97widerider

Just had my 4 calipers completely rebuilt by GM retired mechanic. I now see that the driver's rear outer bleeder screw is not working. Fluid was oozing out initially under brake pressure, more like seeping, but now it opens up as if the bleeder valve is open.... shoots right out. It is snug tight, not stripped. I have used a few different bleeders to include the ones that were taken off and they all do this. Obviously I have a problem with the seat inside the valve chamber.

I totally understand that this is something beyond the standard new pistons, collars, o rings, springs etc. Unless tested under pressure how would anyone know. I think this may be the culprit for my calipers getting into the mess they were.

Is this fixable without buying a new caliper again? I would hate to just waste the rebuilt caliper because of a dang bleeder screw problem.

I also noticed there is a capped off valve on the same caliper half but on the bottom. What if I put the cap on the bad valve and the bleeder on the bottom? At least each half of the rear caliper would have a bleeder valve but I also understand air rises and it might be impossible to get the air out of the caliper.



Any help is appreciated.

'75

Yeah, it needs a bleeder on the top to get the air out of both halves.

mikem350

Maybe a "speed bleeder" would thread in and seal....hopefully others will chime in

7T1vette

If it requires machining to repair it, it would be less trouble and expense to just replace that caliper.

PAmotorman

http://shop.advanceautoparts.com/p/d...3960/5012856-P

gungatim

they used to sell a bleeder repair kit, have seen them on many an old caliper. not sure if they still do, and have never used one but know they existed at one time...

hugie82

Harbor Freight sells a reverse drill bit set. It works very good. You drill a pilot hole and keep going bigger until it backs out. If it all goes south, you always have the option of using the bleeder repair kit in the HELP section of any auto parts store.

mr.beachcomber

Since you've already tried re-using your old bleeder valves, I think that you've ruled out that the leaking bleeder valve is the wrong size. One of the problems I've experienced over the years with the cast iron C2-C3 calipers is rust developing in the threaded area preventing the bleeder valve from completely seating.

Try using a correct-sized bottom tap to clean/refresh the threads all the way to the bottom on the hole for the bleeder valve. It's important to clean the very bottom threads so that the bleeder valve seats itself and blocks off the internal fluid channel to the pistons. Try turning the tap a 1/4 turn at a time with lubricant and then reversing it to clear any debris. After re-tapping the hole, if your bleeder valve feels loose (sometimes the rust is the only thing holding the bleeder valve tight), try wrapping a small length of Teflon tape around the bleeder valve's threads before re-inserting it.

Personally, I prefer stainless steel bleeder valves for use with cast iron as the SS will cut through any cast iron rust. Just don't cross-thread them because they will destroy the cast iron threads requiring drilling a new hole and larger diameter bleed valve. YMMV.

Hope this helps!

REELAV8R

Rust in the bottom of the threads sounds like a likely cause. If that doesn't work I would try bleeding the brakes initially as it is then cap that leaky bleeder. That may keep it from leaking. Then when you need to bleed the brakes, cap comes off and bleeder goes back on for bleeding purposes.

toobroketoretire

If the bleeder screw got over-tightened the casting cracked and there's no fixing it.