spongy brakes despite brake bleed several times

[coolj]

Hi All,

I'm going mad here...I'm hoping you guys can help.

I have a 2003 QX4. Since it's been 9 years since I bought the truck, I decided I should probably bleed the brakes.

Unfortunately, the fluid in the reservoir ran out while I was bleeding. I overestimated how many brake strokes I could get before refilling.

Anyway, air obviously got into the master cylinder. So, I restarted the entire process, starting at the left rear then right rear, left front, right front. I made sure to keep the reservoir full. I used a 32 oz bottle of brake fluid until no more air came out of any of the lines. I do all this with a helper and use the depress, open bleeder screw, hold, close bleeder screw process.

However, I still have a brake pedal that goes down further than I know it did before. I've done a complete brake bleed twice now, with the exact same results each time.

My guess is that there's air trapped somewhere that isn't coming out when I bleed.

Anyone have any ideas, please???

[asoomal]

If the M/C was dry, you're going to have to bench bleed M/C.

[Towncivilian]

Since you have a 2003 QX4, there's no load sensing valve or anything else that requires bleeding. You bled the brakes in the proper order. Try readjusting the rear drum brakes if you haven't yet.

Welcome to NICO.

[coolj]

thanks a lot for the info, guys!

what benefit would there be in a bench bleed of the master cylinder versus just re-bleeding all the lines? Wouldn't bleeding all the lines until no bubbles left give you the same result?

[asoomal]

I've been through this before, bench bleeding seemed to fix it.

Sometimes it won't bleed the MC by bleeding by the calipers, the air ends up being trapped in there.

[Pathfound49]

I had the same problem after replacing the brake drum shoes. I bled the rear lines only because i was told that they are separate from the fronts. As townie said, re-adjust the rear brakes. Make them tight. With the rear wheels suspended, they should only spin about half a full rotation(spinning the wheel by hand) after adjustment.

This seemed to fix my problem. About 2000 miles later and still good.

[coolj]

I will try the bench bleed and adjusting the rear brakes. Thanks all for the ideas!

[ARKQX33V6]

Do yourself a good turn and bleed the short distances first, then the longer distances last. That is the brake line distance from the wheel to the M/C. Put a block of wood under the brake pedal to stop the stroke before running out of piston, keeping air out of the lines.

Be sure to bleed all wheels, then cause the ABS system to come on and crawl back and do it all again and this time when you think its all clear of air, brake and keep the brake at pressure, use a block of wood between brake pedal and steering wheel, measure the distance between the pedal and steering wheel, let sit 2 hours then re-measure, did the pedal drop any, if so air in there. Redo.

ABS can come on when driving on gravel, no gravel grease the garage floor, use caution. And be sure of what you are doing.