Marina rear brake bleed problem...

[element]

Final job before the MOT & the open road; bleeding the brakes... The Marina master cylinder has two pipes leaving it, one goes forwards and splits in a two way union - going left & right to the respective front wheels, that was easy - some old fluid and now fresh and clear. The second pipe goes back to the rear, offside wheel. Here the pipe enters the back of the piston and another one leaves it and goes over the axle to the rear nearside wheel. At the latter there was the bleed nipple :



However, when I opened the bleed nipple here, & instructed 'down' to my wife in the car; nothing happened, no fluid, no air - as though the nipple valve wasn't functioning at all? It looks a bit corroded; does this happen to them - they corrode & seize up so not functioning anymore? Can I try to get a replacement nipple & just screw that in then bleed it?

Your wise words much appreciated

[andyf]

Re: Marina rear brake bleed problem...

When that happened to me it was the flexible hose from the body to the axle had collapsed

[b_caswell]

Re: Marina rear brake bleed problem...

That nipple looks like it may be an ABV type that has a non return valve in it, open the nipple even further and try again, as last resort remove completely. If still no joy I would suspect the flexible hose that connects to the axle, it may have collapsed internally.

Hi Andy, Great minds think alike!

[stevejgreen]

Re: Marina rear brake bleed problem...

Is there pressure in the slave cylinders on both sides of the car I.e can you see movement of the brake shoes.? If so then the chances are it's just a blocked bleed nipple as Ben suggests.
When was the brake fluid last changed? Could it be 30 years old from the Roadsters build date?

My favourite is to use a vacuum bleeder, making it a one man job, it also makes it far easier to flush all the fluid out of the system. The pressurised systems are IMHO much less controllable and have a habit of spraying brake fluid over nicely painted surfaces.

[element]

Re: Marina rear brake bleed problem...

The old fluid would be about 10yrs old, but the car sat still for 8yrs & has only ever done 575 miles... I'll open up the drums and watch the shoes when the brake pedal get pressed, it might be a blocked nipple. There are no compressible flexy hoses; this car only has copper tube brake lines with stainless sheathed flexy which doesn't look like it can be compressed.. Later in the week we'll have another look..

[andyf]

Re: Marina rear brake bleed problem...

They can still collapse inside as they are lined with rubber.

[stevejgreen]

Re: Marina rear brake bleed problem...

They can still collapse inside as they are lined with rubber.

Surely most stainless braided brake hoses are PTFE inside.

[David]

Re: Marina rear brake bleed problem...

Obvious I know, remove the nipple altogether and pump, that way you'll know if it's the nipple or a hose/pipe issue going to it.

At least yours is plumbed in correctly, mine appears to have been setup incorrectly when it was built in the 80's with the inlet going in the TOP of the assembly and the nipple on the bottom. Must have been fun to bleed air from that! All put right now.

[HairyDave]

Re: Marina rear brake bleed problem...

My S3 Land-Rover is like that, a nightmare to bleed, best bet is to re-plumb it to get the bleed nipple at the top.

[greyV8pete]

Re: Marina rear brake bleed problem...

Have a really good look at the rigid brake pipes to check that they haven't been flattened by a large stone or other vehicle component. I know of one classic car that was only braking on the fronts as the rear brake pipe had been squashed between the chassis and the rear axle. Made possible by incorrect fitment of the pipe run in the past.

[element]

Re: Marina rear brake bleed problem...

I haven't had a moment to look at it again yet but apparently the rear brake pipes are all copper tube there is no flexy at all, only the front has flexy stainless. The car hasn't been driven since Aug 2007 (apart from the other day when I took it round a 300m dirt road circuit outside the holding garage, brakes seem to work. As soon as I can I will check out the situation again. probably Thursday evening. Intermittently running on 3 cylinders so have just bought some nice new blue HT leads for some engine bling

[marlintom]

Re: Marina rear brake bleed problem...

Hmmm if it's all copper at the rear expect a ruptured or cracked line very soon, try checking again, there should be one flexible runing towards the rear axle and then going into copper that splits up to left and right

[cameronfurnival]

Re: Marina rear brake bleed problem...

brakes.JPG

Flexi should go between points 6 and 7. Have a good look
If you crack the joint where the pipe goes into the bottom of the cylinder, get a person to press down on the brake gently you should get fluid out, then crack the top joint - no fluid means stuck/ blocked cylinder. then just work through to the bleed nipple. It is possible there is a blockage.

[element]

Re: Marina rear brake bleed problem...

I finally had the time to get to the bottom of the problem... Took a rear drum off & the shoes didn't move when the pedal was pressed. Took the bleed screw completely out, nothing at all when pedal pressed. Undid the flexy (yes it did have a flexy exactly where you said it would be) bottom union & again nothing when pressed, undid the top of the flexy and then a good squirt of brake fluid came out. So the issue was as you've said - the flexy hose. Just ordered a new one. Brilliant help, many thanks..

[stevejgreen]

Re: Marina rear brake bleed problem...

Great, issue identified. I do wonder though just how much debris is left in the pipes only to be found later.
It's time for a mega flush with new fluid.