copper pipe in to new master cylinder weeping, quick one ...

[markbigears]

Hi guys, Hopfully someone will answer his before tonight as I'm planing to bleed the systwm ....fitted the new master clutch cylinder yesterday, all went well, still got air in the system, but ran out of time last night.
After a few hours I noticed a slight weep around the pipe that goes from the master cylinder out to the slave (the long brass nut).
Couple of questions.... i've noticed the nut has about 1mm gap bewteen the bottom of the nut and the base of the cylinder. I can't remeber if it sat flush? I've tightened it right up
so no more to screw down? I also didn't use any grease on the thread, should I have? As I'm going to drain the fluid again, taking the screw out again to put right isn't an issue.
Thanks guys, Mark

[shoab]

Dont put grease on the thread it may contaminate the brake fluid...just use some brake fluid.

A tube nut never goes right flush to the cylinder, there is always a thread or two showing as the seal is between the flare on the end of the pipe and the inside of the cylinder. If you have tightened up the nut then you need to take it out and have a look at the flare to make sure that it is not split and is the correct type of flare either male or female ie convex or concave on the pipe end.

Graham

[markbigears]

Cheers Graham, I thought as much about not using grease, will take it out again and have a look. All i've done is remove old cylinder and put new one on? Screwed in fine too, so don't think ive cross threaded it, but good to know there is always a gap. Mark

[Barkychoc]

If it's not sealing you just cut the end off the pipe and make it off again, a hand held flaring tool is only 10 to 20 quid. I prefer to use a rotating type cutter as with a hacksaw you get metal filings inside the pipe. You can get a couple more inches of pipe if you reshape them carefully. Reuse the old nut if the thread is ok.

[markbigears]

Thanks Chris. Drained the system tonight, unscrewed it, cleaned the end up and refitted, no leak! On the negative side the clutch pedal is still hard and won't go down, so it wasn't the master cylinder. Slave cylinder is next on my list. Any ideas fault finding wise? Pedal goes to the floor when bleed nipple on the slave open, but hard as soon as I tighten up.

Edited by markbigears on Monday 28th May 23:36

[GreenV8S]

Either the slave has seized, or the pivot has collapsed, or the release mechanism has jammed somehow. I'd probably put my 10p bet on it being a collapsed pivot, but you'll find out as soon as you unbolt the slave.

[phillpot]

GreenV8S said:

I'd probably put my 10p bet on it being a collapsed pivot.

Possibly not on a V6 which is push - bearing - pivot, whereas V8 is push - pivot - bearing (i think)

Could be push rod between slave and release arm fell out or "punched" through arm or, as suggested, slave is siezed solid?

[markbigears]

Many thanks guys, will order slave today, appreciate all your input ... Again !