Brand new brake caliper stays locked after releasing brakes?

[Joemile]

Evening lads, I'm at my absolute wit's end and I hope you can help me before I trade this stupid van in.

I've got a 2016 ford transit connect and recently changed pads and discs all round but noticed one of my calipers had a snapped bleed nipple so decided to change the caliper for a brand new one as I like everything to be proper. I even changed the Flexi hose while I was at it.

For some reason after bleeding the caliper up the same way I have with my past 10 vehicles the new caliper doesn't release after pressing the brakes, I'm talking you physically cannot even use the torque of the engine to move the van it's stuck so tightly...

You can releive the caliper by undoing the bleed nipple then fluid shoots out like a jet so I'm assuming this means fluid can get to the caliper but can't get back out.

What on earth could be causing this? It only affects the one brake caliper so it can't be the master cylinder? And the servo still functions when you do a pedal drop test.

The only other thing I can think is ABS pump but why would it still be letting fluid get to the caliper...

Please help me resolve this nightmare!

[metalworker0]

Too much grease on the sliding pins can make sticktion and vacuum, makes them sealed and act like pistons themselves, only use minimal of grease , don't over do it. or when you press the brakes they will be held against the disk and unable to return, because the air in the bore were the slider operate will not be able to get out.

or you've assembled that wire spring clips wrong.

or not likely - the manufacturer of the calipers has put in the seals the wrong way around...as they are wedge shaped, or supplied you with completely dry and un-lubricated calipers.

or there is something wrong with the vacuum brake assist set up ..that i know little about.

it's also possible with an old master cylinder, that when you've bled the brakes, that you've used full travel on the pedal and taken the piston in the master cylinder to a rusty corroded unused spot where it has stuck....i don't use the brake pedal pumping method for that reason on any old vehicle ..if it has done that, and you get it unstuck, the seals in the master cylinder will be trash. i always use Gunsons eezibleed..and it works a treat on the connect - no pumping of pedal involved.
BTW - the design of the master cylinder has no direct connection with the pedal ..pedal presses against a ball ended shaft ..when the pedal is lifted the springs in the master cylinder push the piston back ...so its possible that the pedal may feel normal when the piston is stuck.

BTW, i bought one of those cheap hand vacuum bleeders on ebay ..they work ..but not well enough to get air out of newly installed wheel cylinders or calipers

all the best..mark

[knobby1]

One of you brake flex lines may be falling apart internally...fluid can go one way but not the other.

Lord Knobrot

[Joemile]

One of you brake flex lines may be falling apart internally...fluid can go one way but not the other.

Lord Knobrot

The van is only 5 years old with 58k on the clocks and I changed the Flexi hose for that reason, still have the issue..

[Joemile]

Too much grease on the sliding pins can make sticktion and vacuum, makes them sealed and act like pistons themselves, only use minimal of grease , don't over do it. or when you press the brakes they will be held against the disk and unable to return, because the air in the bore were the slider operate will not be able to get out.

or you've assembled that wire spring clips wrong.

or not likely - the manufacturer of the calipers has put in the seals the wrong way around...as they are wedge shaped, or supplied you with completely dry and un-lubricated calipers.

or there is something wrong with the vacuum brake assist set up ..that i know little about.

it's also possible with an old master cylinder, that when you've bled the brakes, that you've used full travel on the pedal and taken the piston in the master cylinder to a rusty corroded unused spot where it has stuck....i don't use the brake pedal pumping method for that reason on any old vehicle ..if it has done that, and you get it unstuck, the seals in the master cylinder will be trash. i always use Gunsons eezibleed..and it works a treat on the connect - no pumping of pedal involved.
BTW - the design of the master cylinder has no direct connection with the pedal ..pedal presses against a ball ended shaft ..when the pedal is lifted the springs in the master cylinder push the piston back ...so its possible that the pedal may feel normal when the piston is stuck.

BTW, i bought one of those cheap hand vacuum bleeders on ebay ..they work ..but not well enough to get air out of newly installed wheel cylinders or calipers

all the best..mark

Hi mark the van is only 5 years old with 58k on the clocks.

I've fully stripped and rebuilt the caliper so I know that is not the issue and this problem isn't affecting the other side so it cannot be the master cylinder.

I may have to try the ezibleed you mention instead of the traditional method but honestly I can't see a bit of trapped air causing the caliper to stick so hard that it can't even be moved with the force of the engine.

[metalworker0]

Did you get the caliper carriers with the new caliper ..if you didn't ..wire brush the area that is under the stainless shims.

Are the pads new ..if so are they quality and made to the right dimensions.
brake wear indicators I'm told Pads that are fitted with these are fitted one way only.

Did you do the brake bleeding with the carrier and slider bolts loose ..if you did ..the piston could come out crocked and jam.

Think you are misunderstanding the air trapped bit ..not in the caliper but in the sliders - this will lock the wheel.

Newer vehicles have all sorts of gizmos attached to the braking system ..load sensor compensation valves. and god knows what else --all can fail
and there is brake fluid compatibility - if someones put Dot 5 silicone in it ..then it will not be compatible with Dot 3, Dot 4 and Dot 5.1, mixed and could make seals swell and jam.
The dot 5 is a purple colour

Run out of ideas now ..it's all down to the chaps who know how the vac assist works ..but i reckon not as it would effect both sides
How the anti lock works on the connect is also a mystery area for me

all the best..mark

[metalworker0]

Another possible

brand new caliper meant you took out the banjo bolt .

did you install the washer back on this bolt?

Note : some have special "single use" washers

all the best..mark