The 'E' Type Forum

So, having spent some time recently bleeding front and rear calipers, trying to improve the pedal travel (brakes only really operating after a substantial amount of pedal movement), I went to move the car out of the garage today, and the brakes are stuck on. The pedal is completely solid, with only fractional movement possible despite stamping on it a few times.

Bearing in mind this is still fresh from a comprehensive re-build (includes new master cyl assembly/servo etc and was operating prior to my bleeding efforts), can anyone shed some light on how I can release the brakes, and what might have happened?

Hi Richard...see similar topic below...its not uncommom for the reaction valve on the end of the master cylinder to stick....caused by the small piston in the end of the cylinder sticking. .....Steve

Thanks Steve, much appreciated - I've removed the plastic reaction valve end cover and the large diaphragm . The centre pin on the diaphragm appears to be moving the piston, or at least I can push the pin manually against internal spring pressure. Nothing appears to be sticking - this is as far as I can go without losing fluid and getting another round of filling and bleeding. Would you say that it could still be the internal reaction valve piston sticking? Even after pushing as described, my pedal remains locked solid (I've not tried moving the car, but I'm assuming brakes are also still locked on)

From the various other threads I've found, there is also talk of the trap valves on the fluid outlet port of both master and slave cylinders being a possibility for causing a lock up situation such as I have.

I will also try opening bleed nipples and applying pedal pressure - that can wait for another day...

Look at part 10875....the tiny piston in the end of the cylinder body......this piston opetates the reaction valve.....it can get stuck in the out position.........if this is the cause of your brake lock up then by removeing the reaction unit your brakes should release.....but dont press the brake pedal or the tiny piston will fly out and you will lose it....you need to hold a rag over it...press the pedal and it will pop out....clean and rubber grease it and re install...

Ok Steve - I'll see what happens with suitable retention equipment in place. I assume I'll need to re-bleed after this anyway?

Ok, so following the earlier advice, I removed the small piston (I left the end plate loosely attached to prevent the piston from escaping initially). Nothing appeared stuck, but i applied some red grease and re-installed. The hydraulic lock appears to have been released and the car was rolling freely. I still need to start up and test with the servo active, but all appears good now. I am going to assume that it happened due to excessive pumping of the brake pedal with the engine off, so I will avoid that in future.

I don't know how easy it is or even possible to pressure bleed the brakes on the E with 2 reservoirs. Or even vacuum bleed from the bleed nipples. I have found that in the past to be a much better way to bleed brakes than pumping the pedal, which for a while, whilst you raise the pedal, must induce some vacuum into the system which can draw in air.

Jerry......you can use pressure or vacume bleeders on a E type. .....but these are old school cars....and old school bleeding techinuqes work.......the most important point to remember is never release the brake/clutch pedal upward unless the bleed nipples are closed......
1.......open nipple
2.........press pedal down and hold it down
3..........close nipple
4...........release pedal
Repeat above till all air is dismissed........

Steve, IMHO the old school method was a PITA when it was the normal school method.

Back in the '70s I rallied a Cooper S and regularly used the pressure as a simple 1 man operation which worked every time. I had a friend with another S and once we could not get a pedal on his car till we used pressure bleed. It seemed after ages of pedal pumping it was sucking air in somewhere. Pressurising the system with a home made lashup with some tube and a bike pump had it sorted in 10 minutes.

Most importantly, for my mind, pressure bleeding is a perfect 1 man job whilst pedal pumping needs 2 people.

JerryL770 wrote: ↑

Thu Mar 24, 2022 9:33 am

I don't know how easy it is or even possible to pressure bleed the brakes on the E with 2 reservoirs.

http://www.projectetype.com/index.php/t ... ringe.html

Jerry.....I dont know from your post if you were asking how to bleed E type brakes...i explained the "old school" method so there is no confusion as to whats needed.......basically on a system that has no faults air cannot be pulled back into the system if the brake pedal is not released with a nipple open....once you undestand the basic you can easily make it a "one man" operation......just fit a one way valve to the bleed nipple.........Steve

JerryL770 wrote: ↑

Fri Mar 25, 2022 1:21 am

Steve, IMHO the old school method was a PITA when it was the normal school method.

I'm not sure I understand you. Nothing's changed with bleeding brakes since hydraulic brakes were invented.

My syringe trick happens to work for the E Type because it has convenient rubber hoses from the reservoirs, but otherwise it's always been a 2 person job, and always will be.

JerryL770 wrote: ↑

Fri Mar 25, 2022 1:21 am

Steve, IMHO the old school method was a PITA when it was the normal school method.

Most importantly, for my mind, pressure bleeding is a perfect 1 man job whilst pedal pumping needs 2 people.

I don't understand why we are arguing about 2 equally effective methods of brake bleeding.

Use whichever suits you best.

Regards

Now, I'm sorry, I have no intention of having/starting an argument.

I stated : IMHO. I think I'm allowed to express an opinion without it being turned into an argument.

2nd, as I said, pressure bleeding is easily done by one person with no risk of sucking air in. NO argument.

Best wishes to all for using whatever method they prefer.

Cheers, Jerry

Guys, my post was about my brakes being stuck on. I received some advice, acted on it, and freed my brakes.

Now, please don't take this post somewhere it didn't need to go.

I'm unfortunately reviving my old post.

I remain with the issue of brakes sticking on in my car - I haven't driven it, primarily as a result of complete lack of confidence with the brakes. That aside, this is where I am now:

Start engine, brakes are free. A few presses on the pedal and they seize, brake lights permanently on.
Releasing vacuum frees the brakes.

I have removed, polished, lubed, the master cylinder front small piston, several times. This always seems to move freely when I do this, and has never shown signs of sticking. The brakes are then fine until run engine, then they stick again.
I have 2 reaction valves, one from the new MC assembly fitted in 2020 (from SNG but not OE), and one original to the car.
The problem occurs with either reaction valve - both inspected and apparently free of defects. I've messed with stronger springs in these, to no effect.
Servo and slave were rebuilt around 2018 (by others)
MC was new aftermarket part from SNG 2020

So...I'm struggling to diagnose and focus on a specific part now. It would seem to be Servo/slave or MC at fault, but I would welcome any suggestions. Is there specific testing of the Servo that might indicate it as the culprit? Obviously all expensive components to just change without a real indication.

Have a look at part 10877 in the diagram above its a metal flap that operates the small piston....iv had one of these that caused brakes to size up......on mine it looked like it was stamped from sheet metal....curved one side and flat sharp edges the other....I think from memory it was installed with flat side faceing forward....I took it out filed the sharp edges a bit and installed it with rounded edges faceing forwards....it solved the problem....it acts like a flap hinge but was getting stuck.....Worth checking...Steve

Thanks for that suggestion - I can't see how if that plate was getting sticky, removing vacuum would free off the brakes? Am I missing something?

When I had the problem the lever pressed on the piston and pushed it out.....when I released the plastic vac capsual it released.somehow?....Worth you trying....Steve ps ultimately a vacume is holding your brakes on....so what is causing the vacume to hold on and not release?