Over the last two/three months I’ve had to top up the brake fluid on my Mk.1 on a couple of occasions where the level has dropped below the level so much that the warning light has come on!
But I could find no evidence of a leak - either from the master cylinder or any of the barake pipes I was able to see. It’s worth mentioning that the car never lost any braking performance.
I had the car serviced and MOT’d yesterday and mentioned to my garage (who I trust implicitly - they’ve been doing work on my cars for over 10 years now) and they promised to check it over for me; I must admit I was fully expecting to say they’d found a problem! But no problem was found - I specifically asked the question and spoke to the mechanic who’d done the work and he assured me that he could fid no evidence of a leak and that all the pipes - both flexible and the ‘rigid’ lines are in good order and that he checked all the other components as a matter of course.
The car breezed it’s MOT so (as you can imagine) I’m a happy chappie!
I suppose the only other thing of possible relevance is that I had the discs and pads replaced a few months back with EBC Turbo Grooves and Green stuff all round - could it possibly that it wass something to do with them bedding in? It does seem unlikely to me!
I just wondered if anyone’s got any thoughts on this.
What can anyone say, except if you are having to keep topping up the reservoir then it has got to be leaking somewhere. Even the experts should recognize this.
If it was mine I wouldn’t be happy driving your car until I found out what was going on. I would first of all clean all the connections at the caliper ends of the lines and also at the reservoir end,and make sure they are dry. Next,wrap toilet paper around each joint tightly and hold it on with a rubber band. Then sit in the car for 10 minutes with the engine running and keep pressing the brake pedal down for as long as possible to see if you get even the smallest amount of fluid onto the paper. After 10 minutes or so unwrap each joint to see if there is any trace of fluid. The amount of fluid you are loosing could be small enough to get washed off in the rain during the times between you having to top it up.
If this failed to find anything I would be very tempted to change the brake fluid completely. If you have automatic bleed nipples on your calipers then this is any easy job you can do on your own.
Just remember this, If you have an accident the mechanic is only going to say it was all OK on its MOT day.
The master cyl can leak fluid into the servo. There is no external evidence of the leak until the servo diaphram area is quite full of fluid. It can eventually show as white smoke in the exhaust. Not saying this is definately your problem, but it may be.
I absolutely agree with you that the fluid must’ve been going somewhere though (and I may have failed to say this in my OP) it does now seem to have stopped!
I’ve done all the normal tricks you suggest and tbh I was surprised this didn’t throw up any issues; my garage did also do a pressure test on the system that revealed nothing.
(As an aside I’m not exactly a mechanical novice; I used to race motorcycles, have done 24 endurance racing and the Isle of Man at 110mph+ so I have probably as good an appreciation of saftey issues as most!)
So I check the level virtually daily, look for even the slightest signs - it really is a puzzle.
I suspect I’ll finally go down the road of changing all the lines and fitting braided hoses (always a good choice - the change in feel is quite astonishing) and see what this reveals.
I’ve only experienced leaking into the servo once and that was a long time ago and not on a 5. As far as I can remember the only symptom was a continued drop in brake fluid level with no apparent external leaks. I caught it before I got to the white smoke in the exhaust phase but even so there was at least and inch depth of fluid in the servo when I removed and stripped it.
Same prob on my MK1 MX5, Disapearing fluid but no leaks in pipes, no change in brake performance.Eventually spotted brake fluid on rear inner tyre. It seems to be leaking slowly through hand brake lever arm at caliper. I think there must be a seal behind this lever within the caliper body that is starting to seep. This could be your problem.
Has anyone ever had to replaced this seal? Is it straight forward?
Thanks for the comments - I suppose the only way to rule this out is to strip the servo if the loss continues and no other component turns out to be the cause.
so (as you can imagine) I’m a happy chappie!