Bleeding Drama HELP

Fitted stainless braided hoses to my Targa and before doing so, the brakes worked just fine though the gunge that came out was alarming. I have renewed all the pads. The independent front works ok. The linked system just wont bleed. I have tried a vacuum pump to no effect. I have refurbed the master cylinder and still the system wont bleed. I have bled from the nipple on the back of the splitter, from the front brake and from the rear. If I pump the brake pedal, nothing happens. I have even tried evacuating air by cracking off the pipe union after the master in the way you would if you were bleeding the fuel system on a diesel. I now suspect that even though I have used a refurb kit on the master cylinder, it is nonetheless knackered. I don’t want to spend £120 on a new one unless I can be certain it is at fault. Can anyone suggest how I can definitively diagnose where the fault is? To date I have drawn two litres of fluid through!. Incidentally, the master does not use a circlip to retain the plunger but some sort of scraper ring which is a push fit. Very difficult to fit though I managed it in the end. Any help would be much appreciated as I am really struggling with this and have never had so much difficulty with what is a pretty simple maintenance exercise.

The only time this happened to me it was a bleed nipple not seated correctly and was an absolute nightmare to find.

I tend to put ptfe round every thread BUT ti ewas the bottom of a nipple I had bought new stainless ones and wrongly thought it could NOT possibly be them !!! swapped it back for an ond one and presto.

You can check the master cyl by disconnecting and closing off the end if it pressurises it should be OK

As you are aware brake systems HAVE to be exceedingly clean and the nipples have to drop right into place.
It is very difficult to figure out a problem by remote…

I would suggest going back to basics and taking the system off the bike to save any fluid leaks causing more mayhem then checking the master cyl is pressurising.

When I had to refurb the Yam master cyl I took it into Twiggers Mark charged me a fiver to fit the parts while I waited.

Got home put the front hose to caliper on the bench and filled and checked the pressure there before fitting it to the bike…

It seems a long process BUT saved more time.

You can thake the rear Mcyl pop a hose and front caliper onto it on the bench to get the cyl checked for pressure IF that is OK them it has to be the splitter IF the Targa has one or the caliper end buddy.

Yes, that’s helpful thanks though not sure I can fit a brake hose direct to the master cylinder though as it does have a splitter. I am starting to suspect a partially blocked splitter which is the only part of the system I haven’t had a go at and have read somewhere that there is a ball bearing thing in there that could be stuck? Yep, have been clinical in my cleanliness which I know is more critical than usual in the case of brakes and components. Will try cracking off each union beginning with the master cylinder and working up to the outlets of the splitter via the splitter input to see if I have pressure and where, this evening.

To fit that retaining ring in the master cylinder, you need a deep socket or similar which just fits inside the M/C bore. Then with the M/C resting on a solid bench, bottom down, push the ring down as far as you can then hit the socket a smart blow with a hammer to spread the retaining ring. Easy when you know, just done two for the V50. Now comes the bleeding fun. Did you get fluid out of the bleed nipples OK?

[QUOTE=Brian UK]

To fit that retaining ring in the master cylinder, you need a deep socket or similar which just fits inside the M/C bore. Then with the M/C resting on a solid bench, bottom down, push the ring down as far as you can then hit the socket a smart blow with a hammer to spread the retaining ring. Easy when you know, just done two for the V50. Now comes the bleeding fun. Did you get fluid out of the bleed nipples OK?[/QUOTE]

Yep sussed the socket trick no problem - even measured the depth to the ring prior to taking out the old one to make sure that when I drove the new one home, that it had fully seated. Fluid does come out of all the bleed nipples but, weirdly, one when left overnight and even then, only for the first few pumps then, nothing. That’s what I cant get my head round so must be a massive air lock somewhere or I think a partial blockage restricting flow which would explain the overnight thing. I think its time to take off the splitter and give that a blow through??

Can you release the feed pipe into the splitter and see if you can bleed to that point? You may need to close it when you allow the pedal to return of course.

weirdly, one when left overnight and even then,

That’s your problem the nipple is not seated properly buddy THAT is what I had took me days to figure it out, got a replacement nipple job done THAT is what I would do before getting anything else done …

don’t quite understand how a bleed nipple wouldn’t seat properly - can you explain what I should be looking for?

Yes, did that but not from the output sides of the splitter which I will try next which may show that the splitter is blocked. Here’s hoping . . .

Right the bleed nipple at the bottom is slightly V shaped and IF the bottom of the nipple does not seat correctly it allows air in OR fluid out IF fluid leaks under pressure once the pressure drops it allows air in…

pic here

It will work the brakes then overnight the pressure drops and next day NO brakes, sounds like that is yer problem, course I could be wrong it is alot more difficult by remote of course but !!!

Sometimes it is the nipple or the threads sometimes it is the base of the caliper it gets gunged up.

I use ptfe on the threads but to check take the nipple from the working front brake and replace…

Look closely at the bleed nipple and the shape and check it against the other nipples. new ones are not that expensive… check the base in the caliper, a pain but it sounds the most likely culprit.

Roy at did have stainless steel replacement brake nipples guzzibear2013-06-15 17:50:59

ok, got it and will check that. Managed to bleed the splitter and the rear calliper last night and was able to do so via the foot pedal at last. First though I pumped fluid through from the solid pipe to braided pipe connection of the linked front brake, up through the m/c and to the reservoir which I think blew through some air locks. After that I eventually got it so that I could pump through almost an entire reservoir of fluid through in 30 seconds so progress made. Just the front to do which is going to take longer because of the length of the pipework from splitter to calliper which must be a metre or so. If having done this it doesn’t hold its pressure, I will suspect and inspect the nipples but at least the m/c seems to be pumping now which it wasn’t before. Another trial by patience it seems.

It can help if you hold the calliper up higher than the pipework, allowing the air to go up.

tie the front calliper up as high as possible and then tie the brake pedal down to something heavy and leave for a day or so, any air will end up in the front caliper and after a guick re bleed you may be sorted

Excellent, will take the front calliper off and suspend it for a couple days before trying to bleed it. Thanks guys.

Back bleed it takes seconds…

Oh boy!

Just reading through the threads and have made a similar comment elsewhere - this is why I leave brakes to professionals!


I often find the pedal needs pumped up and down for a good long while after bleeding the system to get everything settled back in place. You could even drop a caliper off the disc and gently press the pedal to see if it is moving. EditJust a thought, Are you sure you have the seal on the master cylinder around the right way? From memory it is tapered and must face one direction, as explained in the leaflet you get with the kit.Don-Spada2013-06-16 23:24:26

The kit I bought came with the piston and seals already mounted, so incorrect assembly would be almost impossible.

I was sure until you asked! Fitted the kit, as Brian says, as it came out of the packet but yes I did check that the tapered rubber pointed in and that the expanding metal ring was to the outside as this is what gets whacked and spread with the long socket and when I looked at it, I couldn’t see that you would want to be whacking and spreading the exposed tapered rubber?

Guy both. elevates the caliper and ties down the lever/pedal when we encounter this sort of trouble…x