2007 D40 Navara brake issue

[Rocky198688]

Hey guys my navara has a sinking brake pedal. I changed the master cylinder which i bench bled first. I then bled it from the LSV and worked my way to the front ( I used a pressure bleeder). With the engine off my brake pedal is rock solid. As soon as i start it the brake pedal sinks all the way to the floor. Ive bleed it 4 times now and no change. My rear shoes are adjusted a few clicks off. The master cylinder was a aftermarket one from BNT. Anyone had issues with the ABS module causing this? If there is air in that should that bleed up with the key on or do you need a scan tool to oprate the valves?

 

[Old.Tony]

Check all the vacuum hoses. Look for any sign of hardening. There's a hose that comes across the top of the engine to a widget on a pipe at the front of the engine bay's left hand side and from there to the turbocharger. Any of these hoses could cause the problem as vacuum is lost.

The hose is just 3mm ID vac hose, I bought some from Supercheap for $5 per metre. You'll need 3 metres to replace all of it in the engine bay.

 

[Rocky198688]

Check all the vacuum hoses. Look for any sign of hardening. There's a hose that comes across the top of the engine to a widget on a pipe at the front of the engine bay's left hand side and from there to the turbocharger. Any of these hoses could cause the problem as vacuum is lost.

The hose is just 3mm ID vac hose, I bought some from Supercheap for $5 per metre. You'll need 3 metres to replace all of it in the engine bay.

Will loss of vaccum cause my spongy pedal while its running? Cheers

 

[Old.Tony]

That's why I mention it. The vacuum system is connected to the brake booster because that's what the booster uses to amplify the brake power.

 

[Rocky198688]

Awesome mate will have a look and report my results. Thanks

 

[[email protected]]

vaccuum leaks plus one of many causes,

Have a full brake pedal when engine is off but goes to floor when running?


If the brake pedal goes to the floor but still stops, you could be having a failed brake power booster. The power booster's role in the braking process is giving power assistance when the driver depresses the pedal. This means that you don't have to make a very high amount of power to stop the car.

 

[Horatius]

Will loss of vaccum cause my spongy pedal while its running? Cheers

A pedal that sinks "all the way to the floor" indicates a little more than just being "spongy" by my definition lol.

If you take the vacuum line off the booster (might need to block it or kink it over) what difference does it make?

I would have thought a (lack of) vacuum problem itself would be more likely to result in a higher pedal that is difficult to push?

It could be an internal problem in the booster itself though, perhaps a valve is not sealing and pressure difference is venting or pushing air into the master cylinder?

 

[Horatius]

Anyone had issues with the ABS module causing this? If there is air in that should that bleed up with the key on or do you need a scan tool to oprate the valves?

No idea sorry. Hopefully someone familiar with abs or your model will be along. It does sound like air in the lines.

 

[Been a while]

Don't know abs but navs can be a pain for this.. I've done it all but the best way I found was vacume bleed... crank the compressor up too!

I've done them with pressure too but, to get the pressure to move the air bubbles in the lines you'd better have a nice new resivour to take the pressure! Pressure is more for fluid changes, sometimes it will work, then others, well here we are..

The air moves easier and quicker by vacume with the Navaras! Theyre a shite of a line to bleed, they're like a roller coaster track! Up down, round in circles!

Are you bleeding the master cylinder then prop valve then left rear, right rear, left front finishing on right front? Don't forget the prop valve

 

[Been a while]

No idea sorry. Hopefully someone familiar with abs or your model will be along. It does sound like air in the lines.

Lol yup, its air, usually a stinking bubble in the master and because he's pressure bleeding the fluid rolls over the bubble! I shite you not my man! The peddle thing is a trip too, I always get that... I've even ran the motor and bleed them lol all because one was busting my b$#%, nearly 4 lt on that one.. That got it though, but I'm not sure about firing ones with ABS eh

 

[Horatius]

^ Mine (D22) is simple to bleed with a cheapy ebay vacuum bleeder. I change the brake and clutch fluid occasionally, never had the slightest problem. Just lucky perhaps.

Though I agree, sounds there's still lots of air in the op brakes.

 

[Been a while]

Manually, by peddle, prime/bleed that master again, use bleed screw then crack lines from master and manual prime/bleed and close line- then pressure bleed lines to slaves.. bleed prop, then wheels. all the best bloke..

 

[Been a while]

^ Mine (D22) is simple to bleed with a cheapy ebay vacuum bleeder. I change the brake and clutch fluid occasionally, never had the slightest problem. Just lucky perhaps.

Though I agree, sounds there's still lots of air in the op brakes.

Yup navs, they're a temperamental swine sometimes stinking knuckle busters!

Ahhh you vacume bleed too! Took me "many a go" to work that one out! Weird huh they hate peddle bleeding too! even from the d21 days I never had luck with it..

Wonder what the manual states!

 

[Horatius]

Not sure with D40. The D22 manual refers to bleeding via pedal in following order... lsv > rear left > rear right > front left > front right > abs actuator (if applicable). It also mentions to disconnect/unplug abs actuator before doing this. Whether that's applicable to this model, no idea.

 

[Rocky198688]

Cheers guys for all the info. Thats really interesting about the pressure bleeder rolling over past the airlock. Will put the vacuum bleeder on it tonight starting at the lsv. Will report my findings. Sounds like the general consensus is these are just a absolute mongrel to bleed haha

 

[Been a while]

Cheers guys for all the info. Thats really interesting about the pressure bleeder rolling over past the airlock. Will put the vacuum bleeder on it tonight starting at the lsv. Will report my findings. Sounds like the general consensus is these are just a absolute mongrel to bleed haha

Yup, or under the bubble.. surface tension or something, all I know it can drive you nuts.. But that's it bloke!
Oh and the ABS that was mentioned, I do remember something about them being different, never touched one.. But I bet he's right, that and Mr and Mrs Bubble are driving you nuts..

 

[Been a while]

No, start at master! Make sure she's primed! Then prop valve, then L.Rear etc

 

[Been a while]

Not sure with D40. The D22 manual refers to bleeding via pedal in following order... lsv > rear left > rear right > front left > front right > abs actuator (if applicable). It also mentions to disconnect/unplug abs actuator before doing this. Whether that's applicable to this model, no idea.

Well there you go, I have never successfully peddle bleed one lol why, no stinking idea...
But I'd be reading up on the ABS for sure.

 

[Rocky198688]

Hey guys at a complete loss here. My pedal still goes to the floor but if i stomp the brakes driving i can set the abs off on tar seal in the dry. If anyone has any info on weather i maybe need to operate the abs valves will bleeding or something would be much appreciated. Cheers

 

[ericcs]

my d40 has had a sinking pedal when running all it's life(300k), hard as a rock when not. Have just accepted it as the norm!