Trouble After An Old-Fashioned Brake Bleed

[The Critic]

Vehicle is aznboi24's 2001 Acura CL Type-S, 111,000 miles.

We did a brake fluid flush today as it had not been done in the last three years. I do believe the fluid has been changed before at some point, as it was not nasty enough to be the original fluid.

Originally, we planned to use my Motive Pressure Bleeder with the universal adapter, but there was very little space around the master cylinder area. So, we had to resort to the old-fashioned method of bleeding. We had a copy of the factory service manual and followed the instructions to the T. There is nothing special about the bleeding procedure-- it was your typical pump pedal, hold, open/close screw, release. No factory scan tool needed at all.

We bled the brakes in the order of LF, RF, RR and LR-- as specified by the service manual. It was a strange recommendation as I am used to the traditional RR, LR, RF and LF sequence. We bled the LF and RF calipers around 15 times and the LR and RR calipers around 25 times. We used about 24 ounces of brake fluid-- Acura branded DOT3 fluid from the dealership.

After bleeding, it seems like the pads are engaging slightly faster. You can feel the bite sooner, as in, you do not need to push the pedal down as far. However, the bigger issue is that the firmness of the pedal has been reduced by about 30%. The pedal is no longer has firm as it was prior to the bleed.

We tried rebleeding the brakes multiple times with no improvement. No bubbles are coming out. I whacked the caliper many times with a mallet, but still, no improvement. Basically I have tried just about every trick that exists without any improvement. We never let the master cylinder go dry at any point during the bleed process, nor did we allow the pedal to hit the floor more than a few times.

The brake pedal feel IS perfectly acceptable (very acceptable IMO, if not decent), but it is rather puzzling that it is no longer as firm as it was prior to the bleed.

Does anyone have any ideas? I hope it isn't because we ruined the master cylinder during the bleed.

Thanks.

 

[mechanicx]

I have ran into this when manual bleeding brakes. I think what's happening is that when the brake pedal is stroked and travels to where it would never normally does, the seals contact rougher parts of the cylinder and do not seal as well. One suggestion is to put a block under the brake pedal so it doesn't stroke so far but I haven't tried it. Usually the pedal firms back up on its own over a short period of time but not always.

 

[CharlieJ]

I bled my brakes a couple months ago and have not experienced that.

 

[Craig in Canada]

Originally Posted By: mechanicx
I have ran into this when manual bleeding brakes. I think what's happening is that when the brake pedal is stroked and travels to where it would never normally does, the seals contact rougher parts of the cylinder and do not seal as well. One suggestion is to put a block under the brake pedal so it doesn't stroke so far but I haven't tried it. Usually the pedal firms back up on its own over a short period of time but not always.


This was also my concern when I first read the top post. I use a brick or piece of 2x4 under the brake pedal whenever I bleed. I also check that the thickness is "about right" by testing the pedal before I crack a bleeder. I'll err on the side of a too-short stroke.

 

[Dan55]

As mechanicx has stated it might be the seals in the MC try again with a 2x4 and use a mighty vac this time.

 

[MrBeachcomber]

Given the 111,000 miles on the vehicle, I'd say that the internal seals inside the master cylinder are giving up the ghost under a full pressure bleed. If so, nothing you do is going to prevent them from deteriorating further. (You'll notice the brake pedal slowly settling downward at long stop lights or the brake warning light momentarily illuminating under hard braking.)

IMHO, I'd rebuild/replace the master cylinder so err on the side of safety. YMMV.

 

[CharBaby]

Yes, Honda/Acura require a different bleeding process as Critic has stated. Also as the others have stated that when bleeding brakes the old fashioned way(assistant pressing down on the brake pedal), especially with ABS or as Honda calls it, ALB, you'll need to have something behind the brake pedal so that the pedal doesn't go all the way to the floor while your assistant is pressing the pedal down during the bleeding process. I guess in any vehicle, bleeding the old fash way, one could push down the pedal too far and pop a seal, gasket, o-ring, whatever. That's why I like to use my Miti-Vac.

 

[sciphi]

Could be the parking brake needs adjusting to let the rear brakes engage sooner. See if there's an adjuster somewhere, or drive the car in reverse and stand on the brakes.

Or, did you spill any fluid onto the rotors?

 

[The Critic]

Originally Posted By: sciphi
Could be the parking brake needs adjusting to let the rear brakes engage sooner. See if there's an adjuster somewhere, or drive the car in reverse and stand on the brakes.

Or, did you spill any fluid onto the rotors?

It's 4-wheel disc and the parking brake is a drum in rotor unit. No brake fluid spill onto rotors.

It's troubling to hear that it may be the master cyl. I would've thought that if it was the master the pedal would go completely to the ground, but it's only slightly softer. Someone mentioned that it was possible for me to have screwed up, and that I should try again with a pressure bleeder, but that doesn't seem likely as I can't get any bubbles out.

 

[mechtech2]

Bad or inferior pedal feel after a bleed means bad bleeding to me.

 

[Vikas]

How do they feel with engine off? Is it possible that power assist feel is clouding the issue? If the brakes are grabbing earlier (why is that?) the power assist might be behaving differently than before.

 

[Trav]

Two thoughts.

A bad bleed,you could try just putting a hose on each bleed screw and let it run into a can with no brake pedal action for a few min,let it drain about half the MC out before closing the bleeder.

The calipers were sticking slightly causing them to feel "firmer than normal" and are now moving properly and nothing is wrong at all.

My Expedition usually sits all summer and in the fall the calipers were a little sticky and felt really firm until i did a brake job and used better lube on the pins.
If the seals were damaged i would think the fluid level would go down as it leaked past them into the brake booster or on the carpet.

 

[KrisZ]

If the brake pedal doesn't sink slowly to the floor when pressure is applied, then MC is in good order.

Freed up caliper pins, like Trav mentioned, may be the cause, also look if the caliper pin rubber bushings are in good shape and are not swollen and if the pins have this "snug" feel when trying to slide them out. Loose pins or worn out rubber bushings may cause softer brake pedal feel, and perhaps when the pins were dry and not lubed correctly the problem was masked.

 

[The Critic]

Originally Posted By: Vikas
How do they feel with engine off? Is it possible that power assist feel is clouding the issue? If the brakes are grabbing earlier (why is that?) the power assist might be behaving differently than before.

They feel fine when the car is off, and the pedal does not sink to the ground.

And supposedly the pedal is getting a bit better now, closer to what it was before the bleed. So perhaps something is up with the master cylinder?

Also, the LR caliper bushings are rather distorted and swollen, but they have always been that way.

 

[eljefino]

Originally Posted By: Trav
Two thoughts.

The calipers were sticking slightly causing them to feel "firmer than normal" and are now moving properly and nothing is wrong at all.

My Expedition usually sits all summer and in the fall the calipers were a little sticky and felt really firm until i did a brake job and used better lube on the pins.
If the seals were damaged i would think the fluid level would go down as it leaked past them into the brake booster or on the carpet.


^ This.

Lube the pins and guides and do some hard braking... like the bed-in procedure... so the pads will reseat themselves again.

 

[aznboi24]

I'd also like to add that the RR caliper sounded like it was stuck at the morning drive after the brake bleed. Within a couple miles, it seemed to return to normal.

After driving a few days, everything feels same as before the brake bleed. Brakes engage a bit sooner actually, without the pedal moving as far as before. No complaints here.

 

[chrome]

Another possible area you may have overlooked, is air leakage through the threads on the bleed screws when it was loosened. You can have an airtight seal between the nipple and hose, but air can possibly leak through the threads back into the caliper.

I tend to wind a short length of teflon tape on the threads of the bleed screw to eliminate this.

 

[KrisZ]

Originally Posted By: aznboi24
I'd also like to add that the RR caliper sounded like it was stuck at the morning drive after the brake bleed. Within a couple miles, it seemed to return to normal.

After driving a few days, everything feels same as before the brake bleed. Brakes engage a bit sooner actually, without the pedal moving as far as before. No complaints here.


Then, it seems that the problem had more to do with the new pads breaking in and everything else was done properly, good experience nonetheless

 

[The Critic]

Originally Posted By: KrisZ
Originally Posted By: aznboi24
I'd also like to add that the RR caliper sounded like it was stuck at the morning drive after the brake bleed. Within a couple miles, it seemed to return to normal.

After driving a few days, everything feels same as before the brake bleed. Brakes engage a bit sooner actually, without the pedal moving as far as before. No complaints here.


Then, it seems that the problem had more to do with the new pads breaking in and everything else was done properly, good experience nonetheless

We never installed new pads though.

 

[KrisZ]

Originally Posted By: The Critic
Originally Posted By: KrisZ
Originally Posted By: aznboi24
I'd also like to add that the RR caliper sounded like it was stuck at the morning drive after the brake bleed. Within a couple miles, it seemed to return to normal.

After driving a few days, everything feels same as before the brake bleed. Brakes engage a bit sooner actually, without the pedal moving as far as before. No complaints here.


Then, it seems that the problem had more to do with the new pads breaking in and everything else was done properly, good experience nonetheless

We never installed new pads though.


I missed that, but even old pads still have to wear into the new rotors, it can be still called break in, as grooves and pattern of old rotors will be eliminated by the new rotors.