Brake Pressure

[andy750]

Hi all,

I've just changed my brake fluid on my 2007 avensis 2.2.d4d ,however it seems to have a problem with the pressure on the brake pedal. When i press it the pedal goes down slowly to the floor, but the fluid in the resevoir stays the same. It does not drop. When I pump the pedal it goes firm then it drops to the floor. Would anybody know what this problem could be? Thanks Andy :)

[Bos]

It sounds as though it has not been bled properly and there is still air in the system.

[andy750]

It sounds as though it has not been bled properly and there is still air in the system.

I was changing the fluid and I'm sure no air got in as I was making sure that the bleed nipple was closed off prior to releasing of the pedal which was done by my father.

The pedal was built up to a good firm pedal, I have clampped all the brake hoses on the car around the calipers with no change to the way the pedal feels, and yet still, the pedal fades away.

I'm thinking it maybe the brake master cylinder has anybody had any similar problems, I thinking that the fluid maybe by passing the seals on the master cylinder?

Thanks for the advice andy

[Gooli]

Have a look at this topic : http://www.toyotaownersclub.com/forums/index.php?showtopic=108258

[acetip]

It sounds as though it has not been bled properly and there is still air in the system.

I was changing the fluid and I'm sure no air got in as I was making sure that the bleed nipple was closed off prior to releasing of the pedal which was done by my father.

The pedal was built up to a good firm pedal, I have clampped all the brake hoses on the car around the calipers with no change to the way the pedal feels, and yet still, the pedal fades away.

I'm thinking it maybe the brake master cylinder has anybody had any similar problems, I thinking that the fluid maybe by passing the seals on the master cylinder?

Thanks for the advice andy

you say that you can build up the pedal pressure by pumping the pedal,which in effect compressing (any) air in the ssystem.once the pedal has built up you should be able to keep the pedal high by keeping your foot pressed on the pedal.if you cant keep the pedal high by doing this then suspect the m/cylinder seals.if the pedal is ok then so are the seals.

normaly when bleeding the system at the bleed nipple you close the nipple when the fluid is coming through clear of air.another method is to when pumping pedal is to close the nipple each time the pedal is pushed right down and held there,then open nipple before the next push on pedal.or use a bleeding kit.

[t-spiritpete]

Hi all,

I've just changed my brake fluid on my 2007 avensis 2.2.d4d ,however it seems to have a problem with the pressure on the brake pedal. When i press it the pedal goes down slowly to the floor, but the fluid in the resevoir stays the same. It does not drop. When I pump the pedal it goes firm then it drops to the floor. Would anybody know what this problem could be? Thanks Andy :)

Hi Andy, don't worry that is completely normal with this car as confirmed by my local Toyota dealers.

Pete

[acetip]

Hi all,

I've just changed my brake fluid on my 2007 avensis 2.2.d4d ,however it seems to have a problem with the pressure on the brake pedal. When i press it the pedal goes down slowly to the floor, but the fluid in the resevoir stays the same. It does not drop. When I pump the pedal it goes firm then it drops to the floor. Would anybody know what this problem could be? Thanks Andy :)

Hi Andy, don't worry that is completely normal with this car as confirmed by my local Toyota dealers.

Pete

your saying its ok when you apply your brakes the pedal goes all the way to the floor.

am i missing something here? is it april the first? or is your local MR T situated in a lunitic asylem.how are you supposed stop the car when you have no brake pressure?

[Gooli]

I stated before, don't reinvent the wheel. Have a looksee in this previous thread : http://www.toyotaownersclub.com/forums/index.php?showtopic=108258

[ormi]

that is normal.....

If a large braking force is applied when the vehicle is stationary, the lack of feedback

from the brake system will allow the operator/driver to depress the pedal to the floor,

giving the feeling of lack of brake performance. If the same pedal force were to be

applied by the driver when driving, the brake force realised would be extremely high. The

driver would normally sense this, so such a great pedal force would not be applied. This

is a normal and expected condition. This applies to all Toyota vehicles fitted with A.B.S. &

Electronic Brakeforce Distribution.

[The Cav]

Yes thats the way this type of Brake System on Toyotas works

It Frightened Me To Death when i first noticed it

Like you I Feared the worst

But Be Assured all is OK

[Jamesbelfast]

Sounds like brake assist may be affecting the pedal. The brake system senses the speed and force at which the pedal is depressed coupled with the speed at which the wheels rotate. If the pedal is depressed slowly and the wheels ain't turning then the system knows no either very little or no brake force is required.

[pajjy]

that is normal.....

If a large braking force is applied when the vehicle is stationary, the lack of feedback

from the brake system will allow the operator/driver to depress the pedal to the floor,

giving the feeling of lack of brake performance. If the same pedal force were to be

applied by the driver when driving, the brake force realised would be extremely high. The

driver would normally sense this, so such a great pedal force would not be applied. This

is a normal and expected condition. This applies to all Toyota vehicles fitted with A.B.S. &

Electronic Brakeforce Distribution.

hello ormi

if the brake pedal can be pushed to the floor when car stationary (ignition off?) where does the brake fluid go thats displaced by the the pumping action of the master cylinder when pedal is pushed.after all when bleeding the brake system manualy the car is stationary,and your pumping brake fluid through the system to remove air,then tighten the bleed nipples when this is done.the fluid cant get back into the master cylider reservoir cos of the cheveron type seals.the more of the pressure the tighter the seals push against the master cylinder bore.im just very interested in to understand how this happens.not at all doubting your advice.just a thought if you were decending a long steep hill and have a complete electrical failure,so engine stops so no servo,is there some sort safety back up,cos if pedal goes to the floor,your ability to brake is going to be compromised.

i am sure there must be a simple explanation to this.

[Fitter]

that is normal.....

If a large braking force is applied when the vehicle is stationary, the lack of feedback

from the brake system will allow the operator/driver to depress the pedal to the floor,

giving the feeling of lack of brake performance. If the same pedal force were to be

applied by the driver when driving, the brake force realised would be extremely high. The

driver would normally sense this, so such a great pedal force would not be applied. This

is a normal and expected condition. This applies to all Toyota vehicles fitted with A.B.S. &

Electronic Brakeforce Distribution.

hello ormi

if the brake pedal can be pushed to the floor when car stationary (ignition off?) where does the brake fluid go thats displaced by the the pumping action of the master cylinder when pedal is pushed.after all when bleeding the brake system manualy the car is stationary,and your pumping brake fluid through the system to remove air,then tighten the bleed nipples when this is done.the fluid cant get back into the master cylider reservoir cos of the cheveron type seals.the more of the pressure the tighter the seals push against the master cylinder bore.im just very interested in to understand how this happens.not at all doubting your advice.just a thought if you were decending a long steep hill and have a complete electrical failure,so engine stops so no servo,is there some sort safety back up,cos if pedal goes to the floor,your ability to brake is going to be compromised.

i am sure there must be a simple explanation to this.

The brake ABS system recognises when any wheel is stationary and assumes a skid is in progress. The ABS releases a valve to decrease the pressure in that half of the brake system. The released fluid is stored in the ABS reservoir temporarily. If the pedal is pumped it simply releases more fluid and the pedal goes to the floor. Test the brake with the engine stopped and the ignition off. If the system is ok you will get a hard pedal.

Fitter

[pajjy]

that is normal.....

If a large braking force is applied when the vehicle is stationary, the lack of feedback

from the brake system will allow the operator/driver to depress the pedal to the floor,

giving the feeling of lack of brake performance. If the same pedal force were to be

applied by the driver when driving, the brake force realised would be extremely high. The

driver would normally sense this, so such a great pedal force would not be applied. This

is a normal and expected condition. This applies to all Toyota vehicles fitted with A.B.S. &

Electronic Brakeforce Distribution.

hello ormi

if the brake pedal can be pushed to the floor when car stationary (ignition off?) where does the brake fluid go thats displaced by the the pumping action of the master cylinder when pedal is pushed.after all when bleeding the brake system manualy the car is stationary,and your pumping brake fluid through the system to remove air,then tighten the bleed nipples when this is done.the fluid cant get back into the master cylider reservoir cos of the cheveron type seals.the more of the pressure the tighter the seals push against the master cylinder bore.im just very interested in to understand how this happens.not at all doubting your advice.just a thought if you were decending a long steep hill and have a complete electrical failure,so engine stops so no servo,is there some sort safety back up,cos if pedal goes to the floor,your ability to brake is going to be compromised.

i am sure there must be a simple explanation to this.

The brake ABS system recognises when any wheel is stationary and assumes a skid is in progress. The ABS releases a valve to decrease the pressure in that half of the brake system. The released fluid is stored in the ABS reservoir temporarily. If the pedal is pumped it simply releases more fluid and the pedal goes to the floor. Test the brake with the engine stopped and the ignition off. If the system is ok you will get a hard pedal.

Fitter

hello fitter,nothing was mentioned in the first post wether the ignition was on or off,

thanks for clearing up the point that the ignition has to be on to reproduce the pedal going to the floor effect.have worked on many brake system,vast majority of the before there was abs.so could not get my head around the issue.thanks for the post very helpful.

[acetip]

now fitter has explained whats going on when the pedal reaches the floor and it only occurs when ignition is on now makes sense.could not undestand people saying that it is normal but failing to mention under what conditions this happens.

thanks to fitter for explanation.

sorry for suggesting that a particuer MR T was operating from a mental institution.

[t-spiritpete]

now fitter has explained whats going on when the pedal reaches the floor and it only occurs when ignition is on now makes sense.could not undestand people saying that it is normal but failing to mention under what conditions this happens.

thanks to fitter for explanation.

sorry for suggesting that a particuer MR T was operating from a mental institution.

Hello again Acetip, apology accepted on behalf of myself and Mr T but you do seem to want to jump on people now and again and put them down before you know the full facts. I too have worked on vehicles all my life but this was new to me so I popped along to have a word with a Toyota mechanic friend who explained why and reassured me it was ok ..... hence my comments and advice to Andy in the first place.;)

Pete.

[acetip]

now fitter has explained whats going on when the pedal reaches the floor and it only occurs when ignition is on now makes sense.could not undestand people saying that it is normal but failing to mention under what conditions this happens.

thanks to fitter for explanation.

sorry for suggesting that a particuer MR T was operating from a mental institution.

Hello again Acetip, apology accepted on behalf of myself and Mr T but you do seem to want to jump on people now and again and put them down before you know the full facts. I too have worked on vehicles all my life but this was new to me so I popped along to have a word with a Toyota mechanic friend who explained why and reassured me it was ok ..... hence my comments and advice to Andy in the first place.;)

Pete.

what through me on this,was the fact after one has finished bleeding their brakes,you hop in the driving seat and naturaly test the pedal to see its not, say spongy.why would you turn on the ignition before doing it.anyway its cleared up now.yes i do tend to jump in and that was one of my many new year resolutions that was broken before big ben finished its job.shades of victor meldrew.on my gravestone they will engrave a large mouth with a welly boot hanging out of it.

[paul900]

hi guys just thought id stick my nebber in on this one

i had the same problem with my last car a SAAB 93 TID .. my father has been a mechanic since before i was born (some 32 yrs ago) he said it was because it was a diesel the abs/brake vacum pump works differently so it releases pressure when the car is stationary hence being able to push the pedal to the floor over a period of time .. dont know if this is the same for toyota but my 2.2 D4D does the same thing when stood still but on the move she stops on a tanner !!! as my dad would say