Brake Master Cylinder Query

Adding a visual of the current MC installed, originally by VS when the car was new… likely a standard OEM re-pop, 19.05mm ID.

all MC surfaces are dry to the touch… but pan under MC is covered in brake DOT3 fluid, about 2oz.   Upon closer inspection of the picture, I may need to check out that plug bolt… im wondering if that may be the source of the leak… it has what appears to be some wet road dirt around it,,, but when I tour h around yesterday it was all dry…  I may need to be more careful checking,,

I may have missed this, but since the brakes feel string, could it be a leak between the reservoir and the MC?

Thanks Lane,  that was my first thought as well…     The two lines coming down to the MC from the reservoir are dry and dusty.  They are the two lines pictured on the right hand side of my pictures, held by the O clamp visible about half way down the picture frame on the right hand side.  Also dry and dusty where they connect at the MC.

this one is a brain teaser….  That’s why I was wondering if thermal contraction of any/all the materials could possibly be the culprit if a particular plug/ connection is borderline loose.

we cleaned the pan dry after the leak 2 years back…. And this is the first time I have seen any leak evidence since ( and I have ben checking  every couple of weeks for safety since it’s in my watch list since the first time this happened.  The two experienced local mechanics ( really old school experienced + 65 year old local VW SMEs could not track it down…

Is the brake fluid old (2+ years)?  Brake fluid is hydroscopic (absorbs moisture) just sitting in a garage.  That water could freeze and expands when it does.  That would explain seeing fluid when its been real freezing cold.  Clean that area really well - with engine degreaser or simple green.  That bolt does look like a leak candidate.  Once area is really clean you can see if there are new wet leaks.  The steel line to rear usually runs along the driver's side along the lower tunnel (and not inside the tunnel).

For giggles, attached is a picture of the passenger side of the pan— between front wheels under gas tank., … the line coming down the middle is the gas tank fuel line…  I wondered if I had a gas leak,,. But the liquid stains do not taste  or smell like gas. … I smells more like the brake fluid…. But I have no idea how it would get to that side of the túnel… unless something is squirting from somewhere.

im guessing I will need to check all connections…. Then clean all surfaces dry with degreaser, and then see where this leaking is coming from…

and another pic of area around the MC

Many thanks @WOLFGANG The brake fluid is now 2 years 5  months old… so that could be the culprit.   We bled the entire system after this last happened two winters back ( now entering our 3rd winter).  And in the PNW humidity/moisture content is high.

will try that.   One Q- I was thinking of updating to DOT4 from DOT3 as I read somewhere it’s less prone to moisture absorption.   Is this something you guys know anything about?  Do our systems accept this more modern standard fluid?

I did top of the fluid yesturday after I noticed the fluid loss, and before my various test drives.  Also, I laid out paper towels  in both pan areas - held in place with magnets- to see if anything leaked over night, and  during subsequent test drives today, and nothing.  Paper towels are dry.  

.

Are you sure it's brake fluid? On the passenger side, too?

Any signs of rodents (who seek indoor shelter in colder months)?

The brake fluid level in the reservoir gradually drops over time as pads wear and calipers extend further to contact discs.

Thank you @Sacto Mitch .  The passenger side too…does have me scratching my head.

Fortunately no sign of rotens in the car, or inside the garage.  I keep it bare and clean with plenty of traps/poison to retire an army of rotens outside and inside the garage.  No signs, dropping, or carcasses found during my inspections this week.

On the brake fluid front;

1) between drives I take a picture of the reservoir so I can keep track of the level between drives and when stored.   The ~2oz drop was as compared to the level/picture I took on November. 29th when I parked the car… so the drop was while the car was stored/parked between Nov 29 and Dev 24.   Super strange.
2) the small fluid amount pooled on both sides had the same color, smell.  Not gas, and I don’t have any other fluids that run through that area of the car.  

Super strange,

The press-fit plastic cap* on the front part of the MC is loose or cracked. It’s dripping under pressure from the remote reservoir, which is why the brakes work fine. Just replace that, and maybe put a spare sender where that square head plug is while you’re at it.

good luck!

*this I think https://www.jbugs.com/product/...LZXOt24aAqSSEALw_wcB

Thank you  @edsnova.

quick question… when you reference “ the front part of the MC, do you mean #1 or #2 in the below picture?  I would assume #1… forward most in the car…. But wanted to ask so I didn’t  guess wrong.

I ask as a learning opportunity for me;  Is the darker color- non corroded surface  what leads you to conclude this?
——-   both the dark and corroded surfaces feel dry to the touch, and to the paper towel…and the dark surface was the original MC color.   I would have guessed it would have been the corroded side that maybe was at one point exposed to some fluid… but I admittedly know very little about these MCs.

the reason why I ask is because when you mentioned a potential loose or cracked plastic connector, my mind went to a possible squirting scenario that could have sprayed fluid when the MC was under pressure on top of the tunnel…  areas circled in below picture…. Which could possibly be coming from the #2 connector…. And squirting over to the other side of the tunnel.as well… explaining the wet area on the other side.  But… sooo strange that  the fluid is only being lost in bulk when the car is parked in the garage in cold-near freezing/freezing weather.  Maybe I can recudiste my daughter to pump the brakes while I  watch film the MC in action… maybe I see where this leak is coming from

Also… if I could trouble you with one last question on your spare sender recommendation- would you recommend connecting it in series, or parallel to the existing sender?   Or just installing a spare sending unit in the empty plug, but keeping it disconnected from the electrical system…. So in the event the original ever fails then just move the electrical connections over?   Again, I would assume the latter… but i’m wrong most times… which is why I tend to learn by fixing things I break…so figured I ask. ;-)

love the learning process associated to these cars.  Thank you for sharing your knowledge., and thank you again for your help.

Luis

“would you recommend connecting (the spare stop light switch) in series, or parallel to the existing sender?”

Connect it in parallel - same wire to like terminals on the switches.  That way, when one fails (and it will, it’s just a matter of time) your brake lights will still automatically work through the other one.  They only have two failure symptoms - either they leak or the switch stops working.

Here's a good J-Bug article on the master brake cylinders.  Only thing not covered is the brake circuit test button which US bugs had on the dash (and Speedsters seem to eliminate).  That dash button would indicate if there was a pressure difference (a failed wheel cylinder or brake line leak) between the 2 chambers.  (So some brake switches had 2 and others have 3 wire connectors - the 3rd wire is for the dash switch/light or if 2 wires the 1st brake switch is used for the dash indicator (so not needed replica Speedsters don't use the dash indicator).

The way I read this and your photos - the front most circuit is for the front brakes and the rear/middle one is for the rear brakes.  The front brakes do 70% of the braking (hence disc brakes are preferred). 

Single vs. Dual Circuit Master Cylinders | JBugs.com

Thank you @Gordon Nichols and @WOLFGANG. Much appreciated.

Interesting bit… buying a new Brazilian or Italian MC will run shy of ~50$ including shipping.  Buying just the plastic connectors and fresh rubber grommets ( 2 each) w;/ shipping  only saves 10$…

Will order two fresh brake switches as well…as long as I’m having to tinker, may as well put in fresh parts.

Thank you again for all your help/thoughts.

i was really hoping to avoid any winter car projects since the cars has been running trouble free the last two seasons… but I guess it’s inevitable, and part of the Madness that are these cars!

Front is front. Yeah my guess is based entirely upon the dark stains that indicate freshness. I could be wrong but it’s easy enough to check. Just drain the MC reservoir and pull the plastic pieces and rubber grommets. I’d never heard of one leaking before but these are aftermarket Bug parts so…

Thank you….  This will be an interesting science project.  Looking at the reservoir and around the MC today… my fluid level keeps dropping… below drop from 12/24 to 12/28 while car parked…. but the paper towels around the MC are dry.  Looked at the four corners, and related connections near/around the wheels again today and all dry.     Will need to see how much more it leaks to see where it drains to….Super strange.  Where is the fluid going while the car is parked?

parts ordered—- replacement plastic connectors & rubber grommets, two new brake switches and a new MC  just in case. ( figured may as well have all the parts in hand in case something goes sideways - and while everything is 15-30% on sale).  If after the bits are replaced this thing is still loosing fluid… then I wonder if the main line has sprung a leak somewhere… though i inspected again today and carpet is dry along where the line runs to the rear— don’t want to rip up the carpet unless I really have to, and line to the corners seems dry as well.

now just have to wait for parts to arrive,,,

Just for the hell of it, go into the pasenger compartment and remove the cleavis pin between the brake pedal and the MC. It should pull out/ It goes into a bellows (looks like a mini CV joint boot).  See if there's anything leaking from the MC back out past the main seals into that bellows/boot. Your brake pedal is solid, so it's unlikely, but not impossible.

And once you check JMMs thought - check carpet along that side of the tunnel.  On old VW's the steel line rusts there since bugs took outside abuse.  New replacement lines are generally shipped in 2 pieces with a connector - that connector could leak.

Maybe have someone push hard on the brake pedal and listen/look for leaks. There are pressure bleeders that you place on the reservoir (in place of cap) and it pressurizes the system - that would greatly help locate your leak!

@JMM (Michael) Michael I think you found it…. I had totally missed it since I looked at the top of the boot, and the carpet felt dry… because in this area of VS its double layered ( two pieces overlap covering the bottom of the boot and hiding any wetness).

Upon pealing the two layers of carpet back… presto, bottom of boot had leak tracks and lower layer of carpet was wet behind the pedal cluster… .  Looks like MC seals may have started to fail, and the cold temperature contraction of material allows the system to flow more freely than in the warmer months.  Bugger!!!

also, on the other side of the wall… I can now see a little new seepage under the paper towel coming from where the MC goes torough the footwell wall. Now noticeable after having degreased/cleaned the area earlier today.

still not sure how it may have gotten to the other side of the car.. the passenger side… but will start by addressing this finding and go from here,

many thanks!!!

In my experience, brake fluid has uncanny wicking abilities.

Danny has got that right, sh*t gets everywhere and anywhere.  At least you've got a new one already coming! Plus you can add the second switch, flush out the old fluid, and start spring with good brakes. It's not a hard job, just tedious and covered with DOT 3.

Brake fluid is a lot like Anti-Seize cream.  

You're going to get it all over the place anyway, so you might as well just smear it on your hands and face (and hair) to start and get it over with.    😜

@Gordon Nichols posted:

Brake fluid is a lot like Anti-Seize cream.  

You're going to get it all over the place anyway, so you might as well just smear it on your hands and face (and hair) to start and get it over with.    😜

And it smells so good!

Thank you everyone… appreciate everyone’s help.  This leak was driving me nuts last two days and I could not just let the car sit leaking without knowing and doing something about it.

just finished draining the reservoir and the lines leading to the MC to  keep the mess in the car while I wait for the parts to a minimum.  

These are the projects where I wished I had a small lift and a larger/heated garage at home to make working  on the car a bit easier. But we are lucky to have a “ do it your self shop”. near by.   I imagine when I have all the parts in hand I will take the car to The Shop (https://theshopclubs.com/seattle/ - a car club not far from the house, and reserve a lift  work area for the weekend to crank this out… they have all the tools, and bleeders needed, and a mechanic on hand ( for a fee charged on 30min intervals) to help me if I get in trouble.  The lead mechanic is good… but he is a British car specialist, though he maintains many many air cooled P-cars, VWs and some replicas as well… and teaches a metal working class and basic maintenance classes that’ are awesome.    

With all the local old school VW  guys now retired applying those lessons they shared and ALL your helpful guidance is now the only way to keep this baby running tip-top.   I dread the day something goes sideways with the engine or transmission.., hopefully by then someone will stand out locally as the VW whisperer filling the void.  

thanks again for all your help.  You guys are AWESOME!!

@Lfepardo wrote about his garage repair space;

“The lead mechanic is good… but he is a British car specialist, though he maintains many many air cooled P-cars, VWs and some replicas as well…”

Never fear, Luis.  Lucas never figured out how to add “smoke” to the British hydraulic systems, like brakes, as they did in electrical systems, so whatever experience your mechanic has is still good for your car.   😉

Hah!!!… but they keep trying.   The guy did get my Austin/MG running back like when it was new, and still the speedster is more fun to drive.

I may have overcompensated… ordered a Brazilian and a German MC, all related installation hardware, new pads/shoes, fresh brake hose lines, rear drum cylinders, etc  ( in case any of they key components needs replacement/refreshing,)… may as well check and freshen up  anything that looks aged in the braking system.  The car is now +10, and other tHan changing the brake fluid a couple times  and adjusting the rear pads, I have done little to it (has not really needed much), since the disk brake/5-wide update on 2016.

as long as the mess is made in someone else’s garage the wife is happy.  

Great news and many thanks to Michael Pickett for guessing correctly.

Don’t forget to prime the new M/C before you install it.

Ok, so I think there is some bad mojo working here in this string. I had to put some Christmas lights away so I pulled the speedster out to get to the attic and take it for a spin. Walking back into the garage and what do I see? Brake fluid all over the floor just like Lfepardo. What’s going on here friends. Please, stop talking about this stuff. I can’t afford a new engine or brakes or transmission. I was just thinking to myself that I’ve been so fortunate as not to have any problems for a while. It’s running so great. I’m taking it in for a tune up on Thursday just because you’re supposed to. Was it your fault for talking about it or was it mine for thinking these utopian thoughts? Damn my eyes!

Tom🥺

This sounds like a perfect example of Einstein's Quantum theory of "Spooky Action at a Distance", whereby your car and Luis' car are somehow engaged in a Quantum entanglement such that whatever happens to one car, Luis' in this case, happens to the other with no other outside action.  Einstein couldn't 'splain it, so he just called it "Spooky".

Erwin Shrödinger later postulated (about the time he was trying to observe his famous cat) that if you try to observe this entanglement first-hand, just the fact that you're looking at it will break the entanglement.  This will leave your car to fend for itself if Luis decides to swap out his leaking Master Cylinder, so you might as well get one, too, 'cuz it ain't gonna re-entangle, all on it's own, at this point.

Good luck, and hope your car doesn't fancy an entanglement with another, very soon.

And stay away from Radium watch faces, too.......

Hahahaha! To quote one of the greats, Mr Feldman said: “Too late”

Tom

Tom, I”m  sorry to hear about  your leak.  Funny enough, I was thinking the same thing after my thanksgiving drive… “ how sweet it was to have the car running tip-top all summer without any surprises”.   Wife told me such thoughts just jinks things.  Spooky as Gordon quotes!

Only upside is that all retailers are running 15-30-47% sales this week…. So you can get an Italian made MC for under 40$, or a German one for under 100$.  ( didn’t find any Brazilian made ones other than at SoCal imports… and they were not on sale) . And German made switches for under 10$ ( basically the pricing of non discounted Chinese parts any other time of year).    Most mechanics will let you bring your parts in… if you don’t they typically will charge you MSRP with a little premium for the part they have on the shelves ( if they have it).  Old school guys will typically keep Euro parts on the shelves, but new school shops around here tend to stick the Chinese parts.

Let me know if you need any links… I sourced my Italian one form CB performance, and the German one from Cip1…. Though the pricing was the same for both at Jbugs, Wolfsburg but  picked Cip1/CB because delivery timing shipping was less/closer from CA/Vancouver.  Could have sourced all from Cip1 or Jbugs ( two of my go to shops lately). but I like supporting the CB folks when I can as well.

interesting side note- the British car forums chat about this (cold temperature and MC leaking as a sign the MC seals are starting to go). in great detail, specially the Land Rover groups where cars sit outside.  But nothing on VW/Pcar forums… I guess those cars sleep in heated garages now days ;-).

@Lfepardo posted:

...One Q- I was thinking of updating to DOT4 from DOT3 as I read somewhere it’s less prone to moisture absorption.   Is this something you guys know anything about?  Do our systems accept this more modern standard fluid?...

You were asking about brake fluid- through the magic of Google, I got this-

I flushed and replaced with DOT 4 with no ill effects back in 2022. Just a data point.