Brakes

[Doc Holiday]

It's been single digit temps in Indiana as of late and I have only had to drive my truck a couple times since 12/22. Today I noticed on the way to work that the brakes need pumped to work anywhere above the floor. A month or so ago I put brand new rotors, calipers and pads on the front and bled them. The master cylinder was low on fluid prior to starting but it never went dry as I added fluid prior, the brakes bled fine with no air when I stopped.


I have it warming in the bay at the firehouse right now in case it is cold related.

Any ideas on a cause?

 

[MichaelOverfield]

It's been single digit temps in Indiana as of late and I have only had to drive my truck a couple times since 12/22. Today I noticed on the way to work that the brakes need pumped to work anywhere above the floor. A month or so ago I put brand new rotors, calipers and pads on the front and bled them. The master cylinder was low on fluid prior to starting but it never went dry as I added fluid prior, the brakes bled fine with no air when I stopped.


I have it warming in the bay at the firehouse right now in case it is cold related.

Any ideas on a cause?

You likely have a leak, or worn seals in the master cylinder, IF it's not air remaining in the system.

 

[Doc Holiday]

We bled the brakes there was very little pressure at bleeders when opened which eventually built back up three or four rounds in to each side as we bled them. I'll try it like this and see what happens

 

[seafish]

Though unlikely, it is certainly possible that you installed the calipers on the wrong side for each wheel, which makes the bleed screw location on the BOTTOM of the caliper, rather then the top where it belongs to properly bleed the caliper and brake lines (...since trapped air rises in a liquid).

You can easily check for this by noting the location of the bleed screw on the caliper. If it is at the top of each caliper, then you have another problem (possible leaking/damaged seals), but if it as the bottom of the caliper, then you will need to swap the calipers from side to side and install them "right side up" in order to get them to bleed properly.

Please know that you will not be the first person to have made this simple mistake!!!

 

[Doc Holiday]

Calipers have been confirmed to be on correct sides

 

[Wayne M.]

It's been single digit temps in Indiana as of late and I have only had to drive my truck a couple times since 12/22. Today I noticed on the way to work that the brakes need pumped to work anywhere above the floor. A month or so ago I put brand new rotors, calipers and pads on the front and bled them. The master cylinder was low on fluid prior to starting but it never went dry as I added fluid prior, the brakes bled fine with no air when I stopped.


I have it warming in the bay at the firehouse right now in case it is cold related.

Any ideas on a cause?

Once you get a pedal, if you hold it, does it drop?

 

[B.G. Smith]

When you bleed the brakes by the pump and dump method which is what I always have used, the combination valve will block off the fluid to the front or back brakes depending on which end you are bleeding. Sounds like this may be what happened and the rear brakes were blocked for a while and then when you drove the truck and used the brakes the combination valve centered itself and the rear lines still have some air. I would open the rear bleeder one at a time and just let the fluid gravity flow out and see if any air comes out. If you end up having to pump the pedal to bleed, do it gently and only go short movement on pedal each time bleeder is opened, not all the way down.. bg

 

[Doc Holiday]

Once you get a pedal, if you hold it, does it drop?

No it doesn’t drop it’s firm once the pedal is there. It was better today but still not right

 

[Doc Holiday]

When you bleed the brakes by the pump and dump method which is what I always have used, the combination valve will block off the fluid to the front or back brakes depending on which end you are bleeding. Sounds like this may be what happened and the rear brakes were blocked for a while and then when you drove the truck and used the brakes the combination valve centered itself and the rear lines still have some air. I would open the rear bleeder one at a time and just let the fluid gravity flow out and see if any air comes out. If you end up having to pump the pedal to bleed, do it gently and only go short movement on pedal each time bleeder is opened, not all the way down.. bg

Just curious why you’re thinking it is rear brake related, can’t confirm it isn’t yet and at this point won’t get back to it until Sunday but I need to be able to logically think through this and you have me curious

 

[B.G. Smith]

Just curious why you’re thinking it is rear brake related, can’t confirm it isn’t yet and at this point won’t get back to it until Sunday but I need to be able to logically think through this and you have me curious

Just thought some air may have entered the rear line when you were bleeding. If the proportioning valve was cutting you off while bleeding the front there may still be some air in the front. Also you were bleeding through the ABS controll. I have read thet if air is in fact in the controller it can be expelled by applying the brakes like in a panic stop while moving on a dirt or gravel surface where the wheels will attempt to lock up. bg

 

[MichaelOverfield]

There is a power bleed function on my Autoenginuity tool to enable a proper flush and brake bleed via the ABS servo and pump. Assuming you didn't use such a feature, I would second trapped air in the system due to insufficient bleed.

 

[cerberusiam]

If you haven't flushed the brake fluid with a power bleeder or just fill and bleed till it is replaced you may now have water causing issues in the brake system. I am assuming you did not have this problem when you originally did the calipers and rotors and it is something new with the cold weather.

When you replaced the old calipers did you open the bleeder when you pushed the cylinders back to release the pads and drain fluid, or, leave them closed and push it back into the system. The former is the correct way plus a fluid replacement, the latter can and will cause problems.

 

[Doc Holiday]

Today we replaced the master cylinder after a sketchy drive to work, we also flushed all the old brake fluid with brand new fluid. Brakes are working great again. Thanks for all of the help.

 

[MichaelOverfield]

Today we replaced the master cylinder after a sketchy drive to work, we also flushed all the old brake fluid with brand new fluid. Brakes are working great again. Thanks for all of the help.

Ahhh, thanks for the follow up. Had a master cylinder do this years ago.. which is why I mentioned it a a possibility. Glad to hear you got it figured out.

 

[Doc Holiday]

Not figured out apparently, its better but not right

 

[MichaelOverfield]

Not figured out apparently, its better but not right

Have you used a computer tool to power bleed the ABS servo motor? If not I would recommend that you do that. I'm pretty sure that function was added for a reason. I have the Autoenginuity Scantool that is able to do this kind of thing. A $30 OBD 2 Scantool won't have these kinds of functions.

 

[Doc Holiday]

Have you used a computer tool to power bleed the ABS servo motor? If not I would recommend that you do that. I'm pretty sure that function was added for a reason. I have the Autoenginuity Scantool that is able to do this kind of thing. A $30 OBD 2 Scantool won't have these kinds of functions.

I have no idea what any of that means.... one more strike against these newer trucks for me. I had like 5 first gens and 1 second gen and they were all far superior trucks to this rolling prima donna.

I'm leaning toward the brake lines being bad or one of the new calipers has failed.

 

[MichaelOverfield]

I have no idea what any of that means.... one more strike against these newer trucks for me. I had like 5 first gens and 1 second gen and they were all far superior trucks to this rolling prima donna.

I'm leaning toward the brake lines being bad or one of the new calipers has failed.

The ABS uses a pump and servo control valve. The proper scan tool is able to put the ABS pump in a mode specically to assist in bleeding air and flushing new fluid through the system. This is done via connection to the OBD 2 connection. I'll see what I can post to further explain this.. I would not be doing any flushing or bleeding on an ABS equipped vehicle with out this capability..

 

[MichaelOverfield]

This article talks about bleeding with ABS:

http://www.stoptech.com/technical-support/technical-white-papers/bleeding-abs-brake-systems

 

[Doc Holiday]

So based on what I read about it ensures I got new fluid through system I'm not sure I need this. I bought a gallon of fluid and watched the fluid color change in the vaccum bleeder we used from a dingy brake fluid to a nice golden colored fluid.

And then there is this statement...

Remember that this is the process for FLUSHING AND FILLING YOUR ENTIRE SYSTEM. If you are only replacing a caliper or performing any other operation where you are simply trying to bleed vapor and/or used fluid from the wheel-end components (like after a hard day of lapping,) you need only to bleed the brakes as you normally would...ala Step #1 above.

There is no reason to cycle the ABS if all you are simply trying to do is get vapor out of the calipers. For this reason, if you flush and fill your system only once per year, the rest of the time you will not need to perform the ABS cycling procedure…or worry about the service tool at all.