Lots of Bubbles Bleeding Brakes

[galaxy]

Bone stock ‘12, non Brembo GT. This this has a horrible brake pedal. But then every S197 I’ve driven does, thus I didn’t think too much of it. Went to bleed the brakes and air bubbles, air bubbles, air bubbles, from both front calipers.



Doing the bleeding with a Motive pressure bleeder, but ran completely out of fluid before we could let it flush enough to see if the bubbles would go away.



What’s the next play here?? I’ve never ever ran into this. Just let it run and run to see if the bubbles will stop? You can blow through a lot of fluid with the two front calipers quick if you don’t watch it.



Anything else to check? There are no leaks anywhere. Brakes/system work OK considering my disappointment with the brake pedal as it is.

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[Hack]

You could try applying a vacuum to the master cylinder to see if you can get the air out that way. I wonder whether a previous owner ran the master cylinder empty during bleeding or if there's a problem with the master cylinder or the anti-lock systems. The S197s I've owned didn't seem to have poor brakes to me, but I wasn't coming from a S550. The newer Fords have really good brakes in my opinion.

 

[galaxy]

Yea, so I don't have the mx history on the car, so hard to tell. The car was taken care of extremely well though, but shit happens. I got six more bottles of fluid and gonna keep going a while longer to see what happens. Zero bubbles from the rear though.

 

[Cobra Jet]

Yea, so I don't have the mx history on the car, so hard to tell. The car was taken care of extremely well though, but shit happens. I got six more bottles of fluid and gonna keep going a while longer to see what happens. Zero bubbles from the rear though.

A friend of mine with a Vette had similar recent issues when bleeding. It ended up being a bad Brake Master Cyl. He was getting lots of bubbles from the fronts but not from the rears - plus a spongy pedal. He even went as far as replacing the R side front caliper with a new unit - after doing that, went to bleed and was still not only getting bubbles but still had spongy pedal as well.

He rechecked everything - all steel lines from Master Cyl to all calipers were not damaged and fluid was free flowing. Brake booster was recently replaced. Any rubber lines were already newer and flowing properly. No leaks at all from any of the hard line connections, the rubber lines connections OR the F/R calipers.... No leaks either at the Master Cyl or any junctions up front in engine bay. Even checked vacuum pressure from engine to brake booster....

After taking off the Brake Master Cyl, it was found to be bad - he put on a brand new one and no more bubbles or spongy pedal.

 

[galaxy]

Thanks man. Continued homework kinda led in that direction. They're cheap enough I may just throw one on it while we're doing it instead of wasting more and more fluid.

 

[galaxy]

So check this out...

motive pressure bleeder is the culprit. Can’t explain it. There’s no logical or physical reason why the pressure bleeder should cause the bubbles from the front calipers, but...

We bled the brakes the old fashioned way and zero bubbles. Tried the Motive again...bubbles. Went back to old school yet again...no bubbles.

 

[CrashOverride]

Some people don't like reverse bleeding, but I swear by it. Get yourself a handheld sprayer at home depot (Not the 2.5 gallon one, you want the small one). Screw on a female barb connector to the end, attach hose to brake bleeder screw.

1. Siphon out as much old fluid as you can from the master
2. dump clean brake fluid in the sprayer bottle
3. starting with the *closest* brake, push the brake fluid up into the caliper and out through the master cylinder. Bubbles want to go up, not down.

I like to use one of those dollar store "flavor injector" syringes to suck out the brake fluid from the master cylinder. With the long needle, you can get almost all of the fluid out...And it's fine since you're pushing fluid in from the bottom-up.

 

[Hack]

So check this out...

motive pressure bleeder is the culprit. Can’t explain it. There’s no logical or physical reason why the pressure bleeder should cause the bubbles from the front calipers, but...

We bled the brakes the old fashioned way and zero bubbles. Tried the Motive again...bubbles. Went back to old school yet again...no bubbles.

That's a good find. How do the brakes work now?

 

[galaxy]

They work normal. There was no change in pedal feel since car needs brakes anyways, but we were going through the whole car anyways, so I wanted to get the fluid swapped out.

Weird thing is I’ve used this bleeder on other cars, including the 350. Someone (elsewhere) mentioned it could be getting air from around the bleeder fitting or the hose around the fitting, but that just doesn’t make sense. I didn’t do anything different between the Motive and old school. Plus if there wasn’t a leak or something somewhere, a pressurized system should push fluid out, not draw air in. IDK.

 

[FlaGrey]

Great find Galaxy!.. I am having a similar issue that started when I first bled my brakes with the Motive Pressure Bleeder and RBF600.

I wonder if it has anything to do with how gas dissolves into a liquid when it is under pressure much like how beverages are carbonated, but I wouldn't think that just inch pounds of pressure would be able to do this.

Maybe its still the Master, but I'm going to give it a try with a vacuum first at the calipers, before trying to backwards bleed it.

Would pushing the fluid backwards through the system put the air through the ABS system or is that somewhat separate in this case?

 

[galaxy]

So just looking back on this, the only logical explanation is pressure bleeding caused air to get sucked in around the little bleeder thingamabobber when loosened up. Thus there’s no air in the system, just around that port during bleeding. That would mean it’s most likely perfectly fine to pressure bleed, tighten it down, and rock on.
But I guess with bubbles, you wouldn’t know if that’s truly where they are coming from or if it was air in the system. Uuggg.

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