2007 D40 Navara brake issue

[fuzzylogic]

my d40 has had a sinking pedal when running all it's life(300k), hard as a rock when not. Have just accepted it as the norm!

Same for me to be honest, pedal doesn’t quite sink to floor, but slowly sinks to about half way, with constant pressure at idle. Brakes work well is all driving situations, abs works perfectly. The sinking pedal on idle has always done it…

 

[[email protected]]

got this off the net ... a couple of things to look into In a follow-up message, you indicated the brakes were not hot. The most likely cause of a sinking pedal with no external leakage is a faulty brake master cylinder that's leaking internally. Were the brakes hot, we might consider boiling fluid due to moisture contamination or friction material gassing.

Try pressing and holding the pedal (one time, continuously, engine not running - the hard pedal is easier to evaluate) and see if the pedal slowly sinks to the floor. Repeat as needed, pressing softer or harder, and perhaps with the engine running to tempt a symptom recurrence.

If the pedal sinks, this confirms a faulty master cylinder.
Another possibility is that crud at the bottom of the fluid reservoir is preventing consistent take-up of fluid by the cylinder.

 

[Rocky198688]

Ive got some brake fittings that im going to tig up as blanks and fit to the master cylinder tonight. Will let you know how i get on. Cheers

 

[Rocky198688]

So i blocked off both ports of the master cylinder and with the engine running my foot went to the floor. I got another new master cylinder. Bled up brakes and its exactly the same. Solid pedal with engine off and then pedal goes to floor with it running. Im starting to think i may need to get it bled with a scan tool opening the abs valves

 

[[email protected]]

i seem to recall a problem on a non abs model nissan constricted piston in calliper not returning quickly enough to be able to blead properly so hard to.. diagnose these problems

 

[Rocky198688]

Hey guys sorry about the really late reply. So in the end i took it to the dealer and they put it on their brake machine and the brakes passed with ease and when asked about the sinking pedal they told me they all do it. I still cant get my head around that. Although when driving i do feel safe. If i do hit the pix hard my abs goes off before i even get close to the pedal sinking to the floor. But thanks again for all your input and suggestions it was much appreciated