Brakes Brakes Brakes (or lack of)

[NJV6]

Brake pedal is a bit sus.... Goes to the floor a little to readily and also takes a moment to react.

2nd pump it works pretty goodly

I have replaced the rear discs and new pads. Both lock up on demand evenly and no dragging when jacked up and spun.

Fronts, new pads, one front not working as well as it should - will give it a clean out. Got a WOF with it like this - tester must have been having a good day or just happened to pump the brakes before it went on the rollers!

New master cylinder as I though it must have been bypassing.

Still same issue, pedal almost goes to the floor and brakes work better on second pump.

There is no air in the system, checked and checked again.

Any ideas cos I am fresh out! Whats in the brake booster? I wouldn't have thought it would make a difference.

[Lynx]

Generally if the booster is shot, it would have a hard pedal. It doesnt have a rear prop. valve by anychance does it?

Cheers Daniel

[tweake]

check wheel bearings. if they are loose it pushes pads back out which means there is more travel before the brakes start to work.

[UBZ]

Id block off each line and try bleeding individually.can also help to lift the rear of the truck.

I had the same issue on my Zuk , bleed and bleed and bleed to no avail. was sure I had no air in the system. lifted the rear of the truck and a big bubble of air came out. must have been trapped in the proportioning valve.

[kbushnz]

Also check your hoses, I had one go soft and would expand. Almost ruptured.
It was one that went from the body to the chassis. Little short sucker.

[DieselBoy]

Its gotta be air man. All it can be. Brakes don't pump up for any other reason, other than if something is forcing a piston back into the caliper once you have finished braking.

We get all sorts of random issues with disc conversions on the rear of SJ413's. The pump up pedal is air. You have to bleed and bleed and bleed them sometimes. Then there is the catch where the bleed nipple catches on the bump stop on full flex and forces the piston back into the caliper and you have to pump the brakes 3 times before you push the piston back out. So thats something to check. can't imagine anything on a Pajero that would make that happen though.

You might have water in your brake fluid (its hydrascopic) which might have turned into a gas pocket (air) when you got your brakes really hot last time. The fluid only needs to reach 100degrees for that to happen.

If it passed a WOF like that, maybe your being paranoid?? The difference between the work ute and the Pajero maybe??

[NJV6]

Cheers for all ya answers! Woohoo - TECH!!!

Generally if the booster is shot, it would have a hard pedal. It doesnt have a rear prop. valve by anychance does it?

Pedal is not hard with engine on at all. It does get slightly harder with each quick pump when enigne is at idle from not enough vacuum being produced

SWB Paj's don't have valves in the rear no

check wheel bearings. if they are loose it pushes pads back out which means there is more travel before the brakes start to work.

Yea that was my 1st thing I checked, usually a good way to know when to tighten wheel bearings

Id block off each line and try bleeding individually.can also help to lift the rear of the truck.

I had the same issue on my Zuk , bleed and bleed and bleed to no avail. was sure I had no air in the system. lifted the rear of the truck and a big bubble of air came out. must have been trapped in the proportioning valve.

I'll try that tomorrow.

Also check your hoses, I had one go soft and would expand. Almost ruptured.
It was one that went from the body to the chassis. Little short sucker.

I thought about that but then thought if it was swelling then surely with the pressure these come under it would have just gone pop!

Its gotta be air man. All it can be. Brakes don't pump up for any other reason, other than if something is forcing a piston back into the caliper once you have finished braking.

We get all sorts of random issues with disc conversions on the rear of SJ413's. The pump up pedal is air. You have to bleed and bleed and bleed them sometimes. Then there is the catch where the bleed nipple catches on the bump stop on full flex and forces the piston back into the caliper and you have to pump the brakes 3 times before you push the piston back out. So thats something to check. can't imagine anything on a Pajero that would make that happen though.

You might have water in your brake fluid (its hydrascopic) which might have turned into a gas pocket (air) when you got your brakes really hot last time. The fluid only needs to reach 100degrees for that to happen.

If it passed a WOF like that, maybe your being paranoid?? The difference between the work ute and the Pajero maybe??

Yea cheers, when I just changed master cylinder I redid all the fluid today, started at the rear until the aerated fluid stopped coming out and moved to the front. I'm not just being paranoid as the pedal never used to take a couple of pumps to work

I only tell my passengers when I get home that they need a double pump to work properly. I'll give them a good going over tomorrow for more air....

[Overkill]

Yea cheers, when I just changed master cylinder I redid all the fluid today, started at the rear until the aerated fluid stopped coming out and moved to the front. I'm not just being paranoid as the pedal never used to take a couple of pumps to work

I only tell my passengers when I get home that they need a double pump to work properly. I'll give them a good going over tomorrow for more air....

Are you using one of those "one man" jobby brake bleed kits? Can't really beat a two man operation to really force out the fluid and air.....

[Cameron]

when you're starting at the back, you're doing all three points back there huh? the one on the proportioning valve is imperative to bleed.

I gave my paj (same as yours) a flush when I bought it chasing another problem, and neglected to do the proportioning valve bleeder. pedal was flacid as shit without giving it a couple of kicks.

bleed it there, then a quick double check by bleeding rear calipers again and you'll be cookin'
be weary that it's a bit of a bugger to get to so jack it up as far as you can off the floor. no idea if it helps but i also unhooked mine and set it to simulate a heavy load when bleeding both it and the rear calipers.

one man bleeder and also vaccuum bleeder were both rather shit for the job too. I got the missus to do the old "pump pump pump hold *SPLOODGE*" deal.
she also helped me bleed the brakes on the paj'

[SP450andLE]

There could be a minute split in the brakelines somewhere, just letting enough air in to reduce braking...

[tweake]

I thought about that but then thought if it was swelling then surely with the pressure these come under it would have just gone pop!

they bulge really well without popping !
had one on my old work van. tho double tap on the brakes was normal due to rear drum brakes.

i don't know the 4x4, but if its got a prop valve make sure its done in the right order.

[NJV6]

Are you using one of those "one man" jobby brake bleed kits? Can't really beat a two man operation to really force out the fluid and air.....

Na, two of us are doing the bleed job.

I gave my paj (same as yours) a flush when I bought it chasing another problem, and neglected to do the proportioning valve bleeder. pedal was flacid as shit without giving it a couple of kicks.

"pump pump pump hold *SPLOODGE*"

Mine doesn't have a proportioning valve. both SWB's I've had haven't but the LWB's do...

There could be a minute split in the brakelines somewhere, just letting enough air in to reduce braking...

Yea but surely to surelyness it would also be letting fluid OUT when hard on the pedal and it ain't that.

Went for a skid tonight, it will lock the rears now before the front Front wouldn't even dive under braking unless I pumped them a few times before the big slam. Big bleed job coming tomorrow!!

[Cameron]

weird! mine's an swb and definitely has a proportioning valve.
good luck tomorrow.

[NJV6]

Maybe it is just the ABS ones. Neither of mine had ABS.

[Cameron]

perhaps. Mine's ABS so I guess that may be the difference! keen to rid myself of that burdon at some stage too.....
mine seems to have an electronic speedo too which aparently isn't run of the mill either. doesn't help when I need a new sender for it!

[NJV6]

Na electronic speedo's are the norm, they changed sometime in1991-1992. Parts for it should be easy!

[Lynx]

Maybe try bleeding the master cylinder, stranger things have happened.

Cheers Daniel