• Hi Guest!
    You can help ensure that British Car Forum (BCF) continues to provide a great place to engage in the British car hobby! If you find BCF a beneficial community, please consider supporting our efforts with a subscription.
    There are some perks with a member upgrade!
    **Upgrade Now**
    (PS: Subscribers don't see this gawd-aweful banner
Tips
Tips

Final fix for clutch pipe to master cylinder leak??

Share this page

warwick-steve

warwick-steve

Jedi Hopeful
Offline
Hi all
After fitting a new "can" type brake/clutch fluid reservoir I have lived with a small leak from the pipe from the reservoir where it is screwed into the master cylinder. I would have to top up about every 4 weeks. I decided to try and fix the problem. First I tried using some PTFE tape over the flared end of the pipe. The result was worse. (top up once per week!). Then I replaced the pipe with a spare that I had and the result was no better.

I now presume that the seat in the master cylinder is damaged in some way so I now intend to fit a new pipe and a new master cylinder. My questions are;

- is the replacement of the master cylinder straight forward?
- Anything to note? Any tips please?

One positive thing from this is that I have now got the hang of bleeding the clutch with long nose pliers a 3/8 spanner and an easybleed tube

Thanks in advance
Steve
 
If you're using a stainless pipe, the flare may have become work hardened and as a result, leaks. I had that happen after removing the stainless a couple of times. I've gradually replaced all my stainless pipes with cunifer.
 
Hi Steve
Thanks for getting back. The pipes are cunifer. I will try a brand new cunifer pipe again but if that is no better I will fit a new master cylinder and pipe. I just wondered if there is anything I should consider in this procedure as I have never done it before?
Steve
 
Bench bleed the MC before installing. Be careful to route the line so that nothing, like the flex cable for the cool air vent or an air filter, rubs against it.
 
warwick-steve said:
Hi Steve
Thanks for getting back. The pipes are cunifer. I will try a brand new cunifer pipe again but if that is no better I will fit a new master cylinder and pipe. I just wondered if there is anything I should consider in this procedure as I have never done it before?
Steve
Click to expand...

If you're making your own pipe, be sure to not squish the second flare too hard. It's supposed to compress slightly when you tighten the tube nut into the seat. With cunifer, you can also anneal the flare by heating with a torch or gas burner until it turns red, then allowing it to air-cool.

Addendum: annealing could possibly restore one of your old flares enough to seal.
 
Last edited:
I have always wondered how you bench bleed the clutch master cylinder and then get it installed in the tight area on the bulk head without spilling any of the fluid all over everything. It seemed impossible to do. Can someone please explain?
 
Rob Glasgow said:
I have always wondered how you bench bleed the clutch master cylinder and then get it installed in the tight area on the bulk head without spilling any of the fluid all over everything. It seemed impossible to do. Can someone please explain?
Click to expand...
silicone plugs in the ports until you get the tubes fitted.
 
Gentlemen
Thanks for the information.
I guess bench bleeding is to ensure all the air is out of the MC and replaced by fluid before connecting up and making the final bleeding process easier..
For this purpose I would do it on the car using the old/existing pipe from the reservoir to the new MC and use a spare pipe and connection at the outlet of the MC. Once the MC is bled I would fit the new MC and a new pipe from the reservoir.

I do regret now throwing the old reservoir away as it would have been useful for bench bleeding off the car.

Please excuse this possibly stupid question but is it possible that an already used and leaky copper/cunifer pipe flare end could damage the seat in the new MC. I presume that as the pipe is softer than the mc alloy casting this cannot happen??


On fitting the new MC are there mechanical adjustments to be made at the pedal linkage?

Thanks again.
Steve
 
Do not be sceptical of using a bright light and a good magnifying glass to inspect the seat in the port. If there is any scoring, dents, or galling ( which is when displaced metal is "smeared" or balled up) you should be able to see it. If it looks good it probably is fine. If you can use a macro function on a digital camera and view a photo on a good computer screen it is sometimes even better than direct view; if your resolution is high you can blow it way up on the screen.
 
warwick-steve said:
Gentlemen...

Please excuse this possibly stupid question but is it possible that an already used and leaky copper/cunifer pipe flare end could damage the seat in the new MC. I presume that as the pipe is softer than the mc alloy casting this cannot happen??


On fitting the new MC are there mechanical adjustments to be made at the pedal linkage?

Thanks again.
Steve
Click to expand...

I don't think a cunifer pipe flare would damage the seat in a steel (iron?) MC, but when mating a pipe to a seat the final 'forming,' if you will, is done when you tighten the fitting. That is, the flare of the pipe would have been formed somewhat to the seat of the previous cyl. This may be more of an issue with steel lines, as cunifer is softer, but there is a chance you would get a leak.

Just check the play on the pedal when you're done and adjust if necessary. While you're under the fascia twisted like a pretzel check the pin on the brake and clutch trunnions; they're usually worn and it's a quick job to take some of the slop out of the pedal.
 
The MCs are aluminum.

The seat is protected - unlikely to be damaged. Seems more likely a problem with the pipe flare or the tube nut is cross-threaded or stripped.

If you're going to build/buy a new feed pipe, might consider trying it out on the existing MC before going to all the trouble of installing a new MC.
 
Last edited:
steveg said:
The MCs are aluminum. ...
Click to expand...

That's what I thought, too, until I received a steel--or iron, I really can't tell--one from Moss, I think, years ago. Wasn't happy with the horrendous weight increase (;)), but it's worked fine for years. IIRC, it came in a Lucas box, but who knows where it was made. Yes, the original in my BJ8 was Al, as is the clutch MC.
 
Thanks Jon, Steve and Bob,
I am going over to AH Spares tomorrow and will pick up a new feed pipe. I will also pick up a new master cylinder on a "just in case" basis. I will fit the new feed pipe to the "old" master cylinder and hopefully it will cure the leak. Steve the thread looks OK so it must be the flare. ( currently the clutch fluid level is dropping 1mm a day)
I am so looking forward to bleeding the thing yet again!!
cheers
Steve
 
Back
Top