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Old 08-14-2007, 11:41 AM   #1
70ChevyCST
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Help:air in front brake lines

Hi guys, Try to make this quick....1970 Chevy LWB pick-up. Still has original front drums. Initial problem: front right brake hanging up causing wheel to heat up/pulling to right. I've replaced master cylinder, front wheel cylinders, front brake hoses, front brake shoes, spring kit, both self adjusters. I'm now battling an endless supply of air into front brake line system. No matter how much I bleed them (pump,pump,pump, push brake pedal down, loosen bleeder, squirt, brake pedal goes to floor, tighten bleeder) I keep getting "milky' brake fluid (air laden) out. When I bleed the rears milky fluid came out at first but then cleared right up and brake pedal stiffened right up. When I bleed fronts...nothing but milky fluid and pedal goes spongy again! What on earth could be wrong? Same fluid used in both front and back...no apparent leaks in lines...One thing that does bother me is that I remember a little copper washer in the past that went between front brake hoses and wheel cylinder...I did not get these with either new parts...but still no leaks there at all...Any feedback surely is appreciated..This truck is wearing my patience as I've been working on this problem since I bought it in late MAY...Thanks guys, Bob
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Old 08-15-2007, 10:43 AM   #2
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Re: Help:air in front brake lines

Looks like you're sucking in air from somewhere. First culprit, of course, could be the connections then the brake cylinders themselves.

May have to dismantle each brake cylinder to check the pistons/seals to make sure they're installed correctly or not damaged.

If you still can't find, you may have to cap off the front lines one side at a time to see if you can isolate to one side or the other.

Also, be sure you have some good quality front brake shoes. I've found some are more grabby than others...
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Old 08-15-2007, 11:32 AM   #3
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Re: Help:air in front brake lines

you need those copper crush washers for the brake hose to cylinder sealing //available at autoparts stores
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Old 08-15-2007, 01:20 PM   #4
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Re: Help:air in front brake lines

Put the copper washers on and gravity bleed them (crack the bleeder and go inside drink a six pack then repeat on other side)
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Old 08-15-2007, 02:07 PM   #5
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Re: Help:air in front brake lines

Hello Bob:
The copper crush washers may solve this, but I would expect some fluid leaking there if air also were getting into the line at that place. Try checking the master cylinder for sucking in and pumping air on the front side and also check at the steel distribution block below the MCyl (proportioning valve maybe?) for any leakage.

Hang in there, take it step by step according to advice given by others, you will get it fixed.

Paul
Prov. 3:5 and 6
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Old 08-15-2007, 03:03 PM   #6
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Re: Help:air in front brake lines

Quote:
Originally Posted by CCCC View Post
Hello Bob:
The copper crush washers may solve this, but I would expect some fluid leaking there if air also were getting into the line at that place. Try checking the master cylinder for sucking in and pumping air on the front side and also check at the steel distribution block below the MCyl (proportioning valve maybe?) for any leakage.

Hang in there, take it step by step according to advice given by others, you will get it fixed.

Paul
Prov. 3:5 and 6
hmmm that's true. You'd think there would be some fluid leaking there. If it's both front brakes it's looking more like mc problem...
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