How can you tell if internal rubber brake hoses are damaged?

[waleed]

I get the occasional soft pedal, and master cylinder, rear drums, and front brakes were done too long ago. Still have plenty of meat, but I get the occasional soft pedal trying to stop. It started to happen about 2 weeks ago. Since then, I started worrying about my brake failing one day, even though ive always been able to get the car to stop. Someone also pointed out it could be the slight rotor warpage as well.

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[Mike]

Is the only symptom is the pedal travel is sometimes excessive, two things that I would consider least likely are internally collapsed brake hose(s) and rotor warpage.

There may be a slight leak that is gradually allowing some brake fluid out and sucks air in.
Look at the fluid level in the master cylinder to see if it has been dropping.
Look at all connections and bleeder screws to find the leak point.
If the replacement master cylinder was remanufactured, there is a reasonably high probability that it is failing.
Another possibility is a failing front wheel bearing, which pushes the caliper piston in as it wobbles–especially during turns.

Internal brake hose problems result in fluid failing to exit the calipers after releasing the brakes.
Since they typically don’t go bad simultaneously, you would feel a pull to one side while braking.
Rotor warpage significant enough to knock the pistons back in , is generally felt as strong pulsation in the brake pedal when braking.

[waleed]

The first two replacement cylinders I used were new, one dorman, one centric. Both leaked at the back so I put the original on, and even then I wasnt getting excessive travel. Then I got a new original and returned it recently because I thought it might have been that. Original back in, I have the same symptom at times. Basically became a pro at replacing these cylinders. I always bleed them out at the front two lines, and never had a problem with air in the system. Lines are all dry, and fluid level is the same.

Could it be a minor vacuum leak? I heard sometimes that causes brakes to feel spongy. What about debris in the system?

[Mike]

No.
A vacuum leak to the booster will cause less power assist resulting in a hard pedal, not a soft pedal.

You’ve had 2 or 3 new recently installed master cylinders leak from the back?
A faulty power booster will cause this.
Read this page:
http://my.cardone.com/techdocs/PT%2050-0001.pdf

If you’ve bled the entire system and used fresh brake fluid, then debris should not be an issue.

If you’ve only been bleeding the master cylinder, you could have trapped air in the system.
While bleeding the master alone often works, it does not always remove all the air from the brake system.

You should also be sure that the rear brakes are in proper adjustment.
Although the self adjusting mechanism is thought by many to maintain proper adjustment, in reality it does a poor to fair job.

The fact that you’ve had several master cylinders leak out the back in a short time, however, points to the power booster.

[waleed]

The other one I had before I put my original one was fine. I returned it and put my old one back on.

The rear fluid at the back of the master cylinder was likely from the two aftermarket ones I had. I did my best to clean the brake fluid in the booster. I know because after I pull it out after a few days, week or two my original one is still dry.

I bled the brakes today and the fronts seemed fine, but rear had some air pockets. I drove the car around a bit and looks like the pedal firmed up.. We did the two front lines, heating the bleeder screw, and opening it, and the backs came off easy. One side seemed to have dirtier fluid on the rear passenger side. Could it have been that I didnt bench bleed one of the master cylinders that there was air pockets? I thought air in the lines would be felt right away, but I could be wrong.

[Mike]

Yes.
The brakes are now working well?

[waleed]

I believe so, but I still keep my eye on it. At times I feel like its not firm as it should could be still but a few people mentioned that It can be the slight warpage on the front causing a somewhat of a soft pedal sometimes. The front pads have about 40% left.

[waleed]

I also noticed that the rear wheel cylinders, centric ones I used are a little smaller than the original, and its meant to fit more cars. I had to use make the adjustor a longer distance to put the brake shoes further to what they should be

[Mike]

That sounds rather odd.
Typically, aftermarket wheel cylinders are going to be the same internal diameter and length as the OE.
Different trim levels of vehicles often use different parts
Makes me wonder if there is a different part number to fit your specific car.
I would look for the manufacturer’s website and verify the part number.
If there’s a cataloguing error, the manufacturer’s website may be the only place that the correct info appears.
A call to the mfgr’s tech support is sometimes in order.

[waleed]

The ones I used were centric premium 13444001, and 13444000 both listed on centrics website. I thought it was odd, but maybe they made pushed back the internal seals a bit to compensate. None of them have leaks. On the other hand, I’ve had to replace a few raybestos ones on this car since most of the leaked and one dorman one which seized. Plus this centric one is made out of cast iron instead of aluminium oe, which I dont mind since I have had the bleeders strip on one before. I really dont plan on keeping this car too long, but still want it to be safe. Most of the steel lines are in very good shape. There was a few areas where it was starting to rust, and I coated it with grease, and sprayed the entire underbody with chainsaw oil to undercoat it.

[Author]

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