after fixing the diff and busted axle in the 1000 coupe i went to bleed the brakes. i opened both the bleeder nipples at the rear of the car and got my mate to pump the pedal. nothing came out... and the pedal was still rock hard after a period of softness.

so i had a look in the resevoir and it was ful! ok... i then thought i'd open the bleeder nipple on the master cylinder. no fluid coming out there either, but some air was. and it was still full of fluid!

right, took the filter out of the resi and then took the resevoir totally off, and put a "teaspoon" of fluid in the space that remained. still wouldn't flow though AND the brake for the front were fine, as if they were isolated.

so i thought i'd test it by going for a drive with zero fluid in the resevoir for the rear brakes. the front wheels would still lock up.

can a master cylinder isolate front to rear like that??? where would something be jammed???

the m/c is a tandem one, replacing the original. origins unknown.

worrying signs were the fluid was red... i'm hoping this wasn't transmission fluid


oh yeah, i've got some shots of the car i'll put up later tonight

Datsun 1000 coupes came with a tandem master cylinder as standard. All other B10 models,.... no, but coupes,... yes, so it might actually be the original.
Looks like you had better pull it off & post a picture of it for identification.
Once it's off, you may as well put a kit in it.

It's not the usual practice to bleed the brakes by opening more than one bleeder nipple at a time as it's a pain moving between wheels to close both nipples off before the pedal is raised in readiness for the next downstroke.
Make sure that the pushrod to the m/cylinder can move with a few thou of looseness when the pedal is full up to ensure that the piston is fully back.

Generally, bleed the wheel cylinder closest to the m/cylinder first, then move to the next one. Go back to the first one again,... just to be sure, but do only one at a time.

what i'm trying to say tho is no fluid is going through the resevoir at all. so if i undid both or only one of the bleeder nipples and went for a drive the brakes would be exactly the same, no fluid would leak and the front brakes would still work exactly the same.

i can't bleed the brakes at all coz the fluid is not moving, feels like the bleeders are still done up

Quote:Which is why i suggested pulling it off, & pulling it down. It's the front piston that services the rear brakes, & if the piston is siezed, or just stuck at the end of the bore, you will get the symptoms that you describe.
It's much easier to remove a stuck piston if the cylinder is on the bench. Once it's out you can make everything all nice & clean. A few new rubbers converts an unknown cylinder into a fresh part in a known condition. That should give peace of mind for only a few dollars outlay.

What happens when you take one of the bleed nipples on the master completely out?

I wouldnt bother wasting $20 on new rubbers for a 30 year old master because 30 year old rust will simply rip the #### out of them.

i didn't get the chance to pull it out completely, but when it was undone a few turns i could feel a little air if i put my finger over it. i think i'll pull apart another on i've got lying around to do some research. the thing is that the 1000 lives at my holiday house an hour and a half away

I had something like this happen on my b310, I was using a bleeder bottle and doing one side at a time, and it seemed the only fluid coming out was from my making suction with the bottle, I think what happens is that the long brake lines drain out and it takes many many pumps to get fluid back to them, and the proportioning valve may make it take longer. the easiest way might be to use a suction bleeder and pull the fluid to the back wheels.