Front Brakes - No Fluid Coming Out During Bleeding?

[nicknikolovski]

Hi, new to this forum.

I have a NC30 VFR400R. I was changing my brake fluid in the front & rear reservoirs.

Changed the brake fluid in the rear reservoir easily and quickly so no problem there.

My problem is with the front brake bleeding. The level was at upper mark, so I took off the reservoir cap, connected a clear hose and bottle to the left front caliper bleed screw and then tried the RHF bleed screw. I proceeded by moving the lever in, out, in, out about 3-4 times. I then held in the lever and cracked open the bleed screw. Hardly any fluid came out. Compared to the rear brake system, the fluid was just dribbling out. Now after trying to bleed the brakes (both LHF & RHF bleed screws), I have no pressure/fluid flow to the calipers which means I have no brakes.

I then thought the bleed screws were blocked/clogged with dirt or rust. I took them off the calipers, blew them out with compressed air and refitted them. Even after this there is hardly any fluid coming out. I also removed and blew out the front brake lines, again still no fluid flow.
I know it is not air causing this because you still get fluid coming out with air bubbles normally.

I am thinking the master cylinder has shit itself. Am I correct?

Thanks and any help is appreciated.

[MexicanGringo]

If some fluid comes down the lines but not enough to bleed all air out, it might be that fluid isn't entering the master cylinder properly, its supposed to be blocked by the piston when the piston travels forward, and then flow into cylinder when piston returns, on my rear brake fluid wasn't entering the cylinder because of some kind of block at the cylinder port. Otherwise the piston isn't pressurising because its worn, but if you had brakes before its not likely. Check the reservoir level drops when you work the lever, then you know fluids entering system

[robbiemturbo]

i had the same problem a while ago, no pressure at all, pulled master cylinder apart thinking a seal had gone, but it was fine. I finally sorted it by fitting a hose to the bleed nipple on each caliper in turn and sucking the fluid through (stop before you get a mouthfull!!). Still had no pressure, but then bled the master cylinder itself by loosening the banjo bolt and pulling lever, closing bolt, releasing lever, (same way you bleed at the nipple). With that done i did the same at the caliper banjo bolts, and finally at the nipples again. Sorted!!

[fixer]

Use a syringe to pull the fluid through it will work.I know i had the same problem and the knowledgeable people on this site helped with said solution.

[Cammo]

It's hard to get the air out of the master cylinder because it's the highest point in the lines (the air rises up there).

I do as robbieturbo said and crack open the banjo bolt on the m/c, just as you would the bleed nipples on the calipers. Just tie a rag around it so fluid doesn't run down the lines everywhere.

Bleed the m/c bolt a few times (you'll see when the air and bubbles stop coming out), then give the calipers a proper bleed.

[nicknikolovski]

Thanks guys, will try your ideas out and let you know.

I had another idea, what about using a vacuum operated brake bleeder to suck the fluid through the calipers? Will that work?

Or attach a pipe and oiling can full of brake fluid onto each of the bleeder valves and reverse bleed the system up back to the reservoir?

[hunter]

The vacuum bleeder will work.i used it on my bike.

[nicknikolovski]

Thanks again to all that helped out with their suggestions, problem is fixed - alot of air in the system. Used the vacuum bleeder and it worked a treat.