Brake Leak Mystery

[rdmstewa]

Hellooooo everybody! Please can you help me solve a problem that's defeated everyone that's looked at it so far?
A while ago I hauled the beastie out of the garage and noticed a pool of what looked suspiciously like brake fluid on the floor. A quick check of the master cylinder revealed that this is indeed what it was, as the cylinder was somewhat empty. I couldn't see where it was coming from so I put a piece of cardboard under the car to see where the drip was actually landing. That didn't help, so I took the car to Peter at Yorkshire Triumphs. This is where it got a bit strange, because he found that the system would maintain pressure without any leaks, but if the car was left standing for a period then the fluid level would drop. The drip didn't appear to be coming from anywhere near the brake system. So he suspects the master cylinder is the culprit (and I would imagine he's right), but before I start spending money on replacing that, I thought I'd share this problem with you and see if anyone else has had a similar experience. I should say that the m/c looks quite new, although it's probably a recon.
So - any suggestions would be very welcome! My thanks in advance.

Cheers

[Jonathan Lewis]

Just a thought, but have you checked the bottom of the servo body for signs of wetness?

It's not unknown for brake master cylinders to leak 'backwards', i.e. past the seal at the back of the bore where it mounts onto the servo body and picks up on the pushrod from the brake pedal.

[englishbull]

Hellooooo everybody! Please can you help me solve a problem that's defeated everyone that's looked at it so far?
A while ago I hauled the beastie out of the garage and noticed a pool of what looked suspiciously like brake fluid on the floor. A quick check of the master cylinder revealed that this is indeed what it was, as the cylinder was somewhat empty. I couldn't see where it was coming from so I put a piece of cardboard under the car to see where the drip was actually landing. That didn't help, so I took the car to Peter at Yorkshire Triumphs. This is where it got a bit strange, because he found that the system would maintain pressure without any leaks, but if the car was left standing for a period then the fluid level would drop. The drip didn't appear to be coming from anywhere near the brake system. So he suspects the master cylinder is the culprit (and I would imagine he's right), but before I start spending money on replacing that, I thought I'd share this problem with you and see if anyone else has had a similar experience. I should say that the m/c looks quite new, although it's probably a recon.
So - any suggestions would be very welcome! My thanks in advance.

Cheers

Just for the record.................Pete knows his stuff!!!!!!

[rdmstewa]

Thanks chaps - and I'm well aware that Pete knows his stuff, I don't doubt his diagnosis at all! I'm more curious to understand how the fluid can leak out of the back of the master cylinder into the servo and yet finish up on the deck under the middle of the bulkhead without leaving a visible trail...anyone experienced this phenonemon? And as I've started this, would anyone have a recommendation as to where I might get a new m/c? Pete tells me that the problem with recons is that they might have been bored out (no doubt to clean them up) and that the seals might not be up to it. Therefore no point in putting new seals in. I'm pretty sure that the one that's fitted is a recon, it actually looks quite new (having said that I've had the car for three years so it's older than that).

Cheers

[Alan Chatterton]

Malcolm,

From one Ex-Wakefield Lad to a current one!! (grew up in Sandal, Walnut Tree and 3 Houses regular drinking holes in my youth...........!!)

Anyway,

Unbolt the M/C from the servo, pull it forward a bit and stick your fingers to the bottom of the servo...... bet they come out wet!!

Only place it can be, then it gets burnt off by being dragged from the servo into the engine via the vacuum hose.

Rear M/C seal gone............. new one needed I suspect, but check the bottom of the servo after leaving it (ie, when the level drops) before you start the engine and the bottom of the servo will have brake fluid in it..........

Let us know, always keen to find out the truth when solved!!

[VitesseEFI]

The fluid will be going into the servo. Probably renewing the seals will suffice.

Nick

[rdmstewa]

Many thanks Alan and Nick - I'm getting it back from Pete tomorrow and will check this out. Actually, I suspect he already has, so we'll wait to see what he says.

Alan - small world, eh? The Walnut Tree was one of my favourite haunts - in the days of Watney's Red Barrel (I lived in Walton at the time)! I have a vague recollection of getting banned from the Three Houses - as I recall, one of our little group criticised the beer and upset the landlord. I can see the potential for a bit of reminiscing at this year's National...

[Alan Chatterton]

you have to go some to be banned from the Three Houses!!!! You sound like my kind of bloke!

I was drinking in the Walnut between oooooooooo, 1989 and perhaps about 1994. I even worked there when Dave was the landlord in the early 90's....... (he's the manager of Leicester Forest Services now on the M1!)

Pretty confident on the seals in the M/C....... new ones are pretty easy to find, there is one on ebay right now I think....... better new than just a re-seal kit?

There is another register member in Sandal called Jim...... has a white PI?...... do you know him?

[jimd]

I had 2000 estate that had a leak into servo from the m/cyl and it produced more white smoke than the Vatican chimney announcing a new pope. A straight swap with a spare, and job done.
Jim

[rdmstewa]

Alan - it was a long time ago! Somewhat before your time, in the late(ish) sixties. Ye gods, this is making me feel old. Which is justifiable, as I am!

Whilst discussing alcohol, perhaps I should tell you how I put the fish and chip shop in Wetherby out of action...or maybe perhaps I shouldn't...

Yes, I've met Jim at one of our local club shows - I joined him up to our club. If you want to see an example of a thoroughly amateur club website see http://www.ytcc.co.uk... All my own work, and no, I'm not giving up the day job!

Anyway, got the thing back from Pete. He's cleaned the back of the master cylinder and tells me that the fluid level hasn't dropped for a couple of days, so we'll see how we go. And then, while I was reversing out of his yard the wind caught the gate and I reversed into it. In front of the missus! So that's taken the rubber strip half off the quarter bumper, and having replaced that quite recently I know exactly what I'm in for now. B*gger.

No white smoke, though...