Brake problem after changing hoses and rear cylinders

Hoping someone can help me.

I've recently changed all the rubber brakes hoses for stainless steel Hel lines and also replaced the rear drum cylinders.
I bled the entire brake system and the brakes work with the first press of the pedal, but if I lift my foot and press it down again the pedal goes hard but the brakes barely work, lift the pedal again and it seems to work properly.

Basically, if sat on a hill facing down, pumping the pedal should result in a bumpy slow descent, but pumping my brake pedal doesn't do that, it's almost like I have to allow the servo to create a vacuum again.

Am about to bleed the entire system again and hope something works.

What engine do you have?

Nodge68 said:

What engine do you have?

Click to expand...

2001 Td4

If you are loosing the servo assistance then it's likely the vacuum pump or servo at fault. The pedal will come up as boost is lost.
Sometimes a servo diaphragm can fail after the brakes have been bled. This is due the increased pedal movement of the bleeding process.

Nodge68 said:

If you are loosing the servo assistance then it's likely the vacuum pump or servo at fault. The pedal will come up as boost is lost.
Sometimes a servo diaphragm can fail after the brakes have been bled. This is due the increased pedal movement of the bleeding process.

Click to expand...

As above. You can also knacker the master cylinder the same way

I reckon you still have air in the system.
When I replaced the rear cylinders a couple of years ago, I had the same problem, even though I was using a pressure bleed kit.
Found that air was being drawn in past the bleed nipple threads. To solve this issue, I wrapped a few turns of PTFE (Plumbers) tape round the bleed nipple threads-NOT on the tip of the nipple and this sorted it out.
The bleed nipple threads were "Sloppy" in the cylinder when slackened off (Geniuine LR).

Good Luck

Silicone tube, two people and watch for air passing between nipple thread

check the small bore hose that goes over the top of the gear box that comes of the vacuum pump it often wears a hole in it and you loose the vacuum 4mm springs to mind