At a loss with this

[Tilly-1]

I have a Lexus GS 300 L reg ( I know old donkey ) had the car for 3 years now, this problem has been there from day 1 well... morning 1

When I drive the car from stone cold I hardly have any brakes at all, if I leave it running for a couple of minutes, then move off and brake it improves , by the time I get off our estate the brakes are fully operational, I can drive round all day with no problems. The car has been into a couple of garages, they tell me the brakes are fine, it has passed 3 MOT's,
It's a " morning " thing, anyone heard of this before? what could it be? got to get it sorted out because I want to sell it.
Lynn

 

[stevie1]

my only thinking is that the pads could be sooking up moisture from the air and thus causing crappy brakes until you have used them a few times
as for selling it you could be sneaky and once you know someone is coming to see it take it for a run

 

[Tilly-1]

Thanks stevie1, hmmm I had had new quality pads fitted, two callipers ( they used to stick)Oh and worn disc's have been replaced.( badly worn)

This problem occurs even in the summer months, the car is parked up the drive, it gets the early morning sun, plus when it pours down or I go through a lake the brakes work just fine.

Oh you made me laugh with "run out in the car before someone comes to see it" you know what? I couldn't sleep at night if I did that, I wish I wasn't so honest..... but I am lol
Lynn

 

[Dellsmp]

Sounds more like a problem with the servo assistance for the brakes, this uses engine vacuum to boost the force available at the brake pedal.
There may be a valve in the system that allows air in when the engine is switched off to prevent 'overrun' and this could be sticking when cold.
Ask a garage to check out the servo system and if possible get them to take the car in for a rest overnight so 'they can experience' the problem.

 

[Tilly-1]

Thanks DELLSMP,I will ask them to check that out, I told the last garage they needed to take the car in the night before, he said" I'll leave it to stand for a few hours" of course..... the braked were fine when he checked them.
Lynn

 

[mikeddavies]

It could be that the vacuum hose to the servo is collapsing internally (considering the age of the car) and restricting the build up of vacuum in the servo - once established it would take a long time to decay. Try pumping the brakes (with the engine off) until the servo assist stops - pedal goes very hard - and see if it takes a while to re-establish the servo assist when the engine is started - hold the brake pedal down and you should feel the servo come "live". I would tend to just replace the servo hose - with correct vacuum hose.

MikeD

 

[Tilly-1]

Thanks Mike, OK... I pumped the pedal until it went hard, started the engine with foot to the floor, the pedal pushed up straight away.
Lynn

 

[ratm]

I have to have my say on this one. The sticking servo valve sounds like the best bet. Make sure that the vacuum pump hasn't popped the seal and is drawing oil/air in. Also check in case you're getting oil or fluid contamination on your pads or discs overnight. Does it always get hard when you pump it?

 

[Tilly-1]

Oh Ian I thought you weren't talking to me lol

Thanks, I'm getting it over the pit tomorrow.


YES! roflmao
Lynn