Brake Fluid Underneath Master Cylinders

[david.g.chapman]

A strange one this...

I felt the bottom external surface of both my early +2 clutch and brake master cylinders today, and there was a trace of brake fluid there. The car had been driven occasionally over the winter, and it has been some time since I last looked. However, brake fluid seems to slowly build up in the area.

The outlet pipe joints do not seem to be leaking, but there is a trace of fluid underneath the metal caps (no plastic extension reservoir on this car). It looks as if fluid is seeping out of the hole in the centre of the cap, or from the cap thread, and working its way down the outside wall of the cylinder to the bottom. I normally keep the fluid level about 7-8mm down from the top.

There is no significant loss of fluid.

Has anyone else come across this? Should the centre hole in the cap have a metal lanyard fitted to it, which would partially block the hole?

Dave Chapman.

[alexblack13]

No. It's a breather hole. The fluid will be leaking past the rubber seal.

Have you replaced the cap(s) recently per chance? There are some poor quality items out there which do not tighten well / fully and tightening with any 'tool' makes for real difficulty in removing them.

I have had the same problem. Slight leakage and the only way to stop this is to get decent caps and tighten them well.

Alex B....

[UAB807F]

Hi Dave,

I had the same problem, a nice clean outlet pipe joint but every now and then I'd feel traces of what felt like brake fluid on the bottom of the cylinder. The same on both brake & clutch.

Like Alex I put it down to a poor seal at the cap allowing light seepage when you were driving. Not enough to make you think you needed to top up the reservoirs, just enough to make you wonder about it. Last year I went to a remote brake reservoir plus a new clutch m/cyl, and so far the problem hasn't come back. (tempts fate ! )

Brian

[Robbie693]

I get this on my Plus 2, usually after i've had the caps off. I have the Sovy unit fitted and the seal can leak if it's not in perfect condition. As Alex says, the screw-on caps leak unless you really tighten them. Then you have trouble getting them off again!

Does the leak appear when you haven't driven the car? I am thinking that fluid sloshing around whilst cornering makes it's way past the cap seals. If it's a leak from the union then standing on the pedal would cause come seepage. I find if it's the piston seals that have gone the fluid drips on the floor inside as the open end is inside the pedal box.

Robbie

[richardcox_lotus]

I've had this on the Sprint as well. Sometimes I'm not sure if it's brake fluid or light petrol spray from the underside of the webers or spit back dripping out from the air box or light oil spray from the front cover or ..... Or....

However whenever I've checked the fluid level it seems fine.

I agree it's probably the cap seal.

Regards
Richard

[RichardHawkins]

Brian,
You mention remote reservoirs. I am rebuilding my Elan S4 fixed head and would like to fit a remote reservoir. Which reservoir did you use, and are you pleased with it?

I am also in Lincolnshire, do you go to the Lincolnshire Club Lotus monthly meetings?

Regards,
Richard Hawkins

[UAB807F]

Brian,
You mention remote reservoirs. I am rebuilding my Elan S4 fixed head and would like to fit a remote reservoir. Which reservoir did you use, and are you pleased with it?

I am also in Lincolnshire, do you go to the Lincolnshire Club Lotus monthly meetings?

Regards,
Richard Hawkins

Hi Richard,

A picture is easier than a description - the only things to add are I bought it from Ebay and the bracket is home-made. But it is certainly not for anyone wanting to retain the original underbonnet appearance.

http://www.martley.plus.com/2011/uab10.html

It's a standard reservoir with 2 internal compartments, complete with a modern "low fluid" switch. Works well but as I say, isn't even remotely original.

I'm not in Club Lotus any more, in fact not for several years now, so I must admit I didn't even realise they had meetings in Lincolnshire. Out of interest, where are they ?

Brian

[david.g.chapman]

Thanks for your replies.

I have waited this long to see if there is any leak while the car is not used. The answer is no.

There is no leak to the interior of the car, so this looks like the cap seals/cap alignment on the cylinders. I have never changed the caps since I got the car in 2001, so this might be a good time.

Cheers,

Dave Chapman.