Arrgh , for some reason my front discs have locked on. It's like the master cylinder is not letting the fluid bleed back?
It's a 2 l m cyl with one front port blocked off as I am using a tee piece to feed both discs .
Could it be a problem in the master cylinder???
Tia

Yeah most likely a master cylinder issue
 

Can't be specific as you haven't said what sort of Car you're referring to, so I'll give generic advice...............
De-pressurize both front calipers by opening bleed screws and seeing fluid coming out to verify theyre not blocked.
If wheels now turn, it's a Master Cyl problem....... If wheels still "locked", Calipers are seized and need Overhaul
(assuming wheel bearings aren't seized or o/s tyres hard up against suspension)
note.....If bleed screws "hard" or snap off, release pressure via brake fluid lines.

Sorry BEEVEE
Mk1 escort with 2 L M Cylinder supposedly new little use, new calipers from smcka.
they have been working ok previously which leads me to think the master cyclinder.
Back ones ok. will investigate a little further on the weekend.

............ALSO CHECK that Brake Pedal push-rod isn't over adjusted, or partially influencing Master Cylinder as will happen if pendulum isn't free/jamming or bushes in pendulum pivot "scrunched-up" etc..........a little naughtiness in this area will hold on discs but have little effect at rear !...........sounding more like Master Cyl problem.
********************************************************************************************
WARNING TO ALL.........REGARDLESS OF ZERO MILES OR 100,000 MILES, BRAKE FLUID MUST BE
 
FLUSHED OUT AND RENEWED EVERY TWO YEARS .........AS BRAKE FLUID IS HYGROSCOPIC
 
(ACTS LIKE A SPONGE FOR WATER).....AND WATER in your Brake Fluid is like arsenic in your favourite drink !
 
(Personally, I also replace the fluid in the MC Reservoir once a year in ALL 10 of my cars and CLIENT'S CARS/TRUCKS, as well as Major Flush ea 2 years.......and I have been rewarded with the Master and Wheel Cylinders lasting an average of 20 years, along with RELIABLE BRAKES)

This seems to happen after the motor has been running for a bit. Its like the exhaust is making something hot.
Might wrap the extractors to prove a theory!

1/ Does it have a Master-Vacc (tween the firewall and master Cyl) ?.........take vaccum pipe off to see if that solves
the symptom
2/ What item or items have you changed in the brakes to bring on this problem, no matter how small ?

Ok I took off the booster. And brake tower I left the master cyl and lines connected.
The car moves when cold as the engine runs and engine bay heats up the front brakes start to lock !
I wonder if the extractors are heating the fluid in the rear line and pressurising the master cylinder forcing the brakes on? To prove I may need to block the rears,
Where/ how does everyone route there rear brake line on there 2 l cars?

1/
YOU haven't said what happens when you get front brake "lock-up" and then open just one bleed screw. Does that one now turn ? ...........what does the other caliper/hub do that has NOT have its bleeder loosened off ?
2/ If bleeders are too rusty or too tight for this test, and you don't want to "risk it" at caliper bleeders, relieve pressure by undoing Master Lines one at a time, at Master just a half turn .If f hubs now turn, problem is in master.
3/If master is 100% ok, heat from exhaust expanding the fluid should just flow back to reservoir.
4/You still haven't said what you changed and when, to bring on this problem ?
5/You haven't confirmed MAJOR Brake Fluid FLUSH and refill with CORRECT FLUID that is fresh DOT3 ?
Bernie
 
 

Bernie,
It's a new build so there isn't any working before scenario.
It seems the extractors are throwing out so much heat that the front brake line gets hot and the brakes lock on ,
It's a gradual thing that's affects both calipers and goes away when the car cools down.
I have never known a set of extractors to get that hot. I will look into getting them treated. They are lukey extractors maybe they are a little thin but they are new ??
I would have thought the excess fluid would flow back into the master cylinder and I can free the front discs by breaking the line to relieve pressure so I am confident in my diagnosis. Maybe the master cyl has a problem and could/should be rebuilt as a precaution but that won't solve the excess heat problem that is the root cause.
The extractors have caused the plastic bush on the brake tower to deform.

Btw thanks for the advice and interest in my problem .
Rgds
Emil