2002 Frontier Crew Cab Brake Issue

[jayqsen]

I rebuilt the calipers on my Frontier, replaced the pads, resurfaced the rotors. After reinstalling the calipers I have not been able to get the front brakes to work at all. I tried to bleed the air out of the system and no fluid comes out of the calipers.

It does have ABS and I have the factory service manual and followed the procedure outlined there. The rear brakes work fine, the ABS light comes on for 2 seconds when I turn the key on and goes off as it should.

It seems that something with the ABS actuator is preventing fluid from going to the calipers.

Any suggestions?

[tech22]

Do you have any petal resistance when you apply the brakes? If not you still have air in the system. I can only assume you followed the service manuel on the repair and if you left the system opened during the calipers rebuild you can rest assured the air is your problem. Have you tryed to pressure bleed the calipers?Try using a hand vacuum pump and that should do it.If you allowed air to get into the ABS actuator it can be vary difficule to get it out. Good luck on your repair .

[jayqsen]

Thanks for the reply. I tried a hand vacuum pump on the calipers and that did not get the air out. Have not tried pressure bleeding ....have no way to do that.

Something else I have noticed....from the secondary piston of the master cylinder to the ABS actuator I have good pressure. That feeds the rear brakes.
From the primary piston of MC to the actuator, weak pressure. Feeds the front brakes.
I pulled the MC apart and can find no visible issues inside. Seals are good because I rebuilt it with a Nissan factory kit 2 years ago....but obviously if weak pressure that has to be part of the problem. According to manual applied pressure needs to be 924 psi measured at bleeder on caliper. 498-555 psi at rear bleeder. I have no gauge to measure, but obviously should be much more pressure coming from primary piston that secondary.....but still cannot "see" anything wrong with MC. Maybe MC is problem?

[tech22]

It's possible that something has blocked the service port. i'am not a big fan of rebuilt brake parts as most are made of alum. The smallist of scratches can cause a failure in the system.Did the brake system work before you rebuilt the calipers? Remember that the brake system will work even if the ABS system has a total failure. So i still believe air in the system is the problem if in fact the brakes were working before the rebuild.Once again do you have petal pressure? Let me know.

[jayqsen]

Prior to doing the work I outlined in my first post, I had an intermittent weak pedal resistance. That's why I rebuilt the master cylinder 2 years ago. But only the primary and secondary piston seals can be replaced. One seal was actually torn and because of that I thought I had solved my intermittent weak pedal problem. But it did not.

However now my problem is solved.....turned out to be the proportioning valve, which is non-serviceable inside the master cylinder.

The clue was the weak pressure coming out of the primary piston port from the MC, but the secondary piston pressure was very powerful.

Put a new MC on and within 10 minutes had all air out and system works great.

[tech22]

That was going to be my next suggestion,the proportioning valve. Glad it all worked out for you.