Low Brake Power

[nano31]

My is corolla ce110 1998

I have low brake power,for more specific answer I ll give the full story.

It had very good brake power when I brought it 3 yrs ago.

Had to replace master cylinder (MC) due to brake oil leakage but still had good brake power. Replace it with used Japanese MC and servo tank

Then started to fall off the front brake pads even brake pads are 50% and found that brake rotars are worn out and replace it with used Japanese pair. Replaced the front brake calipers/pistons with used jap pair.

Recently I replace rear brake cylinders with pistons brand new Thailand set.

Again had very soft paddle with almost zero brake power and found that front rubber seals are gone and replace the rubber wìth Jap one and removed air paddle feeling improved but still brake very low.

In summary, MC, servo tank, front brake calipers, all four brake pads/liners, rear brake cylinders, front brake roaters replaced.

ABS working fine when required (but hardly any brake power to kik abs in)

Paddle is still somewhat soft as if trapped air but all four wheels fushed to remove any trapped air.

I had low brake since very first brake MC repair, this time it is very low with soft paddle.

What would be the cause? Is it possible to trap air in abs unit and not remove during brake bleed? If so how to remove air from abs unit?

[Magnum]

Did you check the booster?

[Davy]

Was the used Japanese master cylinder overhauled with a repair kit before it was installed?

From your explanation, it looks like your problem started after the installation of the used master cylinder and the servo. So it's likely that the problem is with either the servo or the master pump (or both).

First check if you can spot any visible leaks in the tube that runs from the servo to the intake manifold. It might be audible too if you listen closely. Search the forum on how to check the servo (it has been shared many times before). You can perform those tests yourself and are pretty easy.

Edit:

Just in case you cannot find info on how to test the servo, here it is (direct link to post by Rumesh88):
http://forum.autolanka.com/topic/15409-break-issue/#entry245590

Edited November 8, 2014 by Davy

[luckey007]

Check vacuum lines in the engine bay. Loosen one line will reduce remarkable braking power. Happened to me once.

[nano31]

Each and every components except ABS unit have been replaced/repair including vaccum line. ABS working when hard braking applied yet hardly enough brake power to do so when exceedimg 40kmph!Paddle feeling as if air traped but all four lines had been blead untill no air bubbles appear! I have done google search and found "air traped in ABS unit". But none of local mechanics have no clue including a engineer from Toyota Lanka!

[Rumesh88]

You say that the original master pump was replaced due to an oil leak. Any idea where the leak was? It is normal for master and slave cylinders to begin leaking oil through the worn out washers but in that case it is only a matter of changing the washers but not the cylinders. BTW just take a good look inside the brake oil reservoir tank (preferably with a flashlight) and see if you find black color residues settled on the bottom of the tank. Then ask someone to apply and release the brake pedal while keeping and eye for any movement of oil near the two outlets at the tank bottom and connected to the master pump. It is easier to check this if you use a flash light from the side of the tank.

[nano31]

You say that the original master pump was replaced due to an oil leak. Any idea where the leak was? It is normal for master and slave cylinders to begin leaking oil through the worn out washers but in that case it is only a matter of changing the washers but not the cylinders. BTW just take a good look inside the brake oil reservoir tank (preferably with a flashlight) and see if you find black color residues settled on the bottom of the tank. Then ask someone to apply and release the brake pedal while keeping and eye for any movement of oil near the two outlets at the tank bottom and connected to the master pump. It is easier to check this if you use a flash light from the side of the tank.

Not only the MC but all four wheel cylinders have been replaced, brake oil is very clean.

[Ruslan]

There should be a bleeder plug in ABS unit as well, get all the brake oil out using a Vacuum method, if i remember Correct Pitstop and Toyota Lanka both equipped with these machines.

[Rumesh88]

Not only the MC but all four wheel cylinders have been replaced, brake oil is very clean.

Looks like you have air trapped in the ABS unit. To bleed the unit it has to be connected to a special tool as explained by Ruslan above.

[The Don]

I had a similar issue, and in my case the issue was old brake oil which was saturated with moisture as it happens over time. Replacing the brake fluid sorted that out.

If Ruslan and Rumesh are right, it goes to show the dangers of getting these work done by people who do not understand what they are doing....

[nano31]

Brake paddle is somewhat low still. Need to try vaccum method, it seems the vaccum pump used to bleed brake is a simple hand operated vaccum pump.

[Amila_Silva]

What was the previous brake fluid in the car? Dot 3 or Dot 4?

What is the new fluid you have used?

Was the new brake fluid container was sealed?

On a side note, I don't trust any vacuum pump to bleed the oil. The good old paddling always works fine.

[Rumesh88]

Brake paddle is somewhat low still. Need to try vaccum method, it seems the vaccum pump used to bleed brake is a simple hand operated vaccum pump.

Vacuum pumping alone is not enough (even the use of brake paddle will do just as well) if the ABS unit is NOT provided with a bleeder plug. You will have to get the traction control solenoid valves inside the ABS unit operated through a scan tool to let all the air out. Usually unless ABS unit is replaced during maintenance one should take care not to empty the ABS unit. Almost in all vehicles the brake fluid lines are routed with bends above the unit to prevent this from happening unless you do it deliberately.

[nano31]

Vacuum pumping alone is not enough (even the use of brake paddle will do just as well) if the ABS unit is NOT provided with a bleeder plug. You will have to get the traction control solenoid valves inside the ABS unit operated through a scan tool to let all the air out. Usually unless ABS unit is replaced during maintenance one should take care not to empty the ABS unit. Almost in all vehicles the brake fluid lines are routed with bends above the unit to prevent this from happening unless you do it deliberately.

ABS unit was not emptied deleberately and each and every time the MC also bench blead. Need to try scan tool with vaccum method.

[The Don]

ABS unit was not emptied deleberately and each and every time the MC also bench blead. Need to try scan tool with vaccum method.

This is probably a simple job for a place with the right tools. Rather than messing about, why don't you take it to either Pitstop or the agent and get them to bleed and replace the brake fluid including whats in the ABS pump?

[nano31]

This is probably a simple job for a place with the right tools. Rather than messing about, why don't you take it to either Pitstop or the agent and get them to bleed and replace the brake fluid including whats in the ABS pump?

Thanks for advise , that is what I am going to do

[nano31]

Pistop doesnt have that tool anymore. Did vaccum bleeding and reverse bleeding, some amount of air bubbles came out. Brake power improved. Still seems the initial few inches of brake paddle movement produse very little brake but at the last few inches have good brake power.

[DMendis]

I also have the same problem with my 110. Replaced master pump, cylinders and stuff, but still same. One mechanic said that my break lines are dirty and needs to remove oil, clean the lines and fill with new oil. He says this might happend due to the Garage people some times use the Breakoil pumped out of the lines while replacing break pads. So im going to try the cleaning and see.

[The Don]

I also have the same problem with my 110. Replaced master pump, cylinders and stuff, but still same. One mechanic said that my break lines are dirty and needs to remove oil, clean the lines and fill with new oil. He says this might happend due to the Garage people some times use the Breakoil pumped out of the lines while replacing break pads. So im going to try the cleaning and see.

You need to replace brake fluid every 3-5 years as it absorbs moisture which leads to spongy brakes.

[Rumesh88]

I also have the same problem with my 110. Replaced master pump, cylinders and stuff, but still same. One mechanic said that my break lines are dirty and needs to remove oil, clean the lines and fill with new oil. He says this might happend due to the Garage people some times use the Breakoil pumped out of the lines while replacing break pads. So im going to try the cleaning and see.

Usually there is no need to remove brake oil while changing pads unless it is also due for for a change as mentioned by The Don above. What happens is that when you replace break pads the slave cylinders are compressed to accommodate the new pads. Thus the oil inside the lines flows back to the reservoir. There is nothing wrong doing this as long as oil is not due for a change.

[Ruslan]

Pistop doesnt have that tool anymore. Did vaccum bleeding and reverse bleeding, some amount of air bubbles came out. Brake power improved. Still seems the initial few inches of brake paddle movement produse very little brake but at the last few inches have good brake power.

Did you bled the ABS unit as well?

[nano31]

Did you bled the ABS unit as well?

Does it have bleeding plug? What we did was reverse bleeding and vaccum bleeding

[Ruslan]

Does it have bleeding plug? What we did was reverse bleeding and vaccum bleeding

Some units comes with it, usually closed with rubber cap. like Rumesh said you have to bleed it with scanner plugged. that way you need to open all the actuators to release oil in all the lines.

[The Don]

Sounds like only the agent has the tool required now. This is a bit surprising because since 2007 third parties were allowed to build tools to link with any automotive interface and even perform tasks like key programing. This has opened up some security loopholes but was done to support independent garages. Surely somebody else has the tools to do this properly.

[nano31]

After all I wanted to replace vacuum pump as there is nothing to change except ABS unit and brake lines which seems ok.

Gotta one Rs 4000/=.

All Brake issues are gone

I should have done it early...