Gu 2.8 brake issue

[Prawn]

Hey all. Im Nick. Just got my self a 2.8 gu pootrol loving it. One issue i have is the brakes go rock solid after 1-2 pumps. Seen some posts on here its a vacuum issue booster issue. Now i have replaced the booster and some lines that looked rough but still have the same issue. Ive pulled lines off from the vac and it has suction not sure how much its meant to have. And ive tested all lines back to the booster and they all have vacuum. Where should i go from here?
Thanks

[MB]

Welcome aboard Nick mate, congratulations on your new rig. Sorry can’t help on your brakes problem not too savvy there, maybe a slave cylinder issue? I did have vacuum line leak a while ago that created rock solid feel at fully depressed. Is yours rock solid at full pedal out? Hopefully a guru will be along soon mate.


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[Prawn]

Welcome aboard Nick mate, congratulations on your new rig. Sorry can’t help on your brakes problem not too savvy there, maybe a slave cylinder issue? I did have vacuum line leak a while ago that created rock solid feel at fully depressed. Is yours rock solid at full pedal out? Hopefully a guru will be along soon mate.


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Hey mate

I press the brake pedal and its normal then release and press again it goes solid and i release again and try and press it does not budge. If i keep the pressure on it and push real hard it slowly starts heading to the floor. But thats with the engine running.

[MB]

My vac line leak experience was small enough to get home as you mention with engine running/heel and toe revs up. As mentioned, not too savvy on this but is it worth dumping all brake fluid for fresh too? Threads on here have seen discussed fluid contamination but not sure if that’s your issue or not mate?


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[Prawn]

Changed all brake fluid. I will be rebuilding calipers and new disks on it next week. Not sure if that eould affect it tho.

[BillsGU]

Did you bleed the LPV above the diff? Many brake issues result from a faulty / seized LPV or one that has not been bled properly - or not been bled at all.

[Prawn]

Dont even know what that is haha thanks ill look into that tomorrow and see how i go.
Anything i should look out for?

[BillsGU]

OK. It's the load proporting valve that is bolted to the chassis and operated by a lever that connects by a spring to the rear axle housing. It proportions rear braking depending on the load in the rear of the Patrol. It is at the highest point of the rear brakes and air can accumulate there causing the piston in the valve to pit and seize.

When you bleed it, if a lot of muck comes out, it is usually an indication that it has not been bled before (or for a long time). It is in a pain of a spot to get to - which is why it is often overlooked. Take the valve off and check that it moves freely.

[Prawn]

Thanks. Bled the valve it was pretty clean and no air bubles. But the unit itsself is caked with muck.

[BillsGU]

The outside doesn't matter as long as the valve moves freely. Unfortunately it looks as though this was not the problem.