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| | | | Joined: Sep 2019 Posts: 62 'Bolter | | 'Bolter Joined: Sep 2019 Posts: 62 | when first got my restored 1948 3600 chevy, the master cyclinder reservoir was dry. i filled it up and bled the brakes brakes workd fine for about 3 months. i took it out today and went to stop and nothing, right to the floor, looked and master cylinder needed fluid ( a lot). it filled, hand pump a few times to see if i could get air bubbles in MC but nothing. put the cap back on the MC, proceeded to. bleed the brakes and still nothing. looks like a fairly new MC, does this sound like MC failure????
1948 3/4 ton Chevy Pickup
| | | | | Joined: May 2015 Posts: 11,067 Housekeeping (Moderator) Making a Stovebolt Bed & Paint and Body Shop Forums | | Housekeeping (Moderator) Making a Stovebolt Bed & Paint and Body Shop Forums Joined: May 2015 Posts: 11,067 | Did you find a puddle of brake fluid anywhere? It had to go somewhere.
Kevin 1951 Chevy 3100 work truckFollow this saga in Project JournalPhotos 1929 Ford pickup restored from the ground up. | 1929 Ford Special Coupe (First car) Busting rust since the mid-60's If you're smart enough to take it apart, you darn well better be smart enough to put it back together. | | | | | Joined: Sep 2019 Posts: 62 'Bolter | | 'Bolter Joined: Sep 2019 Posts: 62 | that remains a mystery no evidence that i can see.
1948 3/4 ton Chevy Pickup
| | | | | Joined: Mar 2004 Posts: 6,214 'Bolter | | 'Bolter Joined: Mar 2004 Posts: 6,214 | Brake fluid doesn't evaporate, so it's either on the floor, puddled up on the frame somewhere or inside a drum... Mike B  | | | | | Joined: Oct 2018 Posts: 118 'Bolter | | 'Bolter Joined: Oct 2018 Posts: 118 | Does the vehicle have a Hydrovac unit or other vacuum assist ? | | | | | Joined: Sep 2019 Posts: 62 'Bolter | | 'Bolter Joined: Sep 2019 Posts: 62 | no just drump brakes-----
also does not explain why i don't seem to be able to bleed the brakes now. i will check the wheel cylinders , it is my only guess now- leaky wheel cylinder.
1948 3/4 ton Chevy Pickup
| | | | | Joined: Mar 2004 Posts: 6,214 'Bolter | | 'Bolter Joined: Mar 2004 Posts: 6,214 | also does not explain why i don't seem to be able to bleed the brakes now. i will check the wheel cylinders , it is my only guess now- leaky wheel cylinder. Am I understanding you correctly...with a full MC you can't get any fluid to come out of the bleeders. Even if the wheel cylinders are leaking, you should still get fluid out of them when you open the bleeder valve. Are your brake lines all new or recently replaced (steel and rubber)? As you said, it's time to pull all four drums and inspect for leaks... Mike B | | | | | Joined: Sep 2019 Posts: 62 'Bolter | | 'Bolter Joined: Sep 2019 Posts: 62 | no i was able to get fluid out of bleeders, with no air. next stop pulling the drums
1948 3/4 ton Chevy Pickup
| | | | | Joined: Mar 2019 Posts: 1,003 'Bolter | | 'Bolter Joined: Mar 2019 Posts: 1,003 | If the brakes failed and peddle floored, but no fluid loss on the ground. I would look at all 4 corners. What m/c setup do you have? Firewall mounted, under floor mounted? Like previosly stated, fluid went somewhere. If firewall mounted and you have carpet, look under carpet. | | | | | Joined: Sep 2019 Posts: 62 'Bolter | | 'Bolter Joined: Sep 2019 Posts: 62 | it is an under the floor MC, with no visable puddle
1948 3/4 ton Chevy Pickup
| | | | | Joined: Dec 2017 Posts: 1,652 'Bolter | | 'Bolter Joined: Dec 2017 Posts: 1,652 | Sounds like a bad master. Is there a little rubber boot on the back where the rod enters? If so, peel it back and see if its wet.
Mike
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