Land Cruiser brake bleeding.

[gordon stephenson]

Hope this in the correct section,
The brakes on my Land Cruiser 4.2 diesel, have been spongy for a while now,Any way, just fitted new pads all round and even replaced rear discs, I have literally bled "gallons" of fluid thro' the system in every way I know, engine running,engine off,long pedal strokes,short pedal strokes,bled the load limiter on the rear axle, nothing works,pedal till very spongy with a long travel;The system has ABS.
Any idea's anybody.
Desperately yours Gordon,

 

[W4yne]

Hi Gordon,

You have virtually done everything I would have done their. The only thing I can really ask is that a common mistake when bleeding brakes with ABS is that it is imperative when pushing the pistons back into the calipers to make way for the new pads is that you should open the bleed valve and release the pressure that way rather than forcing the pressure back up to the cylinder which has been known to damage the ABS system. Other than that it may possibly be the master cylinder?

 

[Tin Can]

I had a T reg Freelander and just as i was about to trade it in for a 2004 model about 2 years ago i noticed in the week before that the brakes went spongy once or twice but didnt think any more of it. About 2 weeks after i part exchanged it the garage rang me up to ask if i had had any problems with it whilst i owned it as the new owner has said the brakes are dangerous - it turned out the servo was leaking and they replaced it with a 2nd hand one and cured the problem

Hope this might help

Mark

 

[Sphinx]

I would suggest a seal in the servo too.
If you put your foot hard on the brakes (engine running) and hold them on, does the pedal slowly sink to the floor?

 

[shenion]

I find some cars/bikes/clutches don't work well with the pump method of bleeding. I use a vacuum bleeder and it makes a world of difference.

 

[gordon stephenson]

Sphinx,
Yes, foot on brake with engine running and pedal does slowly sink to the floor.Also bleed nipples were opened when pushing back pistons,

 

[gordon stephenson]

I'm still curious, when you say servo leaking, are we meaning on the vacuum side or the fluid seals ie; master cylinder.

 

[shenion]

Servo leak would cause the pedal to be hard.

Sounds like the master cylinder needs to be replaced or rebuilt.

 

[michael1703]

sounds like knackered brake master cylinder seal to me

 

[drjim]

What are the flexi pipes like? If they are old they can bulge a bit too much making the brakes feel soft. Braided hoses all round make a noticeable difference.


Jim

 

[gordon stephenson]

Flexi pipes appear to be OK, Looks like I will have to investigate the master cyl further,

 

[stormin]

Are the calipers the floating type, ie single cylinder and whole caliper moves on bushes fixed to hub?
Sometimes the bushes or caliper wear and cause a sticking rather than free movement due to the off centre loading, leading to a spongy pedal. Check that the caliper floats freely but without any rocking about the bushes. Hard to explain in words. Some calipers can be re-bushed or reamed to suit larger pins.

 

[gordon stephenson]

Hello Stormin,
Front callipers are 4 pot fixed housing, and the rear is 1 pot sliding type, Hand brake by separate shoes inside top-hat shaped discs,

 

[Sphinx]

Sorry, yes I meant brake master cylinder seal.
Although I've not experienced this myself, I've heard of seals being damaged during bleeding; when you push the seal past it's normal travel during bleeding, it can get damaged by the surface of the cylider that's not normally used.

 

[gordon stephenson]

The load proportioning valve on the rear axle has it's own bleed nipple.and 3 brake pipes connected to it, must be pressure in, pressure to rear brakes and what must be a return pipe for the over-spill fluid,Never had one of these units stripped,but the regulator valve must lift and return excess pressure somewhere, The pedal has improved today all on it's own(but still not right) will the system purge any air in the pipes that isn't trapped in a dead end thro' the proportioning valve.