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Good day everyone, I am have a serious problem with the brakes in my D22 frontier, over the past few months I noticed the pedal slowly sinking to the floor and about a week ago I got so bad that the pedal would go straight to the floor and the van would barely stop. I put in a repair kit in the master cylinder, bench bled, then bled all 5 bleeder valves starting with the furthest from the master cylinder. After all that same problem. So I bought a new master cylinder and repeat the process and same problem, pedal straight to the floor and little to no brakes. I've checked for leaks and couldn't find any, calipers, wheels cylinder and lines all dry. I desperately need some help.

Master cylinder was loaded and from what source? I have seen new masters with bad seals as they were sitting too long. Cylinder was good and not worn so a new seal kit was what was required.

U bled it alone?
It needs a proper bleed, with one person pumping and another at the hubs, fid it to get the air out and not suck it back in.

Are the breaks pads /discs moving freely and not stuck down?
Is the fluid level dropping?
If not then most likely is master seals.

Dave wrote:Master cylinder was loaded and from what source? I have seen new masters with bad seals as they were sitting too long. Cylinder was good and not worn so a new seal kit was what was required.

Thanks for the reply, I bought it from Autorama in El Socorro and we bleed it outside the van. I will try changing the seals.

sMASH wrote:U bled it alone?
It needs a proper bleed, with one person pumping and another at the hubs, fid it to get the air out and not suck it back in.

Are the breaks pads /discs moving freely and not stuck down?
Is the fluid level dropping?
If not then most likely is master seals.

Thank you for the reply. We bleed the master cylinder outside the van and 2 of us bleed the brakes. One person pumping the pedal and the other opening and closing the bleeder valves. Also it has new wheel cylinders in the rear and recently installed a seal kit in the calipers, it doesn't loose any brake fluid and the tires spin freely. I would hate to think the new master cylinder bad .

Check your booster? Strange enough malfunctioning booster would cause the master cylinder not to be bled properly. If you force feed brakes fluid thru cylinder and open bleeders as directed, you would be successful.

vivnb wrote:

sMASH wrote:U bled it alone?
It needs a proper bleed, with one person pumping and another at the hubs, fid it to get the air out and not suck it back in.

Are the breaks pads /discs moving freely and not stuck down?
Is the fluid level dropping?
If not then most likely is master seals.

Thank you for the reply. We bleed the master cylinder outside the van and 2 of us bleed the brakes. One person pumping the pedal and the other opening and closing the bleeder valves. Also it has new wheel cylinders in the rear and recently installed a seal kit in the calipers, it doesn't loose any brake fluid and the tires spin freely. I would hate to think the new master cylinder bad .

There is a 1 way valve in the vacuum line for the booster. Check to see if that is bad and needs to get replaced.

how i know it to be. booster is for power assist, master cylinder is for fluid pressure and pedal feel.