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Discussion Starter · #1 ·
Hi All, I am pulling my hair out with this one and hope you guys might have some advice so here goes......
I have a GQ with discs front and rear, when it is running and I press hard on the brake pedal it slowly creeps to the floor, when I turn the truck off ( no vacuum) pedal is hard and stays put. I have checked all calipers and rekitted the M/C (which looked mint anyway), there are no leaks and I have bled the brakes properly including the bias valve. any ideas or perhaps do some GQ's just do this????? :confused::headwall:
 

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No...mine doesn`t do that, sounds like there is still air in the system, either that or you do have a small leak some where if your master cyinder is perfect. The pedal should feel softer with engine runing, but it shouldnt go to the floor.
 

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nissan
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Google 'gravity bleeding'. They can be a bitch to bleed properly, and this is the way I found to do it.
Recap MC and bottle after each 'fill' so as to minimize letting moisture in.
 

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nissan gq
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Like all pollies
"Theres some air in there"
 

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nissan
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I had a similar problem , have a look around your brake calipers to see if there is any brake fluid coming out from behind ur inside pads . With mine the seals around the pistons in the calipers were leaking which let air in to the system and would hold a good pedal feel for long
 

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Discussion Starter · #6 ·
Wow I'm defiantly going to try gravity bleeding sounds brilliant, there are absolutely no leaks. My wifes father came around last night and interestingly enough his is identical to mine....... either it is how it is or they both have air in the system.??
 

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nissan patrol
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I'd try bleeding again my mate had to do his twice he swore he had it right the first time but there was still some air in there
 

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Put some pads on my gq yesterday and same thing,,,,haha and im in the automotive game!!all i did was push pistons back and put new pads in ,now pedal when pushed firmly will slowly travel to floor,,,and pedal sometimes feels spongey
Have bled system ,,,no air,,,,am going to grease slider pins to see if it makes any diff
i am wondering if when i pushed pistons back if its feed dirty brake fluid up to the m/cylinder and now seals are by passing ???
 

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nissan patrol
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How does the pedal feel when you pump it with the engine running? Does it feel firm but still sink, or does it feel like you're pushing in a sponge?
If it feels like a sponge, there is air in the system. If it is firm but sinking, it is probably still a master cylinder problem or a leak somewhere. Did the problem happen after doing work on your brakes?
 

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Yeah i can pump it up hard when running and with pressure on the pedal it will slowly sink and then get spongy,,,,it must be by /passing in the m/cylinder ,,,,there are no leaks
Its still braking ok
 
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