Avensis Brake Fail Today

[dba]

has anyone had any problems with the avensis and brake failure? i have a 2008 (last of the old shape) 2.2 diesel. i pulled out a junction today and joined some slow moving traffic. went to put on the brakes and nothing. the pedal moved all the way to the floor. it was as if the brakes were not there. i went up the back of a car, luckily i was only doing about 15-20mph.

went to drive off after we exchanged details and the brakes were back.

any advise appreciated. the car was brought froma Toyota main dealer under there approved used car scheme in 2008 and has been serviced by them.

[Fitter]

has anyone had any problems with the avensis and brake failure? i have a 2008 (last of the old shape) 2.2 diesel. i pulled out a junction today and joined some slow moving traffic. went to put on the brakes and nothing. the pedal moved all the way to the floor. it was as if the brakes were not there. i went up the back of a car, luckily i was only doing about 15-20mph.

went to drive off after we exchanged details and the brakes were back.

any advise appreciated. the car was brought froma Toyota main dealer under there approved used car scheme in 2008 and has been serviced by them.

Brake failure like yours, assuming that the brake fluid level is ok, can be the result of seal failure in the master cylinder or a leakage in the system eg from the calipers or pipes or simply air in the system. Occasionally a malfunction in the ABS can occur.

Fitter

[t-spiritpete]

has anyone had any problems with the avensis and brake failure? i have a 2008 (last of the old shape) 2.2 diesel. i pulled out a junction today and joined some slow moving traffic. went to put on the brakes and nothing. the pedal moved all the way to the floor. it was as if the brakes were not there. i went up the back of a car, luckily i was only doing about 15-20mph.

went to drive off after we exchanged details and the brakes were back.

any advise appreciated. the car was brought froma Toyota main dealer under there approved used car scheme in 2008 and has been serviced by them.

Hi mate, firstly i'm glad you were only travelling at a slow speed. I think the first thing to do is get it into the Toyota dealers, how you get it there is a matter for your judgement as you could kill someone driving it there. The master cylinder has a dual system so it would be very unusual if both systems failed unless of course the fluid reservior was empty due to a leakage somewhere but the fact is the brakes came back so I don't think that is the case, worth checking though.

Please let us know the outcome, regards, Pete.

[JDen]

I have had the same problem today. Travelling at 10mph approaching a stationary vehicle when attempting to brake nothing happened and I collided with the rear of the vehicle. 2007 d4d 40,000 miles. After getting out to inspect the damage I tried the brakes. The initial press was very soft and went at least half the travel then subsequently OK. I thought initially that my foot had slipped off the pedal but my passenger assures me that there was no sensation of breaking at all and I shouted out "Nothing is happening"

Has anyone had an answer to this - it's very worrying.

The vehicle is with the local Toyota main dealers for repair c/o the insurance company and I will get them to check it out. It has been serviced by them from new.

[JDen]

I have had the same problem today. Travelling at 10mph approaching a stationary vehicle when attempting to brake nothing happened and I collided with the rear of the vehicle. 2007 d4d 40,000 miles. After getting out to inspect the damage I tried the brakes. The initial press was very soft and went at least half the travel then subsequently OK. I thought initially that my foot had slipped off the pedal but my passenger assures me that there was no sensation of breaking at all and I shouted out "Nothing is happening"

Has anyone had an answer to this - it's very worrying.

The vehicle is with the local Toyota main dealers for repair c/o the insurance company and I will get them to check it out. It has been serviced by them from new.

Just an update. The main dealer could not find a problem. Toyota HQ sent an engineer to check it out - could not find a problem, gave it a clean bill of health. The fact remains that I could not stop and drove into a stationary vehicle. Time for a change I think (reluctantly)

[Konrad C]

I have a theory on the sudden brake loss even though there is no leak.

The pistons in one or more of the callipars has retracted further from the discs further than normal. This can happen for any reason like going over a severe bump or when the brakes are released.

Now those who have ever changed brake pads on a car, know that the pedal has to be pumped to get pads back to close contact to work.

That is why the pedal returned to normal after being pumped.

As I said before there is no leak in the system, but the pads have been displaced. The garage should check the security and movement of the pads and callipars as well as the hydraulic system.

This can happen to any car or motorcycle.

One other issue is that the brake fluid may need to changing! Pumping the brake mixes the air/water with the brake fluid.

I hope this helps.

[Jamesbelfast]

If going over a sever bump in the road would cause a caliper piston to retract more than normal would result in thousnads of road accidents and better still no rally cars would ever finish a stage. So forget the bump theory.

A faulty caliper piston seal can cause a piston to retract further than usual but I have yet to see a faulty caliper repair itself.

Brake fluid naturally absorbs water from the atmosphere over time as brake fluid up to spec DOT4 is hygroscopic - operating the brakes has no effect on this apsect as the brake system is a sealed apart from the breather hole in the master cylinder cap to allow the unimpeded movement of fluid within the reservoir when the master cylinder piston is depressed.

Apart from a leak there are a number of reasons for a brake pedal to drop further than usual and then regain it normal position. Some aspects worth considering are as follows.

1. A faulty flexi-brake hose.

2. A blocked breather hole in the master cylinder cap.

3. And as already said contaminated brake fluid.

4. Dirty or worn seals inside the master cyinder whereby the seals fail to blossom under pressure.

5. A failure with the ABS hydraulic control unit.

When testing brakes many mechanics tend to depress the pedal as hard as possible when in fact applying gentle pressure and watch how far the pedal sinks is a much better test.:)

[pault38]

If going over a sever bump in the road would cause a caliper piston to retract more than normal would result in thousnads of road accidents and better still no rally cars would ever finish a stage. So forget the bump theory.

A faulty caliper piston seal can cause a piston to retract further than usual but I have yet to see a faulty caliper repair itself.

Brake fluid naturally absorbs water from the atmosphere over time as brake fluid up to spec DOT4 is hygroscopic - operating the brakes has no effect on this apsect as the brake system is a sealed apart from the breather hole in the master cylinder cap to allow the unimpeded movement of fluid within the reservoir when the master cylinder piston is depressed.

Apart from a leak there are a number of reasons for a brake pedal to drop further than usual and then regain it normal position. Some aspects worth considering are as follows.

1. A faulty flexi-brake hose.

2. A blocked breather hole in the master cylinder cap.

3. And as already said contaminated brake fluid.

4. Dirty or worn seals inside the master cyinder whereby the seals fail to blossom under pressure.

5. A failure with the ABS hydraulic control unit.

When testing brakes many mechanics tend to depress the pedal as hard as possible when in fact applying gentle pressure and watch how far the pedal sinks is a much better test.:)

have had this a couple of times with mine since new, unsure as to what the problem is but the initial push on the pedal there is very little braking effort but on the second push is rock solid so i always double tap the brakes...think i read on here a while ago that is was something that was known about by mr t and it was to do with the way vacuum is created in a diesel inlet manifold which then assists the brake servo...either way the brakes on my 06 petrol were pin sharp.....the diesel ones arent...bleeding made no difference, new pads have helped a little but still not brilliant

[Konrad C]

If going over a sever bump in the road would cause a caliper piston to retract more than normal would result in thousnads of road accidents and better still no rally cars would ever finish a stage. So forget the bump theory.

A faulty caliper piston seal can cause a piston to retract further than usual but I have yet to see a faulty caliper repair itself.

Brake fluid naturally absorbs water from the atmosphere over time as brake fluid up to spec DOT4 is hygroscopic - operating the brakes has no effect on this apsect as the brake system is a sealed apart from the breather hole in the master cylinder cap to allow the unimpeded movement of fluid within the reservoir when the master cylinder piston is depressed.

Apart from a leak there are a number of reasons for a brake pedal to drop further than usual and then regain it normal position. Some aspects worth considering are as follows.

1. A faulty flexi-brake hose.

2. A blocked breather hole in the master cylinder cap.

3. And as already said contaminated brake fluid.

4. Dirty or worn seals inside the master cyinder whereby the seals fail to blossom under pressure.

5. A failure with the ABS hydraulic control unit.

When testing brakes many mechanics tend to depress the pedal as hard as possible when in fact applying gentle pressure and watch how far the pedal sinks is a much better test.:)

The last post mentioned the difference with petrol and diesel braking systems.

My theory about the pads being knocked further away from the pistons by a very servere bump is possible, but very rare.Example - I was watching World Super bike a few years back, and James Toseland (JT) ran wide at Monza, going off track onto rough stuff. He carried on down the back straight to the next turn, then crashed! The commentator Jamie Witham said that JT had brake failure due to the pads being knocked back when he ran wide. He added 'if JT had realised that and pumped the brakes, he may have not crashed'. Rally cars have better brakes plus the drivers are on the brakes all the tiume, due to the nature of the driving.

Another theory is that the seals could flip. This happened in older Vauxhalls, but thois should not happen now.

I agree about the brake fluid being contaminated and as I mentioned that if there was an airlock in the system, pumping the pedal turns it into tiny bubbles giving a better feel. The single constant press on the pedal may not work as well on diesels - read about sinking brake pedals are normal elsewhere on the forum. I would change brake fluid as a precaution.

The two members who reported having accidents after brake failures, then have normal brakes again need to know what may have caused the problem.

There have been some accidents reported where the driver had the same situation. The police then say that the brakes are fine!

What I am trying to suggest is look at all avenues and not go down one route to find the cause. Every part of the braking system should be checked thoroughly. Safety is paramount!