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Question

Ford Ka 2005 Brakes turned spongy

Aug 27, 2017 3:55AM PDT

I bought a used, good condition Ford Ka 2005 1.3l a month ago. It drove nicely and with good, solid brakes, making two or three local area journeys a week and taking me 150 miles Southwest to a wedding and back a fortnight ago on the motorways.

On Wednesday night however, it drove me out fine on an 8 mile trip but, halfway home, I had to brake fairly solidly (not emergency stop) and after that point the brakes felt soft. The pedal would travel halfway before the brakes even came on whereas before that'd be full lock. I tried pumping them but that didn't change the feel. At full depress the brakes were fairly strongly applied, enough that I could safely drive home, but there was little resistance. Parked in the garage, I heard a wheezing sound when the pedal was lifted from the floor.

I contacted the dealer who came over Friday evening to take a look but the brakes were magically working fine and I looked a complete idiot! He invited me to take it to them for a proper investigation, so I drove in yesterday and, when I picked the car up that evening, was told they found nothing wrong. The dealer spent £50 on his mechanic to have a look and gets nothing from me, so it's not in their interests to cover anything up or do a poor job AFAICS, unless there's a bizarre and expensive fault they want to avoid.

So the question is, what can cause my brakes to suddenly go soft and spongy and then clear up after a couple of days without any use? My car appears to be working but can I really trust the brakes?

Incidentally my previous (and first) car was a 2002 Toyota Yaris in perfect condition that generated an engine fault which repeatedly didn't appear when mechanics had a look, until after £300 and 6 mechanics having a look and having different theories, was finally diagnosed as having a rare ECU failure. So I've precedent for obscure and expensive problems! Sad

Discussion is locked

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Clarification Request
How long since the old brake fluid flush and replacement?
Aug 27, 2017 7:14AM PDT

This is something I had to do in harsh climates as eventual water and other contaminants build up. Until I lived in this extreme weather I had never had such done but given the age I have to ask. This is not a firm diagnosis but what it could be. This will clean that system out and they will bleed any air out as well.

The SIMPLEST thing you can check is the brake fluid level. It must be to the fill line.

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Can't be sure, but...
Aug 27, 2017 7:36AM PDT

Fluid is up to Max level. Had a full service March 2015, 15,000 miles ago, and serviced every year. Car is in South East of England, so very temperate. I could buy a tester to investigate? Or is it worth replacing the brake fluid anyway?

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I'd go for the old "bleed" routine.
Aug 27, 2017 8:38AM PDT

Just to be sure there is no air bubble in the system. Sponginess is often caused by this.

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Brakes
Aug 27, 2017 8:47AM PDT

Hi, David; If the brake hydraulic system has been flushed 15K miles ago, it shouldn't need it this soon.
I have had many master cylinders fail as you have described, and then be just fine. The piston inside the master cylinder has two 'cups'. With an older master cylinder, either or both cups can be damaged if the piston goes beyond it's normal amount of travel. This is caused by 'gunk' built up over time. However, since it is working fine now, I'd just keep it in the back of your mind, just in case, and keep an eye on how it's working. One of the classic master cylinder symptoms is when you are sitting in traffic and the brake pedal slowly creeps to the floor. That would be the forward piston cup losing pressure. If the rear cup leaks, the fluid will leak out the rear of the cylinder. btw, never use the brake pedal to bleed or flush the system. Always use a pressure bleeder so the piston cups can't be damaged by the pedal moving the piston too far. Good luck.
Loren (across the pond, in the colonies)

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The old I agree but....
Aug 27, 2017 9:12AM PDT

I've found that when I get something serviced and then there's an issue, they may have messed up.

I agree with you but if it comes back the old bleed is usually the cheap thing to try. Rebuilding or replacing the master cylinder can be a lot more than a bleed job.