Several issues you might be facing. The rubber brake hoses could be collapsing internally...no matter how good they look on the outside. If you have no idea how old the hoses are, consider them to be 35 year old originals and replace them. Money well spent.
You could have a caliper piston seal that isn't leaking, but sucking in air...that happened to me. Rebuild or replace all the calipers to eliminate that possibility.
You might have DOT3 brake fluid mixed with DOT5 silicone fluid...they are absolutely not compatible and will give you a very bad pedal...spongy to the max. You will never be able to properly bleed the air out of the system if that's the case. You will often see a cloudy mix in the master cylinder, but not always. If you have DOT3 and 5 mixed, you have to completely...and I mean completely, flush the entire system with fresh fluid and blow it out with compressed air to purge any remnants of the bad mix. Some will say to use an alcohol solution to flush it out before the compressed air. If you replace the hoses it's good to flush everything anyway.
I think your problem is one of those three possibilities.
Gunslinger2010-04-08 13:20:12
