Master cylinder fluid leak

Come here to ask for technical help and advice
User avatar
muddy
Posts: 134
Joined: 23rd September 2016 - 5:23pm
Location: Mansfield

Re: Master cylinder fluid leak

Post by muddy » 27th April 2018 - 6:30pm

Just a tiny update. Having removed the MC it was obvious that the internal seal had gone, leaking into the subframe, I guess it was putting some kind of pressure on the low pressure side.

I've returned the MC back to machine 7 for them to send back to CSP for investigation. They confirmed that I'd receive a refund (or replacement) if a defect is found.

In the mean time I'll order a new one up to get the build finished (i hope).

Other than doing a bench bleed (Which I'd rather not do) does any one have any advice when I fit the knew one.

My routine:
1. Ensure the pedal free play is correct ~1mm
2. Fill brake fluid reservoir, open all 4 bleed nipples and allow the fluid to gravity bleed through all nipples.
3. Tighten bleed screws once fluid is seen.
4. Bleed each caliper in turn through the normal process of pumping and checking for air.

In terms of the x2 pressure switch placement I had fitted them at the 2 lowest ports, which i think I read somewhere was the best place. Although I don't have many other options as the side ports feed the front and rear brakes.
1973 VW Type 3 1600 TE Fastback. Under restoration

User avatar
Editor
Posts: 5450
Joined: 10th October 2004 - 8:52pm
Location: Pensford, Bristol
Contact:

Re: Master cylinder fluid leak

Post by Editor » 28th April 2018 - 2:18am

The drillings in the brake switch holes are larger than the holes to the brake pipes. I've heard it makes it less likely for air to remain in the switch.
Dave.

User avatar
muddy
Posts: 134
Joined: 23rd September 2016 - 5:23pm
Location: Mansfield

Re: Master cylinder fluid leak

Post by muddy » 7th May 2018 - 11:30am

Does anyone know where I can get my hands on a bench bleed kit?
1973 VW Type 3 1600 TE Fastback. Under restoration

User avatar
muddy
Posts: 134
Joined: 23rd September 2016 - 5:23pm
Location: Mansfield

Re: Master cylinder fluid leak

Post by muddy » 30th May 2018 - 6:22pm

An update.

Got a refund from Machine 7 for 1st master cylinder. CSP never reported back what the issue was. :evil:

The 2nd master cylinder I bought was fitted, bled and failed. When the brake pedal was pressed down, brake fluid would leak from a vent hole at the base of the master cylinder.

Back to Machine 7, who have quizzed CSP again. CSP came back and said it's likely an internal failure of the master cylinder :evil:

They are going to send a 3rd master cylinder out to me to try, but I don't have much confidence that it will work. I was hoping CSP could pin point the reasoning behind the failures, I'm not that bothered if its because of something that I've done, as long as I can fix it.

I'm at a point now that I'll be pulling the old drums etc from the storage box and fitting them back. Problem there is, I need to spend more money on master cylinder, brake cylinders, pads, 4x130 to 5x130 adaptors etc. :evil:

Machine 7 have been great though in their communication and are trying their best to get this all resolved. It has been refreshing to have great customer service.
1973 VW Type 3 1600 TE Fastback. Under restoration

User avatar
broady_6
Posts: 1631
Joined: 13th January 2009 - 9:55pm

Re: Master cylinder fluid leak

Post by broady_6 » 30th May 2018 - 9:52pm

you may need to build a bench set up so you can see all the components at one to work out which one is causing the issue.

At least your betting the help from the supplier :)
The sultan of swing

User avatar
sparkywig
Posts: 317
Joined: 28th August 2013 - 12:49pm

Re: Master cylinder fluid leak

Post by sparkywig » 31st May 2018 - 1:42pm

sparkywig wrote:
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.
At the risk of repeating myself, spend £60ish on a Porsche 944 master cylinder instead.

User avatar
muddy
Posts: 134
Joined: 23rd September 2016 - 5:23pm
Location: Mansfield

Re: Master cylinder fluid leak

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

sparkywig wrote:
31st May 2018 - 1:42pm
sparkywig wrote:
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.
At the risk of repeating myself, spend £60ish on a Porsche 944 master cylinder instead.
Sorry Sparkywig, wasn't ignoring your advice. Obviously I need to try and keep on the path I'm on with the CSP master cylinder. If the 3rd one fails, I'll give the 944 one a go.

Out of interest do you have experience of fitting a 944 master cylinder? Are there many modifications to make or is it a straight bolt on job?
1973 VW Type 3 1600 TE Fastback. Under restoration

User avatar
sparkywig
Posts: 317
Joined: 28th August 2013 - 12:49pm

Re: Master cylinder fluid leak

Post by sparkywig » 31st May 2018 - 7:44pm

It's a straight replacement for the type 3 master cylinder, just need to adjust the pushrod a little, and add a tee piece for the brake light switch.

Image

You'll also need to either add a tee into the low pressure brake line from the reservoir or fit a Beetle dual circuit reservoir and another brake line to the master cylinder.

Image

User avatar
muddy
Posts: 134
Joined: 23rd September 2016 - 5:23pm
Location: Mansfield

Re: Master cylinder fluid leak

Post by muddy » 31st May 2018 - 8:31pm

sparkywig wrote:
31st May 2018 - 7:44pm
It's a straight replacement for the type 3 master cylinder, just need to adjust the pushrod a little, and add a tee piece for the brake light switch.


You'll also need to either add a tee into the low pressure brake line from the reservoir or fit a Beetle dual circuit reservoir and another brake line to the master cylinder.
Really appreciate the detail. I've actually been reading up on it this evening and it looks pretty straight forward. And there are 4 second hand master cylinders on ebay for £40. :unibrow: So i'll get one purchased to give a try.

My only dilemma is the brake line configuration that I already have, it would mean me trying to bend my rear brake line to now try and sit into the rear most port (where you have your t-piece for brake switch). I can make some new front brake lines to fit into the front ports (Nearest the bulk head), so that's no issue.

It's already dual gravity fed, so that's covered.

Were you not tempted to put a switch in the front brake circuit? I have 2 switches, for front and rear.

I guess you have rear disc brakes fitted. And you have no issues? Passes brake tests ok?

Thanks again. Feeling better about this already. :) :) :) :)
1973 VW Type 3 1600 TE Fastback. Under restoration

User avatar
muddy
Posts: 134
Joined: 23rd September 2016 - 5:23pm
Location: Mansfield

Re: Master cylinder fluid leak

Post by muddy » 31st May 2018 - 8:32pm

@ Sparkywig

Sorry can you confirm that your front brake circuit lines are connected to the ports closest to the bulkhead?
1973 VW Type 3 1600 TE Fastback. Under restoration

User avatar
broady_6
Posts: 1631
Joined: 13th January 2009 - 9:55pm

Re: Master cylinder fluid leak

Post by broady_6 » 31st May 2018 - 10:06pm

muddy wrote:
31st May 2018 - 8:32pm
@ Sparkywig

Sorry can you confirm that your front brake circuit lines are connected to the ports closest to the bulkhead?
Ive got a 944, I can send you any photos you need of the master cylinder. Its at the top of the engine bay. The one thing to be careful of is, the second hand cylinders are famed for pitting and not sealing very well. (ask me how i know?) I dont know if its still true, but a few years ago the rebuild kits were pulled from sale because lots of people did a home rebuild and it failed quite quickly because of the rough cylinder bores. And the seal manufacture was getting sick of dealing with claims. So you either got lucky second hand or you bought new. This may no longer be the case. but I havent checked recently
The sultan of swing

User avatar
Kai
Posts: 367
Joined: 3rd June 2007 - 12:40pm
Location: Surrey

Re: Master cylinder fluid leak

Post by Kai » 31st May 2018 - 10:57pm

muddy wrote:
31st May 2018 - 8:32pm
@ Sparkywig

Sorry can you confirm that your front brake circuit lines are connected to the ports closest to the bulkhead?
Front brakes are connected to the ports closest to the bulk head ( larger cylinder )

I would advise running two brake lights switches with a 944 MC. Otherwise the brake light switch may come on late and be rather faint.

Yes it’s likely you will be required to purchase the Porsche 911 MC rubber grommets for fluid feed lines into the 944 MC.

I have a distant memory of lengthening the push rod with the 944 MC.

User avatar
sparkywig
Posts: 317
Joined: 28th August 2013 - 12:49pm

Re: Master cylinder fluid leak

Post by sparkywig » 1st June 2018 - 2:39pm

muddy wrote:
31st May 2018 - 8:32pm
@ Sparkywig

Sorry can you confirm that your front brake circuit lines are connected to the ports closest to the bulkhead?
Yes

User avatar
muddy
Posts: 134
Joined: 23rd September 2016 - 5:23pm
Location: Mansfield

Re: Master cylinder fluid leak

Post by muddy » 1st June 2018 - 4:46pm

Thanks guys for all the help.

I've ordered a second hand one off of eBay as a back up if the third master cylinder doesn't work.
1973 VW Type 3 1600 TE Fastback. Under restoration

User avatar
muddy
Posts: 134
Joined: 23rd September 2016 - 5:23pm
Location: Mansfield

Re: Master cylinder fluid leak

Post by muddy » 16th June 2018 - 10:12am

Porsche Master cylinder was delivered.

I bench bled it on Wednesday, and it was fine. No leaks, and no air leaked back into the lines.

All good so far.

Spent yesterday making new front brake lines to fit to 3 way joiners so I can retain the 2 brake master switches.

This weekend I'll bleed the brakes. Fingers crossed. My 8 month saga may end :?:
1973 VW Type 3 1600 TE Fastback. Under restoration

User avatar
broady_6
Posts: 1631
Joined: 13th January 2009 - 9:55pm

Re: Master cylinder fluid leak

Post by broady_6 » 16th June 2018 - 12:11pm

:D :D
The sultan of swing

User avatar
muddy
Posts: 134
Joined: 23rd September 2016 - 5:23pm
Location: Mansfield

Re: Master cylinder fluid leak

Post by muddy » 16th June 2018 - 6:54pm

So with the master cylinder fitted along with all new brake pipes and the brake switches I Bled the system today and no leaks and no issues were evident......so far :?: :?: :?:

When the pedal is released I can see the fluid release back into the reservoir, unlike the CSP items which I think was the route problem.

So I'll keep any eye on everything for a week, and then hopefully I can get everything else bolted back in.

However, one solved problem brings new challenges. I re-fitted the steering track rod and it rests on the further most elbow and hose. When the steering is turned it wants to rip the elbow out. Problem being that it's a beetle elbow at 45° where the normal type 3 elbow is horizontal and so wouldn't have been a problem.
Now I know this will only be an issue when the car is raised, I believe the track rods will raise upwards when the car is lowered under it's own weight. But I want this car to pass an MOT and therefore this issue needs to be fixed, plus I''ll forget about this issue next time I jack the car up and move the steering.

So, I think by moving the elbow 90° to the right and putting a longer hose between the elbow and metal pipe I can possibly route it all out the way of the tie rod.
Just means I have to drain the system and then re-bleed again :crybaby:


ImageIMG_4541 by Craig Mudd, on Flickr
1973 VW Type 3 1600 TE Fastback. Under restoration

User avatar
muddy
Posts: 134
Joined: 23rd September 2016 - 5:23pm
Location: Mansfield

Re: Master cylinder fluid leak

Post by muddy » 17th June 2018 - 4:40pm

So it seems to have behaved itself overnight.

Today I've drained the rear most gravity line and extended it so that is snakes around avoiding the tie rod.

I hope this doesn't affect the way it all operates.

re-filled and then re-bled. All good so far. I'll keep an eye on it every day this week. If all is well I'll be able to get the tie rods and fuel tank fitted fully.

ImageIMG_4544 by Craig Mudd, on Flickr
1973 VW Type 3 1600 TE Fastback. Under restoration

Post Reply