Brake fade, thinking master cyl.....???

Hey all. I've just finished an engine rebuild on my sons 96' 2.7L, and now I'm trying to check off all the other boxes / nagging items that I've noticed since we bought the truck a few years ago.

Since we've owned it, the brakes have been a little spongy.....and at various times will "fade". It doesn't always show itself. But, when it does......it always happens when you're stopped....foot on the pedal.....for a period of time. It'll fade towards the floor. Pump it, and it's back to stiff.....until it fades again.

Anyhow.....before we ran into the engine trouble a few months back, I had bled the brakes. Fluid looked okay (not terrible.....but not brand new either). Didn't really find any air in the lines.....and bleeding them didn't fix it.

So, I'm thinking maybe master cylinder? They are relatively inexpensive from what I've seen.....so that was going to be my next move. Thoughts?

Also - i have a connector on the side of the reservoir, so I'm thinking that means i DO have ABS? The master cylinders are specific I guess....depending on whether or not the truck has ABS. I can get some pics tonight if that would help.

I'll probably order from RockAuto, but if anyone has a brand recommendation....I'm all ears.

Thanks in advance for any help....

 

I would be surprised if a 96 had ABS. If it does, you have an ABS control module on the passenger side of the engine compartment with all the brake lines routed to it, as well as speed sensors in the front knuckles and rear axle.

But what you are describing could also be a failed brake booster.

The quality of the front brake pads and rotors are a big factor in sponginess. Akebono pads have become to the go to for most of us here.

However, the best thing I can suggest is to get a motiv power bleeder and one of the cheaper MC adaptors. The power bleeder really moves fluid through the system and you can get all that old stuff outta there!

 

In my experience a pedal that drops while sitting is a master cylinder. Also leading that direction as over time the master cylinder will wear a certain way and if you let the pedal go to the floor while bleeding the brakes it could damage the cup seals in it causing it to leak internally

For brand, I would suggest Advics as i've seen them in oem applications then raybestos and centric in that order

 

Thanks, that's really helpful. Rock auto (for the 1996 year model) lists options for both ABS and NON-ABS master cylinders. Mine does have a wire / plug on the side of the reservoir....so I was assuming maybe that is the ABS version?? Here's a link and screenshot from the Rock Auto website. From the pics (and description)....it looks like what I need. Do ya'll agree??

https://www.rockauto.com/en/moreinfo.php?pk=1944970&cc=1278929&pt=1836&jsn=888

 

The wire and plug are the fluid level sensor (the Brake light on the dash will come on with there is low fluid). Please re-read my description of what an ABS truck is equipped with. Or better yet, enter your vin into Toyota's vin decoder / build specs, and see if it was factory installed. It's unlikely that someone would have added it down the line.

 

Ya the reservoir sensor is a level sensor. Easiest way i can think of to check is to check the knuckle for a wire running to the wheel bearing/knuckle area. If you have a wire you have abs. No wire and no abs

 

I had forgotten to update.....but just in case anyone checks or is having a similar issue - it was in fact the master cyl.

I got one from RockAuto (about $80). Bench bleed, install, and bleed all the brakes. No more fade. Thanks for all the advice / help! Cheers!

 

One can see why the term "fade" seems descriptive of your soft pedal, but be careful using that term alone without describing your situation. Brake fade is a well-known term for the loss in braking effectiveness as friction materials (and some brake parts like drums) get hot from repeated, high-intensity use -- as in mountain descents or racing. What you experienced with the old master cylinder is not what one would normally describe as brake fade.

Glad you got it fixed, though!