Master Cylinder using fluid - The 1947 - Present Chevrolet & GMC Truck Message Board Network

skokie · 03-21-2005, 01:31 AM

I was under the hood checking the oil and what not. I get to the master cylinder and I noticed that the front bank was half empty. So I fill it up and a wek later check it again and it is half empty again. I check the tires for a fluid leak. zero. Below the mc itself there is not a drop and the mc is dry. What is going on? Any ideas? That is a new mc.

Tx Firefighter · 03-21-2005, 01:34 AM

It sounds like some air bubbles worked their way to the top then. If it's not going external somewhere, that's what it has to be. Make sure it's not running down the inside of the firewall or into the boster if you have power brakes.

skokie · 03-21-2005, 01:36 AM

Something that I forgot to add that I had forgot was that if you take the cover off of the mc and push the brake pedal down it will squirt fluid out of the front bank.

Tx Firefighter · 03-21-2005, 01:40 AM

Quote:

Originally Posted by skokie

Something that I forgot to add that I had forgot was that if you take the cover off of the mc and push the brake pedal down it will squirt fluid out of the front bank.

Normal.

1-PU70 · 03-21-2005, 09:58 AM

If you have power brakes. Unbolt the master from the booser to see if there is any fluid in there.

skokie · 03-21-2005, 01:06 PM

Quote:

Originally Posted by 1-PU70

If you have power brakes. Unbolt the master from the booser to see if there is any fluid in there.

Will do.

**COBALT** · 03-21-2005, 05:58 PM

Be careful with this. My rear MC reservoir was leaking, and I had fluid emptying out on the exhaust manifold and burning up. At first I couldn't figure out what was happening, because I didn't see any leaks anywhere for the longest time, and I thought it might be an exhaust leak or something since I could smell it. That was until I noticed the paint on the front of the booster was being eaten off by brake fluid, and realized what was going on.

Needless to say I put off fixing it. The short version is that I didn't have any rear brakes because of the leak (no pressure), but the brakes had been this way for so long I didn't realize it, so even if I filled it up the fluid wasn't be used to effectively stop the truck. That means all of my braking was happening in the front. All it took was one hard stop too many, and I blew a wheel cylinder - no brakes. I was going 50 in heavy traffic trying to make a sharp right turn. I barely got stopped in time before hitting some parked cars and causing a major accident.

Find out where that fluid is going, and get it fixed now before you end up in a serious scrape like me.

03-21-2005, 01:31 AM	#1
skokie Registered User Join Date: Oct 2003 Location: San Jose Ca. Posts: 3,354	Master Cylinder using fluid I was under the hood checking the oil and what not. I get to the master cylinder and I noticed that the front bank was half empty. So I fill it up and a wek later check it again and it is half empty again. I check the tires for a fluid leak. zero. Below the mc itself there is not a drop and the mc is dry. What is going on? Any ideas? That is a new mc. __________________ RIP to my son Dylan. 5/17/2002 - 8/18/2018 If you want to know more about rare forms of pediatric cancer or if you want to help fund pediatric cancer research, please check out the website for the non-profit I started. https://slothforpedcancer.org 68 build thread http://67-72chevytrucks.com/vboard/s...d.php?t=223234

03-21-2005, 01:34 AM	#2
Tx Firefighter Watch out for your cornhole ! Join Date: Jun 2003 Location: Azle, Texas Posts: 14,162	It sounds like some air bubbles worked their way to the top then. If it's not going external somewhere, that's what it has to be. Make sure it's not running down the inside of the firewall or into the boster if you have power brakes. __________________ I'm on the Instagram- @Gearhead_Kevin

03-21-2005, 01:36 AM	#3
skokie Registered User Join Date: Oct 2003 Location: San Jose Ca. Posts: 3,354	Something that I forgot to add that I had forgot was that if you take the cover off of the mc and push the brake pedal down it will squirt fluid out of the front bank. __________________ RIP to my son Dylan. 5/17/2002 - 8/18/2018 If you want to know more about rare forms of pediatric cancer or if you want to help fund pediatric cancer research, please check out the website for the non-profit I started. https://slothforpedcancer.org 68 build thread http://67-72chevytrucks.com/vboard/s...d.php?t=223234

03-21-2005, 09:58 AM	#5
1-PU70 Registered User Join Date: Apr 2000 Location: Bradenton, FL Posts: 1,036	If you have power brakes. Unbolt the master from the booser to see if there is any fluid in there. __________________ 1970 CST/10 402,700R4,3:73 posi,AC,PS,PB,TLT,PW,Buckets with heaters

03-21-2005, 05:58 PM	#7
COBALT Senior Member Join Date: Sep 2001 Location: Seattle, WA, USA Posts: 5,817	Be careful with this. My rear MC reservoir was leaking, and I had fluid emptying out on the exhaust manifold and burning up. At first I couldn't figure out what was happening, because I didn't see any leaks anywhere for the longest time, and I thought it might be an exhaust leak or something since I could smell it. That was until I noticed the paint on the front of the booster was being eaten off by brake fluid, and realized what was going on. Needless to say I put off fixing it. The short version is that I didn't have any rear brakes because of the leak (no pressure), but the brakes had been this way for so long I didn't realize it, so even if I filled it up the fluid wasn't be used to effectively stop the truck. That means all of my braking was happening in the front. All it took was one hard stop too many, and I blew a wheel cylinder - no brakes. I was going 50 in heavy traffic trying to make a sharp right turn. I barely got stopped in time before hitting some parked cars and causing a major accident. Find out where that fluid is going, and get it fixed now before you end up in a serious scrape like me. __________________ '69 3/4 ton C20 2wd-350ci/TH400 '69 3/4 ton Custom 20 2wd-350ci/4sp Manual '99 2wd 5.7 Chevy Tahoe Seattle, WA.



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