Master cylinder fluid leak

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muddy
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Master cylinder fluid leak

Post by muddy » 25th March 2018 - 5:47pm

You may have seen in my build thread that I fitted brand new front and rear brakes and a new master cylinder back in October. All products were CSP items.

I bled the brakes, after allowing the fluid to gravity feed through the master cylinder with all the nipples open in attempt to prime the master cylinder. I didn't do a bench prime.

I bled all calipers and the brake pedal was nice a firm afterwards.

However I noticed after a few days that there was brake fluid leaking from the master cylinder. The brake fluid was leaking from the rear most rubber grommet, up between the centre hole and plastic elbow.

I contacted CSP and haven't had much joy from them, problem being I bought the brakes in 2016 and didn't fit until a year later, so out of warranty.
So I have stripped and cleaned everything and refit it all for it still to leak. I've also bough a new rubber grommet and a new elbow in the hope that this would provide a better seal.

I thought this was just gravity fed and not under pressure, so I'm bemused why it's leaking up between. I'm sure that I set the pedal up correctly so that there was 1mm free play. If the pedal is putting pressure on the cylinder could this cause this? The front rubber grommet is fine and doesn't leak.

So since October I've not touch the car until this week because it's depressed the heck out of me, reference the above work that I've done.
I've almost gave up on the car, quite often want to torch it. It seems the car does not want to be finished which is a shame as it's not far away from being fully road worthy and ready for an MOT.

Any ideas guys? has any one seen this before? The only option I have left is to buy a new master cylinder at £170 :( :( :(

Cheers guys

ImageIMG_4375 by Craig Mudd, on Flickr

ImageIMG_4377 by Craig Mudd, on Flickr

ImageIMG_4376 by Craig Mudd, on Flickr
1971 VW Type 3 1600 TE Fastback. Body off Resto completed, now just bits and pieces and niff naff to do.
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Kai
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Re: Master cylinder fluid leak

Post by Kai » 25th March 2018 - 9:54pm

Sorry to hear of your troubles. I too have very much felt the same way with my project. As is the way £££ Will solve everything lol.

One thing to try, swap the rubber grommets and elbows front to back. This should either pin point the elbow and grommet as the fault or the hole in the master cylinder not sealing to the rubber grommet as the culprit.

The rubber hose has the appearance of fuel line, could also be suspect as there is proper brake fluid line.

For observing the leak, clean it up, dry it and cover it in talcom powder. Should help to locate the leak.

Should the grommet be loose in the hole, or the elbow lose in the grommet. You could get away with some type of sealant however I’m not able to recommend anything that would withstand the corrosive property of brake fluid. Maybe it’s not a concern for instant gasket, I couldn’t say.

You are correct in that this side of the brake system is non pressurised.

Best of lock sorting it

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Re: Master cylinder fluid leak

Post by broady_6 » 25th March 2018 - 10:18pm

It should be low pressure side as you say. so its just gravity that's pulling fluid through. Do you still have the blanks from when you bought it, as said above, but try blanking one port off. Sealant wise, you didn't hear it from me but LOCTITE SI 5980 will resist is. I don't know for how long, but it was a "shit or bust" repair at the side of the road to get us home, it did the job and it was a week or so sat in the garage before I had time to do a real repair. It was still working at treat. I cant give any more details on its life.

This is the right stuff for the low pressure side https://www.vwheritage.com/n0203501-bra ... e-vw-spare
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purplepeter
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Re: Master cylinder fluid leak

Post by purplepeter » 25th March 2018 - 10:24pm

As Kai says, check You've got proper brake hose & Those elbows look like beetle ones.. I thought Type 3 ones are/were 90 degrees to avoid the track rods fouling with the low pressure lines

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Kai
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Re: Master cylinder fluid leak

Post by Kai » 25th March 2018 - 10:44pm

purplepeter wrote:
25th March 2018 - 10:24pm
As Kai says, check You've got proper brake hose & Those elbows look like beetle ones.. I thought Type 3 ones are/were 90 degrees to avoid the track rods fouling with the low pressure lines
Yes this is a very good point. I encountered this with my 944 matercylinder. When the front end was jacked up and the wheels allowed to hang down the steering tie rod would touch the plastic elbow. Fortunately my car was lowered and didn’t touch when it was on the deck.

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muddy
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Re: Master cylinder fluid leak

Post by muddy » 26th March 2018 - 7:26am

Cheers for the replies guys.

So as to save further confusion, the rubber hose is in fact the correct blue cotton type, just with the blue cotton removed. It is brand new hose, but when cut the blue cotton frayed everywhere and was doing my head in so I removed it.

Regarding the elbow, this is what was supplied as new for the CSP 4 disc type 3 master cylinder. And the spare new one I bought to try was exactly the same. The elbow feeding the front most rubber is 90 degrees allowing clearance for the track rods. The rear one as per picture is 45 degree.

Clearance wise all is good when on the floor (and when jacked up).

I'm pretty reluctant to remove the front most rubber as this is fine and not leaking.

Regarding the leak, I know where it's coming from. Its coming up the centre hole between the rubber and the elbow. It's as if either the rubber is not seating properly or the elbow is not sealing within the rubber, or both. Seems strange that a new one of each hasn't fixed the problem.

I have some red grease for brake seals (For when you rebuild calipers etc) was toying with smearing some of this around the rubber and elbow to help.

Totally had enough now. :(
1971 VW Type 3 1600 TE Fastback. Body off Resto completed, now just bits and pieces and niff naff to do.
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Editor
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Re: Master cylinder fluid leak

Post by Editor » 27th March 2018 - 12:52pm

Easy enough to smear a bit of the rubber grease on and may help the grommet to seal better. I've not heard of the problem before. Obviously you've checked for bits of flashing on the grommets or obstructions in the m/c machining.
Dave.

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muddy
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Re: Master cylinder fluid leak

Post by muddy » 27th March 2018 - 8:02pm

Editor wrote:
27th March 2018 - 12:52pm
Easy enough to smear a bit of the rubber grease on and may help the grommet to seal better. I've not heard of the problem before. Obviously you've checked for bits of flashing on the grommets or obstructions in the m/c machining.

Cheers Ed,

I've done a load of internet trawling and there have been a few instances of this happening. Most of the time a new rubber seemed to have sorted their problems. Just curious that this is a CSP item and that it may be specifically built for them, so some machining may be off.

Comparing the original rubber to a newly bought rubber for a standard MC the original rubber is slightly longer (by mm's). I might just be reading into this too much.

The machining looks free from issues, there is a groove 3/4 down around the circumference which I suspect allows the rubber to sit into to make the seal. Still not sure how this would affect the fluid from creeping up the centre hole between the rubber and plastic elbow though.

I have noticed tonight that there is 2 machine holes at the base, they seem odd. one is on the edge/side wall, the other is off centre.

I'll attempt to try fitting it all back again, and if it still leaks I'll fire another email over to CSP (& machine 7 from whom I bought it from).

Otherwise I suspect I'm going to be £175 out of pocket for another one. :crybaby: :crybaby: :evil: :evil: :( :(

ImageIMG_4380 by Craig Mudd, on Flickr
1971 VW Type 3 1600 TE Fastback. Body off Resto completed, now just bits and pieces and niff naff to do.
Volksworld Magazine featured car 2013
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Kai
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Re: Master cylinder fluid leak

Post by Kai » 27th March 2018 - 11:36pm

If it’s creeping up the center hole, I would put it down to the fact that either the centre hole in the grommet is too large or the plastic elbow’s outer diameter is too small.

Could try heating the elbow with a heat gun and forcing something inside of tube part in an attempt to increase the outer diameter a smidge. Or sleeve the plastic elbow with some nylon pipe. Sounds like a terrible idea but with the amount of things I’ve had to overcome with my build this is a simple thing to try.

Or you could try a different source for the grommet and elbow.
Last edited by Kai on 30th March 2018 - 11:42am, edited 1 time in total.

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Re: Master cylinder fluid leak

Post by broady_6 » 30th March 2018 - 9:42am

Carbuilder solutions will probably be able to sort you out
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pmacs49
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Re: Master cylinder fluid leak

Post by pmacs49 » 30th March 2018 - 1:01pm

where did you get the master cylinder from. I had mine referred 4 yrs ago at passports £118 + postage,
I had the same trouble with mine, leaking on the top.
Its took a while to have the energy and inclination to do anything about it,
But i got some T1 seals from Just Kampers thought they might be too big, but they work, no leaks,
had to replace a rear wheel cylinder to get through mot. so did front brakes and rear shoes at the same time , it now has a 12 months ticket.

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muddy
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Re: Master cylinder fluid leak

Post by muddy » 30th March 2018 - 5:20pm

So I've visited the car today and noticed that the port has filled up with fluid, which is strange, even though nothing is connected on the gravity side (Rubber and elbow removed).

So I suspect there's an internal leak allowing the pressure side to get to the low pressure side.

I've also pulled the pedal cover and it is moist around the plunger :crybaby:

So I guess an internal seal is knackered. Not good for a new MC and especially a CSP item, which I assume is pretty good quality.

What do I do next?

Not sure whether a rebuild kit will sort it. Not sure whether I can be bother with the hassle.

Or bite the bullet and get a new one. But I've reluctant to get a CSP one.

It's a 4 disc set up, will I get away with just a standard dual MC?

Gonna pull the MC off to assess the damage. Really annoyed. No doubt in the process I'll have a problem with the copper lines etc.
1971 VW Type 3 1600 TE Fastback. Body off Resto completed, now just bits and pieces and niff naff to do.
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Kai
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Re: Master cylinder fluid leak

Post by Kai » 30th March 2018 - 7:33pm

Order another, send the old one back for a full refund :paranoid:

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sparkywig
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Re: Master cylinder fluid leak

Post by sparkywig » 30th March 2018 - 7:45pm

Kai wrote:
30th March 2018 - 7:33pm
Order another, send the old one back for a full refund :paranoid:
This.
Or get a Porsche 944 master cylinder if you have no luck with CSP.

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broady_6
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Re: Master cylinder fluid leak

Post by broady_6 » 31st March 2018 - 9:46am

muddy wrote:
30th March 2018 - 5:20pm
So I've visited the car today and noticed that the port has filled up with fluid, which is strange, even though nothing is connected on the gravity side (Rubber and elbow removed).

So I suspect there's an internal leak allowing the pressure side to get to the low pressure side.

I've also pulled the pedal cover and it is moist around the plunger :crybaby:

So I guess an internal seal is knackered. Not good for a new MC and especially a CSP item, which I assume is pretty good quality.

What do I do next?

Not sure whether a rebuild kit will sort it. Not sure whether I can be bother with the hassle.

Or bite the bullet and get a new one. But I've reluctant to get a CSP one.

It's a 4 disc set up, will I get away with just a standard dual MC?

Gonna pull the MC off to assess the damage. Really annoyed. No doubt in the process I'll have a problem with the copper lines etc.
One would assume that if it sat on the shelf as long as you say after you bought it (depending where it was stored) the damp has got in cause it to corrode and the first press of the pedal has damaged the seal as it moved over the rough corroded area. so it would be far easier to do what kai said than to try and re polish the bore
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Re: Master cylinder fluid leak

Post by Editor » 31st March 2018 - 11:41am

Are you sure that the M/C is compatible with a 4-disc system? The rear shoe system is designed to hold residual pressure to ensure the shoes don't have to move far to produce braking force, while disc calipers need to depressurise to let the seals pull the pads back from the discs to ensure the discs remain free to rotate.
Not sure if that is the answer, and the rear seal leaking sounds wrong anyway, but it does suggest pressure is building in the rear circuit for some reason.
The dual circuit M/C I have here in pieces has the small hole central in both front and rear circuits. That's the compensation port, and is uncovered when the piston is in its rest position to allow fluid back into the reservoir. If that can't happen, pressure builds as braking heat expands the trapped fluid and applies the brakes more and more as the fluid warms.*(see comment below). The rear hole is much larger and simply provides the main fluid fill to the cylinder.
Maybe carefully probe that hole to see if there's a seal below it. Since you've checked the pedal freeplay it should clear that hole, unless the design for rear drums needs to be different.

*I had that happen when I rebuilt the M/C with the wrong piston, which was minimally different in length. After a few miles pressure built and the brakes came on to the point I had to accelerate to go downhill! Opening the bleed valve produced a spurt of fluid. Problem found, but we were on the way to catch a ferry to Holland for a VW meeting - I drove very conservatively and changed it at the meeting - made a good sideshow!

I think you've done as much as you can, other than check if the M/C is suitable for 4-wheel disc brakes. If the hole has been drilled wrongly, you should get a suitable answer from the supplier.
Dave.

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purplepeter
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Re: Master cylinder fluid leak

Post by purplepeter » 31st March 2018 - 1:51pm

Just to throw it into the mix... I have experienced the grommet/inlet pipe failure when I got a bit too much pressure in the eezibleeder (about 7 years ago) Instant gasket worked & has continued to do so, though it doesn't look very elegant.

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937carrera
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Re: Master cylinder fluid leak

Post by 937carrera » 31st March 2018 - 2:34pm

If you are into the land of buying another master cylinder, then I would suggest using some Sikaflex PU adhesive to aid sealing the original inlet. Clean the hose / pipe with brake cleaner first then apply to the plastic tube and outside of the rubber grommet.

It's tough sticky stuff, strong enough to reinforce rubber engine mounts, suitable for lots of jobs :)
David
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muddy
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Re: Master cylinder fluid leak

Post by muddy » 31st March 2018 - 6:46pm

Kai wrote:
30th March 2018 - 7:33pm
Order another, send the old one back for a full refund :paranoid:
I think I'm past that point now. Stupidly (or not) I bought all the big stuff at the beginning of the resto, but didn't get round to fitting it all until after 12 months has passed.

I've been emailing Machine 7 and CSP since I noticed the leaking. They've both been positive in their customer service. I just haven't approached subject of the supply of a new one. I've been trying to fix the problem in situ, rather than having to strip everything down.
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muddy
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Re: Master cylinder fluid leak

Post by muddy » 31st March 2018 - 6:49pm

broady_6 wrote:
31st March 2018 - 9:46am
One would assume that if it sat on the shelf as long as you say after you bought it (depending where it was stored) the damp has got in cause it to corrode and the first press of the pedal has damaged the seal as it moved over the rough corroded area. so it would be far easier to do what kai said than to try and re polish the bore
It was sat in its original packing both in my conservatory and in my garage for 12 months or so. So this could have caused something to happen in both a cold and warm environment.
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muddy
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Re: Master cylinder fluid leak

Post by muddy » 31st March 2018 - 6:50pm

Editor wrote:
31st March 2018 - 11:41am
I think you've done as much as you can, other than check if the M/C is suitable for 4-wheel disc brakes. If the hole has been drilled wrongly, you should get a suitable answer from the supplier.
I ordered the specific CSP 4 disc MC. And looking they only do one for the Type 3 and its solely for disc set up. So I guess it's right?

How would it differ from a rear drum set-up?

Whether it is coincidence or not the leaking is from the portion that supplies the rear brakes.
1971 VW Type 3 1600 TE Fastback. Body off Resto completed, now just bits and pieces and niff naff to do.
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muddy
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Re: Master cylinder fluid leak

Post by muddy » 31st March 2018 - 7:09pm

Guys, can I just say a big thanks for the help and comments I've had so far. :thumbsup:

Any and all comments are helping me get through this, this has so far been the toughest part of the build and a test of my soul.

I know there are far worst things in the world, but sometimes the smallest of things can be really challenging.
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Re: Master cylinder fluid leak

Post by broady_6 » 31st March 2018 - 7:50pm

muddy wrote:
31st March 2018 - 6:46pm
Kai wrote:
30th March 2018 - 7:33pm
Order another, send the old one back for a full refund :paranoid:
I think I'm past that point now. Stupidly (or not) I bought all the big stuff at the beginning of the resto, but didn't get round to fitting it all until after 12 months has passed.

I've been emailing Machine 7 and CSP since I noticed the leaking. They've both been positive in their customer service. I just haven't approached subject of the supply of a new one. I've been trying to fix the problem in situ, rather than having to strip everything down.
What hes saying is order a new one and use that. But then send the only one back, pretending its the one you've just ordered and get a refund on it. ;)
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muddy
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Re: Master cylinder fluid leak

Post by muddy » 1st April 2018 - 5:18pm

broady_6 wrote:
31st March 2018 - 7:50pm
What hes saying is order a new one and use that. But then send the only one back, pretending its the one you've just ordered and get a refund on it. ;)
Unfortunately I still think I'm way beyond doing this, I've emailed Machine 7 and CSP many times over the last few months about this, so I don't think I will get away with such skulduggery. :unibrow: :paranoid: :paranoid:
1971 VW Type 3 1600 TE Fastback. Body off Resto completed, now just bits and pieces and niff naff to do.
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muddy
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Re: Master cylinder fluid leak

Post by muddy » 1st April 2018 - 5:28pm

Reluctantly I've stripped the brakes, and removed the master cylinder. Straight away I knew there was a problem when brake fluid leaked from the rubber boot which should be bone dry. The internal seal is definitely leaking :(

Brake pedal rod wet with fluid

ImageIMG_4384 by Craig Mudd, on Flickr

Rubber boot wet through

ImageIMG_4385 by Craig Mudd, on Flickr

Leak from internal seal
ImageIMG_4386 by Craig Mudd, on Flickr


I've sent Machine 7 a follow up email and told them about this latest discovery. I'll see what they come back with.

Annoyingly, this is stopping me finishing off the rest of the build. I can't fit the petrol tank, I can't fit the air ride, I can't set the ride heights. No doubt there's more problems to come.
1971 VW Type 3 1600 TE Fastback. Body off Resto completed, now just bits and pieces and niff naff to do.
Volksworld Magazine featured car 2013
Instagram: @type3.fastback

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