Guest Posted January 12, 2001 Share Posted January 12, 2001 Hi Guys,<BR> My brakes need to be bled every month. Where could I have an air leak if it is not leaking any fluid. I have replaced the master cylinder, power booster, one brake caliper (the bleeder broke off), the rubber lines, and the rear wheel cylinders in the last three years.<BR>Should I replace the other caliper? Should I replace the bleeders? What about the combination valve? Could I have bad brake lines? <BR>Thanks in advance<BR>Tomsriv<BR>71 Riviera <p>[This message has been edited by Tomsriv (edited 01-12-2001).] Link to comment Share on other sites More sharing options...
Coley Posted January 13, 2001 Share Posted January 13, 2001 I would suspect the front calipers of letting air in. Is you pedal smooth when stopping hard? If not the rotors should be turned so that the chance of calipers letting air in woulld be nill. I would as a minimum rebuild the calipers at least. Link to comment Share on other sites More sharing options...
Guest Posted January 14, 2001 Share Posted January 14, 2001 I'm not exactly sure what you mean by smooth. Do you mean vibration from out-of-round rotors could let air in. I replaced one rotor and turned the other, but on a quick stop the other day I felt some vibration. The brakes feel like they have more air in them now.<BR> A friend of mine told me that he replaced a master cylinder on a '66 Caprice and about three years later it went bad. Mine is about 1 year old, but I might replace it just to see.<P>Tomsriv Link to comment Share on other sites More sharing options...
brad54 Posted January 15, 2001 Share Posted January 15, 2001 Check the basics. My '54 did the same thing when I replaced the entire brake system. It was sucking air into the line at one of the fittings, yet it wasn't showing a leak. For brake and fuel fittings, there should be absolutely no thread sealant (tape or otherwise) on the threads of the fittings. The flared fittings seat together at the tube--it's not the threads that keep the line sealed. To make sure the lines are sealed, back each fitting off and re-tighten it three or four times to make sure they're seated, but don't torque down on the fittings. Just snug them up. Make the investment in line wrenches if you don't have some already (Craftsman sells a nice set for cheap).<BR>Hope this helps.<BR>brad Link to comment Share on other sites More sharing options...
Guest Posted February 7, 2001 Share Posted February 7, 2001 Well, no luck with the fittings. I am considering the unthinkable, taking it to the shop. Should I keep replacing parts or take it to the mechanic? I have a feeling that the mechanics will waste a lot of time checking the same things I did.<P>Tomsriv<BR>71 Riv Link to comment Share on other sites More sharing options...
Guest Posted February 7, 2001 Share Posted February 7, 2001 Last summer I replaced the shoes on one of my rear brakes and adjusted them properly. When I pressed on the brake (after the installation) it sunk to the floor - tried bleeding and that did not work - and there was no external leak at the wheel cylinder. Replaced the wheel cylinder and that was the problem. So, that was my story.<P>At the "shop" (at least mine) they have some chemical they can put around the fittings to see if there is a leak.It turns to a white power appearance. Seems auto parts stores don't carry it. Link to comment Share on other sites More sharing options...
Guest Posted February 7, 2001 Share Posted February 7, 2001 Theory has it that the residual valves, 2 psi for the disc brakes and 10 psi for the drums, keep just enough pressure in the lines to keep the rubber seals in the calipers and wheel cylinders in firm contact with the bore to keep air from entering the system when the brake pedal is released. The small amount of residual pressure isn't enough to make the brakes drag. You can purchase aftermarket residual valves and plumb them in yourself as very many street rodders do when they modify their entire brake system. Link to comment Share on other sites More sharing options...
Guest Posted February 8, 2001 Share Posted February 8, 2001 Thanks for the ideas.<P>Tomsriv Link to comment Share on other sites More sharing options...
BuickNut Posted February 23, 2001 Share Posted February 23, 2001 Hi..sorry to hear of the problem. Check your rear drums...maybe the auto adjuster isn't working correctly, also check to make sure the drum shoes don't need replaced. Word of advice...replace brake parts in pairs on the same axle. Make sure when you bleed the brakes the axle your bleeding is up in the air..air is lighter than brake fluid and will gravitate to the highest point. The vibration during hard braking is high disc thickness variation (DTV), get both rotors turned at the same reputable place, maybe drums need turned too they may be slightly out of round.....just my opinion.<P>Good luck Link to comment Share on other sites More sharing options...
Guest Posted February 23, 2001 Share Posted February 23, 2001 did you bleed the M/C on the bench before instaling it?<BR><P>------------------<BR>1965 wildcat custom conv Link to comment Share on other sites More sharing options...
Guest Posted February 23, 2001 Share Posted February 23, 2001 I bled the M/C and I replaced the back brakes, but not the wheel cylinders(fairly new). I was going to replace those, but my transmission went out. So I will have to fix the trans, then the brakes and wait two weeks to see if I fixed the problem. <P>Tomsriv Link to comment Share on other sites More sharing options...
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