Brake fluid renewal and bleeding woes!

[orangebooboobearcrew]

Hi All,

Wondered if anyone can help re the above at all?

I changed the brake fluid on our 2.0ltr 1980 petrol air cooled today and bled afterwards but having just checked it the pedal is now really soft and has to be pumped to get brakes!

I drained the system completely (as per the Haynes) in order by opening each valve in the sequence listed, pumping the pedal until no more fluid came out, then tightened valve back up (one man kit used). I then refilled the system reservoir, then bled each wheel again in sequence until ran clear with no air / bubbles - topping up in between so never below half way.

All wheels clear of air and clutch done at same time. Clutch seems to work fine btw.

I am worried I might have damaged the seals in the master cylinder when pumping through (having now read posts on here). Would I defo be seeing leak on cab floor if so?

Supposed to be goin on hol Fri and worried I got no brakes now!

Thanks

[bigherb]

You don't drain the system when changing the fluid. Suck out the fluid from the reservoir (I use an old turkey baster) fill with fresh fluid. Then pump out 500ml form each rear wheel cylinder and 500ml from each lower calliper nipple (If fitted otherwise just 600ml from the top nipple) then 100ml from the upper nipples keep topping up the reservoir as necessary.
It sounds like you still have air in the system if the brakes pump up. It may be in the rear brake pressure regulator the early type had a bleed nipple for this purpose but will be almost certainly seized. Try getting someone to pump the pedal about 7 times and then hold the pedal down, open the bleed nipple until the pedal goes to the floor tighten the nipple and repeat until no more air comes through or better still invest in a pressure bleeder.

[Ian Hulley]

It sounds like you still have air in the system if the brakes pump up.

Agreed.

Ian

[jamesc76]

why the hell Haynes keeps giving out that utter w@nk system of changing fluid I dont know!!! All you need to do is empty the res ( as said above) then keep bleeding and topping up till clean fluid comes through!

You need some one else to pump it for you whilst your underneath as you will not see if all the air is out properly!

[orangebooboobearcrew]

Thanks guys.

Yes, it was my guess there is still air in the system somewhere but was at a loss as to where / why as one way bleed kit seemed to show no bubbles and clean fluid coming through.

I will try what you guys have suggested when I am back home Weds night and let you know if this works. Thank you all very much for your help with this.

Yeah, Haynes is rubbish - just a bare minimum covered in there really and no help when things go wrong!

Thanks again,

Chris

[orangebooboobearcrew]

Sorry, further silly questions - do I still need to do one wheel at a time presumably after pumping pedal 7 times then holiding down?

Do I need to do clutch as well as this already seems to be working?

Thanks

[bigherb]

Sorry, further silly questions - do I still need to do one wheel at a time presumably after pumping pedal 7 times then holiding down?
Thanks

Yes.

If the clutch is OK no need to bleed that again.

[California Dreamin]

That advice beggers belief......air is compressible and so will struggle to draw the fluid back through the system, letting the system run dry is not just bad practice, it is probably the worst thing you could do in the circumstances.

I always pressure bleed mine...which is the safest and best way as this doesn't involve pumping the pedal. Most garages use this method.

Martin

[orangebooboobearcrew]

Update...

Much better now - did the 7 pumps, then open nipple, then close, on each wheel and pedal is much firmer now

Went for a test drive and feels much better; nowhere near as spongy.

Wasn't actually that difficult once you know what you are doing (thanks guys) and have the courage of your convictions to keep flushing until you have no air bubbles.

Thanks again. We can go on our holidays now