Another Brake Question - The 1947 - Present Chevrolet & GMC Truck Message Board Network

72Much · 04-25-2011, 09:49 PM

Ok guys. I need some help here. I'm lost as last year's Easter egg. I thought brakes were fairly straight forward and easy to deal with but I stand corrected.

My '72 C-10 is a half ton two wheel drive truck. Original 307/350. Years ago the original rear took an early exit. A rear out a car was put in and made to work for probably 20 years (don't ask me why my dad did that). I located another original 5 lug rear from a '71 truck and replaced it. When I replaced the rear I put in new wheel cylinders on both sides. I then found a donor truck's original power brake brackets, etc. and mounted those. Compliments of O'reilly auto parts I have a new brake booster and master cylinder.

Ok. Here goes. First off I bench bled the new master cylinder. NO AIR in this thing whatsoever. After hooking everything up and attempting to bleed the brakes I'm not getting any pressure to the rear of the truck. I know to work the farthest from the master cylinder forward. I thought the master cylinder may have been bad. So, I'm on my third master cylinder. I worked my way from the rear of the truck to the front breaking the lines at each junction (my dad was in the truck applying pedal each time). I finally got aggravated at not having any pressure and went directly to the master cylinder. While the brake was applied I broke the line loose as it initially exited the master cylinder body for the front brakes. Fluid came out as expected and the pedal began to fall under my dad's foot as it should. I closed it back while the brake was continuously applied to prevent any air from entering the master cylinder. Now on to the pesky back line and back brakes. The same scenario was done and only a few drops would come out with the brake applied and the line completely loosened. How can this be?? I now know that I'm not getting ANY brake fluid to come out of the back of the master cylinder with the brake applied. This is as far as I've gotten. Can someone please advise what I'm doing wrong??

Thanks a ton guys. I'm past ready to cruise my old truck.

04-25-2011, 09:49 PM	#1
72Much Registered User Join Date: Nov 2006 Location: Newbern, Tn. Posts: 36	Another Brake Question Ok guys. I need some help here. I'm lost as last year's Easter egg. I thought brakes were fairly straight forward and easy to deal with but I stand corrected. My '72 C-10 is a half ton two wheel drive truck. Original 307/350. Years ago the original rear took an early exit. A rear out a car was put in and made to work for probably 20 years (don't ask me why my dad did that). I located another original 5 lug rear from a '71 truck and replaced it. When I replaced the rear I put in new wheel cylinders on both sides. I then found a donor truck's original power brake brackets, etc. and mounted those. Compliments of O'reilly auto parts I have a new brake booster and master cylinder. Ok. Here goes. First off I bench bled the new master cylinder. NO AIR in this thing whatsoever. After hooking everything up and attempting to bleed the brakes I'm not getting any pressure to the rear of the truck. I know to work the farthest from the master cylinder forward. I thought the master cylinder may have been bad. So, I'm on my third master cylinder. I worked my way from the rear of the truck to the front breaking the lines at each junction (my dad was in the truck applying pedal each time). I finally got aggravated at not having any pressure and went directly to the master cylinder. While the brake was applied I broke the line loose as it initially exited the master cylinder body for the front brakes. Fluid came out as expected and the pedal began to fall under my dad's foot as it should. I closed it back while the brake was continuously applied to prevent any air from entering the master cylinder. Now on to the pesky back line and back brakes. The same scenario was done and only a few drops would come out with the brake applied and the line completely loosened. How can this be?? I now know that I'm not getting ANY brake fluid to come out of the back of the master cylinder with the brake applied. This is as far as I've gotten. Can someone please advise what I'm doing wrong?? Thanks a ton guys. I'm past ready to cruise my old truck.



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