Ford Transit brake problem, one brake remaining on, intermittent

[JoeB]

Hi

I'm having a problem with one wheel on my Ford Transit. I've only had the problem twice in about two months.

When it happens it feels like the brakes are on.. even when the foot pedal is released. The first time I drove home, about 5km.. when I got home I felt the wheels, the right front wheel was very hot, the other were ok. There were no grinding noises or other metal-on-metal sounds, so I think the pads aren't completely worn.


The following morning the problem was gone... a mystery.

I spoke to a mechanic.. he wasn't really sure to be honest.

So I left it for a few weeks, no problems.


However the problem came back, and with a vengeance. I was driving along and .. bam... problem back. Again it felt like the brakes were on, I was in Dublin town so coulldn't really stop, drove 200m or so, stopped... wheel was slightly hot. I had to continue so I drove about 5km to my destination... the brake disc was gowing red hot!!! Actually glowing... so that's not good.


However, the next morning the problem was gone again.. (remember about a month between incidents).. however the brake disc is badly scored and both discs and pads need to be replaced. I have new ones but I haven't put them on yet as I need to fix the original problem before so that these new ones don't get destroyed..


So what's the problem.????

It hard to see how the pads or disc could be the problem.. the disc is fine and not warped etc, no visible damage (besides new problems due to driving with brake on, scoring etc.. howver the van is back driving now with no new parts yet although a fix is urgently needed)

Ok, so my mechanic recommend replacing the calipers.. these hold the brake pads and there is a seperate one for each front wheel. When I press the foot pedal in the cab, this forces a piston within the Master Cyclinder (under the bonnet), and the Master Cyclinder forces oil down four seperate pipes to each of the wheels... when the pressure is applied to the right front wheel a piston within the calipers is activated, and it pushes on the pads, clamping the disc and braking...


Ok, so since the problem is on one wheel only it seems the calipers might be the problem... however the mechanic has seen the problem before and reckons he has replaced a caliper in similar circumstances, only for the other wheel to display the same problem, replaced another caliper, then the problem came back and it was by replacing the Master Cylinder that the problem was fixed...


Has anyone seen this problem? Should I replace the Master Cylinder?


Cheers Joe

 

[Guest125]

Re: Ford Transit brae problem, one brake remaining on, intermittent

Try replacing the flexible hose to the brake caliper.It could be collapsing internally allowing brake fluid to pass into the caliper but not allowing the fluid to return when the brake pedal is released.

 

[JoeB]

Re: Ford Transit brae problem, one brake remaining on, intermittent

Brilliant, I'll try it.

There are tiny metal pipes coming out of the Master Cylinder (only about 4mm to 5mm diameter), not flexible hoses.. but there might be a flexible join somewhere., if so I'll check it.

You seem to be on the right track, in that the problem seems to be that pressure is applied to each wheel as normal, however it is not released (intermittently) from the problem wheel. But the next morning things are fine, so it is released very slowly it seems.


Would you rule out the master cylinder completely? on the grounds that both front wheels would be equally affected?

Both metal hose pipes for the front wheels come out of the same resevoir on the master cylinder, so could there be an internal feature within the resevoir on the master cylinder that could allow one pipe to be blocked while the other is free?

Or must the problem be with the metal hose, or the caliper?


Calipers are pricey enough... so I'd like to be sure enough... as I say the mechanic has replaced two calipers for a different customer at different times, and then had to replace the master cylinder anyway!!! So a very expensive job.. >1,000 Euro..

 

[mathepac]

Re: Ford Transit brae problem, one brake remaining on, intermittent

I don't want to start a row, but I'd be inclined to disagree with the mechanic. The commonest causes of disc brakes binding IME are :

• a faulty master-cylinder
• a seized brake-caliper piston
• a failed hydraulic seal

AFAIK on commercials the flexible hoses are reinforced with braided metal so should be less likely to collapse than on a regular car, but I'm open to correction.

With only one side seizing my guess would be a failed hydraulic seal (if the piston is seized a new caliper needs to go on).

[broken link removed]

On this twin-piston (twin pot) caliper, the two holes with rust-coloured centres are the pistons and the hydraulic seals are around the outside, copper coloured as they are treated with copper grease.

 

[JoeB]

Re: Ford Transit brae problem, one brake remaining on, intermittent

Hi

God, I don't want to get the mechanic a bad name!. He recommends repacing the caliper.. as the problem is on one wheel only.


I found a dedicated Ford Transit forum and posted the question...

http://fordtransit.org/forum/viewtopic.php?f=5&t=55476

These lads are vey useful, he he, they know loads about Transits for sure.

The consenus seems to be a collasped flexi hose (at the wheel arch)... or maybe a sticky calliper piston although that might cause the problem more often apparently...

Brilliant, no expensive calipers or master cylinders for now.. just a cheap flexi hose!


Mathepac.. how could a faulty seal cause the problem do you think?


Cheers for all replies, much appreciated.

 

[mathepac]

Re: Ford Transit brae problem, one brake remaining on, intermittent

... Mathepac.. how could a faulty seal cause the problem do you think?...

It may twist in the seating jamming the piston out or allow moisture past which can start rust also jamming the piston. The easiest way to damage them is when changing brake-pads, when someone tries to force the pistons back into the calipers with the old pads removed.