Another 60 with a hard brake pedal (1 Viewer)

[bagochips76]

So, I put on a new MC in March or April of this year, bled the system and no problem; brakes function perfectly. Fast forward to summer and warmer weather. All of a sudden, after the motor gets warm the brakes start to engage. More specifically, the front driver side brake appears to be the culprit. I have bled the entire system starting the furthest away from the MC and making my way to the driver side front. It still engages. I have to get out with a 10mm, open the bleed valve, release pressure and then go on about my way. Sometimes, shortly after releasing pressure, it gets hard again and I do the same thing. This time, everything works fine and I go on about my way. The whole thing seems to be heat related. My thought has been that there is an air bubble that expands when it heats up. There is no way that there is still air in the line, after bleeding it so many times. Anybody have any thoughts? I have tested the booster per the FSM and it is fine.

 

[Output Shaft]

New Toyota MC?
If aftermarket, it's in the cross hairs.

 

[3_puppies]

how are the rubber hoses? maybe a flap inside acting as a 1 way valve?

 

[bagochips76]

New Toyota MC?
If aftermarket, it's in the cross hairs.

It is a reman Aisin.

how are the rubber hoses? maybe a flap inside acting as a 1 way valve?

Brand new hoses Paul.

 

[Output Shaft]

Do you think the brakes are really creeping tighter? Or could they be sticking and not releasing? (Sticking calipers).

Try driving the car using only the rear e-brake to stop (in a safe place). See if the fronts lock up if you never use the brake pedal.

Kinda sketchy using just the e-brake on a drive I know.

 

[bagochips76]

They are without a doubt engaging. I think I might pull the MC off and check the length of the rod that engages the MC and adjust as necessary.

 

[3_puppies]

it's odd that it is just 1 of the front not both. I'm thinking if it was a master issue, both fronts would act the same.

 

[gregnash]

Have you rebuilt the calipers in the front or replaced them? Check the pads to see if that side has excessive wear. Also, you could have a pinhole leak in one of the lines that is drawing in air which may contribute to them locking up.

Also, when bleeding the brakes are you doing it the traditional way of having someone pump the pedal or are you using a tool? Has the system been COMPLETELY bleed (going until you see the new fluid)? What process are your using to bleed from furthest to closest? (just to be sure it is the confirmed pattern)

 

[unklwedy]

Make sure vacuum fitting on intake manifold ain't clogged

 

[cruisedeisel]

meh! brakes are a luxury.

 

[cruisermatt]

I would try running it without the booster and see if it still happens. Just unplug all the vacuum lines going into the booster and cap them on the intake so you don't get an intake leak.

meh! brakes are a luxury.

Great contribution to the thread!

 

[feverDream]

+1 on the brake hose-I had the same problem, replaced all the soft hose including the front and rear center and viola!

 

[cruisedeisel]

Its what i do

 

[brownbear]

I would try running it without the booster and see if it still happens. Just unplug all the vacuum lines going into the booster and cap them on the intake so you don't get an intake leak.

I second this advice.

If you had an air leak you would get spongy brakes. Or most certainly when you brake if one side has air the vehicle will not keep straight when braking.

If it's always the same front caliber, it's holding pressure somehow. I also second that there is a block in the line.

You can tell if when you "release" the brakes via a bleeder and fluid squirts out there is pressure. If the same is not happening on the other callipers or rear brake pistons then you have a specific issue holding pressure to the caliber you found holding the pressure.

If either side caliber equally squirts without the brakes depressed you have brakes being activated via the booster or stuck linkage.

New brakes hoses fail too, they don't have to be old to act like a one way valve.

 

[feverDream]

⬆....this

 

[Landpimp]

id say you have a piston sticking in the caliper.