D2 brake pedal to the floor

Andy P3 said:

Good point James, I blocked up the outlets to the master cylinder with a couple of ball bearings and some brake unions and stood on the pedal with both feet and the pedal didn't move a millimetre, but what you say is a good point as when the Hawkeye bleeds the modulator it sucks the fluid from the master cylinder. I'll have to make up a piece of brake line with some clear tubing to connect in between the inlets and modulator. Won't be till the weekend though.
Andy

Click to expand...

if you have brake pipe flaring kit make some pipes to bypass modulator if thats a good pedal modulator it is ,i have had the pump on the modulator fail and cause a leak before

Yes, I did think about that but I was only going to connect the rear calipers as I only have 10 unions. What's your thoughts on having my unit reconditioned. Some of these places give a lifetime guarantee.
Andy

Should say 10 mm unions.

Why dont you clog the modulator's outlets and try the pedal then to rule out the modulator? the power bleed is working only on the OV circuits, it has nothing to do with the IV circuit which is a straight through the modulator as to connect the master cylinder directly to the calipers, i can't imagine a scenario in which the modulator to ''suck'' air in as if it was a leak there it would push the fluid out but it has two expansion chambers within which if the modulator was empty and got air in them it can take many attempts to bleed also if one of the OV valves within the modulator has failed the fluid will get from the IV circuit into the OV circuit and the pressure damped in the chambers if it's too much air in them.

So if you clog the modulator's outlets and the pedal goes down insist more on the power bleed and if still no joy replace the modulator cos it's fubar, i coloured the normal fluid route from the pedal for one side, the other is the same... the expansion chambers are only for the power circuit in active braking mode to reduce that shudder which you feel when the ABS/TC kicks in they should not affect the pedal if the modulator is OK

In reply to James and Sierrafery instructions I have ruled out the master cylinder and blocked the four outlets. On blocking the four outlets the pedal went solid, I then bled the calipers and the pedal went to the floor. The calipers are new and have no leaks as are all the flexible and copper brake lines.
I've never had problems bleeding brakes before on other vehicles, so what am I doing wrong?
Many thanks for all the help so far.
Andy

Are you sure there is no leak in a flexible hose inside the rubber shield which you can't observe? you should connect the brake lines to the modulatpr one by one while the others are blocked to see which one is causing the problem and insist on that

Will do that tomorrow as long as it doesn't rain, thing is when I force the rear nearside inlet valve on I get a good pedal surely this means the valve is letting by?
Andy

Then IMO there is the problem

That is what I thought, but I tried another modulator and the exact symptoms arose. I couldn't believe both modulators would have the same rear near side inlet valve fault. My next job then is to source a working unit or to have mine refurbished, as I said in an earlier post some places give a lifetime warranty. But how far do they go in the rebuild?
Andy.