Brake Problem?

[grege102]

Hello

Was driving along the other day, went to brake normally and found the brake pedal went soft and traveled a long way down before the brakes came on, luckily they did before my trousers changed colour.

At the time it felt as if fluid was passing the first stage of the master cylinder and I could also hear a short pulsed pump noise which also seemed to come back through the pedal.

Got The car recovered home when getting it off the tow truck noticed the brakes did it again they work but the pedal is soft and goes down a long way before it works.

So decided it was the master cylinder after the recovery guy said that was what it is as well.

So ordered a new one from Lexus at the cost of over £300 and fitted it, used the check plate and the rod needed adjusting less than 1mm, replaced with Lexus fluid, bleed from master cylinder first then rears and fronts, only to find it was no better? bleed with engine running, again no difference?

Has anyone had this happen or heard of anything similar?

I also whipped of all the wheels and checked all the break calipers all are free and working perfectly and lots of meat left on the pads.

The other thing I find strange is that all through out this no lights have come on?

If anyone could shed some light it would be great thanks!

Greg

[steve2006]

A lot of cars these days require pressure bleeding as opposed to the old pump the pedal method, another possibility is air in the ABS block, mine has a bleed nipple on it so check to see if yours has also and bleed this.

Another trick is to clamp off the caliper flexi hoses one at a time then test the pedal movement to eliminate problems in this area.

[grege102]

Hi Steve

There was no bleed screw on the ABS Pump but I also bleed the from the 2 feeds into the ABS unit three times, once with the Engine running as well.

I did do a similar thing to what you suggest, i actually clamped the brake line then removed said calipers one at a time then fitted brake line to a blank block which i drilled and tapped out.

I also checked the calipers for movement on the bench with an air line under light pressure all fine and free and moved back in with the lightest of pressure.

So I am thinking it must be something else?

But thanks for the tips and advice!

Do you know anything about the brake booster unit I keep reading about?

Thanks Greg

[grege102]

Update

This weekend I got a pressure bleed done to the brake system with no difference?

So I am head scratching now, before the pressure bleed I changed the position of the rod in the servo as I was told extending it a small amount would fix it, so tried this in 3 different positions with 3 lots of bleeding.

So the pedal still goes down a long way before the brakes work but if you lift off and pump a the pedal twice the pedal goes firm and the pedal works at the top.

So any suggestions to check would be welcome.

Thanks Greg

[PhilipK]

Do these cars have a Slave cylinder? If so, could the seals have gone in it?

Also, have you tried a complete flush and refill with fresh brake fluid? If there's a compressible contaminant in the fluid (or an air pocket somewhere) it might explain the symptoms?

[aly-g]

If you can pump the pedal to get normal pressure then it's sounds like you have air in the system, my advice would be to bleed the system again farthest wheel to nearest wheel ie n/s rear o/s rear n/s front last o/s front, defiantly air getting in the system, have you checked for any minor leeks? .....

Allan

[grege102]

Thanks for the ideas guys, I will bleed them again, yes genuine fluid has been swapped right out and then some.

The next thing on my list will be to swap the servo! I have just gone offshore for 3 weeks so will report back when done, in the meantime if anyone has any other suggestions please throw them on the table!

Thanks Guys

[Spybey]

Hi Greg,

I'm having exactly the same problem with my IS220d 2006. It's just had a service in which I got them to bleed the brakes through and this has made little/no noticeable difference.

I was thinking of looking at the servo next but if it made no difference to yours I'll give it a miss.

Please keep us informed if you do find the cause.

Thanks Garry

[is200 Newbie]

Has this happened after the service was done ?

[Spybey]

Hi is200 newbie,

No it's been like it for a long while. I think it just got worse very slowly it wasn't really noticeable, until the last 6 months.

Spoke to my garage again today, who say it's not the slide pins as they serviced them while in. They think it is the servo.

At times like these I wish I was a mechanic.