Cant get pressure in the brakes :(

[alexanderfitu]

Hi all





I have recently changed out all the lines in my 1991 XJ600. I have replaced them all with goodridge lines.


I have also overhauled the master cylinder. (new mc kit)


The problem I have, is that I cant get the brakes to pump up, I have clear fluid showing at the bleed nipples on the front fork, but no pressure in the lever.


Any thoughts?

[red98]

what bleeding method are you using ?

[richfzs]

Not a very good one

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[Dead Eye]

If you aren't getting pressure then there must be a leak somewhere in the system. Is brake fluid leaking from anywhere obvious? Make sure the reservoir never gets too low otherwise you will draw air in...

I know I am stating the obvious, but its the best place to start :p

[alexanderfitu]

what bleeding method are you using ?

Pump lever 2-3 times, pull lever all the way, open bleed nipple, close bleep nipple, release lever, rinse repeat.

[alexanderfitu]

If you aren't getting pressure then there must be a leak somewhere in the system. Is brake fluid leaking from anywhere obvious? Make sure the reservoir never gets too low otherwise you will draw air in...

I know I am stating the obvious, but its the best place to start :p

Defo no leaks! I have gone over every joint, cant see any leaking fluid, nor any from the calipers.

[richfzs]

And you're certain the fluid isn't dropping too low in the reservoir at any time?

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[alexanderfitu]

100 percent.  I'm keeping it topped up.  Pulling on the lever does move the calipers a tiny bit.  Making me think there is still lots of air in the system.

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[richfzs]

Try the "clamp the brakes on" and leave overnight trick. Use a bungy our something to hold the lever back. The pressure (such as it is) encourages any air to bubble up and aid bleeding.

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[alexanderfitu]

Will give that a go with the calipers ip on the mudguard it should help.  Thanks 

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[richfzs]

Might be a silly question, but if you've got the calipers up on the mudguard, are the bleed nappies still at the top of the calipers (or at least the bit of the caliper that has fluid in it?

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[Razgruff]

Did you check the barrel of the master cylinder, was the overhaul kit in date?
Rubber is a perishable part and these kits have expiry dates.
Sounds like the fluid is passing back behind the plunger somehow, if you are sure you have no leaks or airlocks.
Rubber Brake parts shrink when dry, I suggest dismantling the Master Cylinder again and soak the Master Cylinder rubber parts in Brake fluid and checking them to ensure that they are the correct parts.
Also check that you re assembled it correctly

[richfzs]

Might be a silly question, but if you've got the calipers up on the mudguard, are the bleed nappies still at the top of the calipers (or at least the bit of the caliper that has fluid in it?

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fecking autocorrect 

[alexanderfitu]

yes yes and yes

All soaked in brake fluid whilst I was dismantling the old MC, I also laid out the parts in order that I removed them.

I pulled the hole thing apart again as I missed the washer initlaly and checked the bore at the same time, all clear.

Anyway, I have sorte it now there were air pockets in the caliper bodies, pushing the pistons in further and then pumping them out again sorted it Nice firm lever now, thanks all!

[Chris]

*insert "hard" innuendo here*
 
Glad you got it sorted mate! 
 
Chris

[alexanderfitu]

Haha! I resisted in the post

[BBROWN1664]

I had that problem when I put braded hoses on a bike a few years ago. No matter how much lever pumping or clamping back of the lever, nothing would shift the air. the answer was to rasie the capliper above the master cylinder and bleed it then refit it.