Spongy brakes after fluid flush

A

ajguk

Member
Hi
I recently replaced my brakes all round on my 2009 30i. I decided whilst it was up on axel stands I should replace the brake fluid as I'm pretty sure it hasn't been done for some years. I used a Gunson Eezibleed kit and bled all 4 corners - both front nipples were blocked so I removed them and cleared the holes, and reassembled before carrying on. The brakes immediately felt spongy, so I assumed I had introduced some air into the system, perhaps with a bad seal on the bleed kit.

Today I've started again and did all four, in the following order: o/s rear, n/s rear, o/s front, n/s front (I seem to be getting conflicting opinions on which way to perform the procedure). Unfortunately the brake pedal is now sinking under pressure when the engine is on....they were fine before I replaced everything, I'm now wondering if I've just managed to get some air in again (likely) or whether my master cylinder is done for.

Anyone here faced a similar issue on the Z or another car perhaps? Would it be best now to do each one individually and test after each caliper is bled? At the moment I'm a bit stuck as I don't fancy even driving it to the garage!

Thanks
 
I wonder if I need to push the pressure up a bit - it's not recommended to go above 20psi with the kit I've got. Reassuring at least to know what the most likely problem is, thanks
 
ajguk said:
I wonder if I need to push the pressure up a bit - it's not recommended to go above 20psi with the kit I've got. Reassuring at least to know what the most likely problem is, thanks
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If your kit says no more than 20psi then it’s perhaps the kit that’s….errrrr…not the best.

I have the same kit as Rockhopper and keep it pumped to 40psi minimum, it’s been down to 20psi as an experiment and the fluid rate was feeble.
 
You can also run the abs pump on all four corners after an initial bleed. Then bleed each corner in turn. When using ISTA it instructs five full depressions of the pedal before closing the valve. Takes two people. I had similar with mine recently until I did it properly. Now it’s spot on again.
 
You shouldn’t need to run the ABS pump if you haven’t let all the fluid out. A simple fluid change should be easy.
 
Rockhopper said:
You shouldn’t need to run the ABS pump if you haven’t let all the fluid out. A simple fluid change should be easy.
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It is good practice when doing a full fluid change otherwise old fluid remains. He did say he did a fluid flush.
 
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It really isn’t. If you don’t get air in then just flushing new fluid through is all you need to do. You only need to cycle the ABS pump if you’ve got air in there.
 
Maybe he did get some air in there..the only other option is incorrectly mounted / re assembled brakes..
 
OK have bought a similar tool to the one you have Rockhopper. Does the order of the bleed matter hugely? As in, I would obviously do the rears first, is it that important which side I hit first? The reservoir is on the driver's side, so my initial assumption was passenger side rear first but ChatGPT insisted otherwise. I used that as I couldn't seem to find a concrete answer elsewhere. So far I've done both ordering types (n/s/r, o/s/r, n/s/f, o/s/f AND o/s/r, n/s/r, o/s/f, n/s/f).
 
ajguk said:
OK have bought a similar tool to the one you have Rockhopper. Does the order of the bleed matter hugely? As in, I would obviously do the rears first, is it that important which side I hit first? The reservoir is on the driver's side, so my initial assumption was passenger side rear first but ChatGPT insisted otherwise. I used that as I couldn't seem to find a concrete answer elsewhere. So far I've done both ordering types (n/s/r, o/s/r, n/s/f, o/s/f AND o/s/r, n/s/r, o/s/f, n/s/f).
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Normal logic is furthest lines from master cylinder first FWIW I was shocked at how much fluid I had to pump through to fully purge the lines ..well over a litre!
 
B21 said:
Normal logic is furthest lines from master cylinder first FWIW I was shocked at how much fluid I had to pump through to fully purge the lines ..well over a litre!
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That's the other part I'm struggling with :) If we are talking diagonally for the furthest, I would assume passenger side rear first?
 
ajguk said:
That's the other part I'm struggling with :) If we are talking diagonally for the furthest, I would assume passenger side rear first?
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All lines run back to the dsc so personally I can't see it making a big difference apart from the fact that the longer lines have more air..I found a pressure bleeder and two people and ISTA and 2 litres of fluid cracked it in the end
 
Rockhopper said:
It really isn’t. If you don’t get air in then just flushing new fluid through is all you need to do. You only need to cycle the ABS pump if you’ve got air in there.
Click to expand...
I’m only quoting what it says in the procedure on ISTA.
 
Rockhopper said:
It really isn’t. If you don’t get air in then just flushing new fluid through is all you need to do. You only need to cycle the ABS pump if you’ve got air in there.
Click to expand...
I didn’t think I had that much air in my system as I kept brake pressure on my pedal until everything was installed. However it took two proper flushes to eradicate all air. You will only know if air is in by doing it properly in my experience.

But if it can be done easier fair enough. If that doesn’t work then it may need doing properly.
 
ajguk said:
Hi
I recently replaced my brakes all round on my 2009 30i. I decided whilst it was up on axel stands I should replace the brake fluid as I'm pretty sure it hasn't been done for some years. I used a Gunson Eezibleed kit and bled all 4 corners - both front nipples were blocked so I removed them and cleared the holes, and reassembled before carrying on. The brakes immediately felt spongy, so I assumed I had introduced some air into the system, perhaps with a bad seal on the bleed kit.

Today I've started again and did all four, in the following order: o/s rear, n/s rear, o/s front, n/s front (I seem to be getting conflicting opinions on which way to perform the procedure). Unfortunately the brake pedal is now sinking under pressure when the engine is on....they were fine before I replaced everything, I'm now wondering if I've just managed to get some air in again (likely) or whether my master cylinder is done for.

Anyone here faced a similar issue on the Z or another car perhaps? Would it be best now to do each one individually and test after each caliper is bled? At the moment I'm a bit stuck as I don't fancy even driving it to the garage!

Thanks
Click to expand...

Okay , so lets be honest..everything was fine before you ' tried to fix it' .

Just take it to 'Kwikfit' and get them to do a 'Brake fluid Flush' ~ £50... DO NOT MENTION THAT YOU tried and *UCKED IT UP ! ...Make sure that that your brake flush warning light is showing past due. ( you can easily do this in the car service menu options) . Let them do the flush and if there are any problems ....you can blame Kwik fit .
 
Viper4 said:
Okay , so lets be honest..everything was fine before you ' tried to fix it' .

Just take it to 'Kwikfit' and get them to do a 'Brake fluid Flush' ~ £50... DO NOT MENTION THAT YOU tried and *UCKED IT UP ! ...Make sure that that your brake flush warning light is showing past due. ( you can easily do this in the car service menu options) . Let them do the flush and if there are any problems ....you can blame Kwik fit .
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I would not trust KF to blow a balloon up. Plus we never learn how to do it ourselves. There is something good about overcoming a problem yourself. Just keep trying and the air will come out. Might take a few goes, but it will!
 
Reamesy said:
I would not trust KF to blow a balloon up. Plus we never learn how to do it ourselves. There is something good about overcoming a problem yourself. Just keep trying and the air will come out. Might take a few goes, but it will!
Click to expand...
Agreed. Will give it another go and report back. Last place I would be going is Kwik Fit but I appreciate the snark :|
 
If bleeding one man job, i used old damper to apply pressure to the pedal braced against the seat frame.
Then open whichever nipple and close, the damper pushes down the pedal.
Still run abs purge though using the obd reader.
Then you can monitor the bubbles bleeding out yourself.
 
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