Sunday. Il Posted via Mobile Device

03-09-2011, 08:45 PM	#11
motornut 78K & 79C Jimmys Join Date: Nov 2009 Location: Ottawa Ont CANADA Posts: 7,901	Re: Squishy brakes. Help!? sometimes when the master goes it will leak behind the master/ on the front of the booster sort of a trickle,sometimes paint comes off the booster __________________ John 1978 GMCJimmy4X4-350/203 1979 GMCJimmy4X2-305/350

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