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Bleeding Brakes Problem

David Kemps

By David Kemps,
in General Maintenance

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David Kemps Enthusiast

David Kemps

Posted
Posted

Changed brake pads, tried to bleed brakes using the sequence specified in the manual, back left, back right, front left, front right, pedal goes down to the floor when pushed, seems like heaps of air in the system still.

Repeated 3 times, in different sequences, pedal is getting better but not safe enough to drive.

QUESTIONS

Any tips for non-abs gts25t r33?

Do you bleed the nipple on the master cylinder? (non-abs)

Anyone else have any problems?

This is really annoying me, gonna buy some cheaper fluid tomorrow to try again just to get it going cause i just wasted 1 litre of my good stuff.

PS: I've bleed brakes in cars heaps of times, no problems, but not this car before so really don't think its my technique.

Don't wanna spend the money taking it to a shop, especially for a easy thing like this.

Dave

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Abo Bob Grand Master

Abo Bob

Posted
Posted

I would do it again but tighten the nipple before the helper gets their foot to the floor. Ie while the fluid is still coming out fast.

Takes longer but at least you know no air is going back in from the nipple. Where else could it get in?

predator Grand Master

predator

Posted
Posted

Exact same problem when I was trying on another car over the weekend. Bled until no air was coming out, tightened whilst pressure 3/4 of the way off the pedal. Still same problem. Exact same method I've done on my car after changing the brake system (new calipers, discs) and no such problem.

No idea.. he has just done an engine conversion and brake conversion so maybe thinking either incorrect master cylinder, or some sort of problem with the brake booster? Is there any electronic feedback from the ECU during braking that could be the problem?

There doesn't appear to be any fluid on the ground, any leak of any kind, etc.

blind_elk Grand Master

blind_elk

Posted
Posted

So, a new master cylinder was fitted to the booster? Or a new booster fitted to the master?

I had a similar experience years ago, fitting a 260Z master into a 240Z. Turned out a small spacer fell off inside the booster. Everything felt fine bleeding, but went out the door when the engine was started and you got some vacuum assist on the system.

David Kemps Enthusiast

David Kemps

Posted
  • Author
Posted

ok, bled again with new fluid and bleeder kit, much easier and better

DEFINATELY no air in the lines now, but still pedal feels like crap, goes down heaps before working, at least it does work now i guess.

drove the car, is driveable and does stop fine just not that great yet, can reach the floor.

Any other ideas anyone?

Duncan Grand Master

Duncan

Posted
Posted

yeah check out the master cylinder if you are sure it has been bled OK.

Hold your foot down on the brake....does it sink slowly to the floor? thats how to tell you have a master cylinder problem

gts4diehard Rising Star

gts4diehard

Posted
Posted

sometimes when you push all the fluid out through the wheel bleed points you push all the crap thats been sitting in your brake resoivoir down and damage the seals of the master cylinder unit. If the resoivoir is dirty i have in the past syphoned it out of the resoivoir to reduce the chance of dirt going down, you will use more fluid bleeding it as there is a good chande you will introduce air into the system but it can save hassles.

Jax Collaborator

Jax

Posted
Posted

Sounds like you still have air in system. Some vehicles, always, have been harder to bleed than others, and really need "pressure bleeding". With that you pass a greater volume of fluid thru, in less time, which can move a pocket of air, which just ocillates back and forward with the amount of fluid displaced by just a pedal stroke.

Imagine a loop of brakeline, with a little pocket of air in top of loop, unless you can displace enough fluid,you will just force the air bubble downwards,but not far enough to get it out thru the nipple. Stop bleeding and it goes bach to top of loop.

Sometimes, if you can identify such high spots, you can jack up that side [or end] of car and succeed with bleeding.

Jax Collaborator

Jax

Posted
Posted

Depends on the size of any loop, and therefore the size of bubble. Very little fluid is displaced to apply brakes. Pads run virtually touching discs. All you have to do is compress the air in line. Believe me, it is not a new problem. One model of 'Falcon' late 60s or early70s was virtually impossible , and there's been plenty of others, through this one cause.

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