fiesta brakes

My wife has an 89-90 G fiesta 1.1 ghia
early this morning she was driving, when the front wheel brakes started to lock on...by the time she had got home the brakes were smoking and jammed on
hard
what would cause this? is this a calliper problem or a master cylinder failure?
Can anyone assist?
many thanks
Bryn
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Bryn wrote:

could be a caliper, but probably a hose coming from the caliper that is messed up inside and holding the pressure on the one wheel....the hose is acting like a one way valve when it breaks inside and lets fluid go one way and not back in... kinda like a check valve?????? find out what wheel is doing this, jack up that side and try to spin the wheel.. if it done move then you take off the tire and crack open the bleeder valve and let the fluid drain out and then spin the wheel.. if it moves then that is the wheel.. also check the caliper pins to see if the caliper can slide back and forth like it should...
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

on
by front wheel brakes, do you mean both front wheels, or just one side?
If both, it is likely that the master cylinder has seized. If this is the case, you can normally get away by unbolting the master cylinder from the brake servo and brake pipes. If it has sezied it is likely the back of the master cylinder will be rusty, and preventing the plunger from returning under spring presure. You can normally get away with cleaning the rust out and putting some silicon grease (normal grease will swell the seals and cause them to fail) in the back.
If only one side has seized it could be any number of things. Could be a seized caliper, a flexi hose that's broken up inside and is acting like a one way valve, pads stuck in caliper
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
its both wheels
its unseized itself and is running fine again....
think i will take the master cylinder apart though and just make sure
cheers for the help!

to
jammed
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Motorsforum.com is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here. All logos and trade names are the property of their respective owners.