MrMoose

Yeah, that's not great, but won't cause a pedal-to-the-floor issue. Only thing I can think of is if one of your pads was dragging, overheated the caliper, and boiled the fluid? But that would only happen after a bit of driving and it would feel fine when it cooled down.

All that said, you should take brake loss very seriously, and if there's any uncertainty about whether you've fixed the issue or not talk to a real pro.

dgjks6

Put the correct rotor on the L rear

Started to detail the R caliper and found this.



Guess I'm going to learn how to rebuild a caliper...

Petza914

There are stainless caliper pistons available from somewhere - I'd use those so you don't have to deal with this again. Driving any car in the crappy salt belt tears up so much of it.

MrMoose

I'm not sure that's too big a problem, honestly. Looks like it just corroded a bit where the piston contacted the pads, maybe some differential metal electrolysis thing going on. The piston sealing surface is sealed off under those rubber boots: that's what rides on the caliper seals and it should be chromed and won't corrode.

Here's what I'd do: carefuly remove the dust covers by prying up the outside edge (try not to damage them, but if you do they're available for purchase) and inspect the bore and sealing surface for any corrosion. If those looks good, lay a block of wood or something down the middle of the caliper (so the pistons can't pop out) and carefully apply compressed air to the fluid input hole of the caliper: a tire inflator with a plastic inflator nozzle will usually work for this. You want to see if the pistons are seized or not, the wood down the middle will keep them from moving too far outward and popping out.

If the pistons can move in and out and the bores look good I'd probably call them okay, just clean off the piston end a bit and slap a Porsche anti-vibration damper on each one. Do not let any dirt or corrosion flakes get down along the sealing surface when the dust covers are removed or that can damage the seal.

Vibration damper, check to make sure it's the right one for your car: https://www.pelicanparts.com/More_In...SVSI=4902&fs=0 Maybe these would've helped prevent the corrosion as well, I dunno.

This is all stuff you've gotta do to rebuild the calipers anyway, so might as well inspect them first before you start buying parts.

dgjks6

How do I know what size I have without pulling them sort?

The rebuild kit from Pelican says 28 and 30 but all this pistons look the same size. And there are no dampers on the rear. They did compress compress in fine.

But the corrosion is a layer of what looks like paint flaking off. But I guess you are right. Should no be able to get past the sealing ring.

I agree with you plan to take apart and inspect.

MrMoose

Dunno about the sizes, honestly. I'd guess that's piston diameter but I'm not sure.

There were originally supposed to be dampers on the front and rear pistons. They're not really necessary, TBH, and a lot of times they just don't get replaced when the brakes are done. Basically I think they've just got a sticky coating on them to prevent pad vibration, and you can do the same thing with anti-squeal spray on the back of the pads. But I figured in your case they might help a bit if the pistons were getting corroded by the pads.

Or maybe it's not corrosion, maybe it's just paint and anti-squeal spray stuck to the piston surface.

Ohio Performance

Your rears are 28/30mm pistons and your fronts are 36/44mm.

dgjks6

Thanks for all the help.

dgjks6

Ok let's start again.

New pads all around
New rotors
New master cylinder.
New fluid and bled.

And no difference.
Here's the symptoms
Pedal feels normal half way down and slows the car. Then after a second pedal goes all the way to the floor and no brakes.
I do hear a grinding noise when I hit the brakes - kind of like the first drive after a wash and there is some rust on the rotors.

Basically exactly like it was before.

Any thoughts besides towing to a dealer?

MrMoose

Huh. At this point I don't even know how that's still possible, honestly. I'm looking at the brake diagrams and there's just nowhere for pressure to go assuming the MC is working properly. I mean, the ABS module is kind of a black box, but even if that goes bad you should still have pressure from the MC at the calipers. I'm stumped.

You're sure you don't have a fluid leak somewhere? Absolutely 100% sure?

Wayne Smith

I had an F150 that did this because of a problem with the ABS module.

There is a special method with the PIWIS (I'm not sure if the Durametric will do this or not) that will bleed the ABS unit. Or you may need to replace it.

Good luck and please let us know the resolution.

dgjks6

Thanks Moose. I do appreciate all the help. No leaks
I tested with the pressure bleeder. I only pump to 10-12 psi. It holds pressure forever. Or at least 20-30 minutes.

Thanks Wayne. I hope not. This car is killing me. 6 years didn't miss a beat. This year can't catch a break.

Ok here is the plan step by step

1-list the car for sale for $50,000 with no brakes

Or

1-hook up scanner and look for codes
2-bleed the ABS system - I have a launch x431 ProS mini that says it will do it...
3-re bleed all 4 corners
4-rebuild the calipers 1 at a time

Bruce In Philly

2009 C2S 177K miles

Vacuum pump failure?

https://rennlist.com/forums/997-foru...acement-2.html

Peace
Bruce in Philly (now Atlanta)

dgjks6

Interesting. But mine is really soft not hard.
But it is rusty

I may change it for the heck of it.

Throwing money and parts at a problem without a diagnosis always works out well.

Bruce In Philly

The rust is scary but may have nothing to do with a failure of the pump. Just to be safe, I used rust remover, some sand paper, and painted it... I think that was a worthless effort as the metal is apparently very thick... so noted by other posters.

Peace
Bruce in Philly (now Atlanta)