Brake Master Cylinder Leaking...Now What?

[DavidProehl]

I discovered today that my brake master cylinder, which I replaced with a new part 3 years ago, was leaking. Must have started over the winter while in storage.

I have now promptly removed it. It looks like the issue may have been the seals at the top? You can see dark trails running from the top seals down in the below photos, although the seals look fine to my untrained eye.

So now my question is, how do I fix the damage? Here is what I understand are my next steps and I want to confirm them with all of you here:


Rinse out entire area with soapy water to clean out leaked fluid
Use some type of epoxy/pait stripper (recommendations?) to clean affected areas.
Re-paint with POR-15
Spray over POR-15 with rustoleum that matches existing epoxy
Reinstall cover plate
Replace brake master cylinder (recommendations on vendors? Can't say I'm impressed with a 3 year lifespan on the model I have, not going to mention the vendor so don't ask)


Video of the dripping fluid it was a steady stream when I first pulled the bolts:

https://www.youtube.com/watch?v=VKe-GVb4xK4

Do these dark trails mean the leak was at the top seals? These were wet so I'm guessing yes:
41358

Peeling black paint compliments of leaking fluid:
41359

Drips:
4136041361

Fuel tank wet with fluid:
4136241363

Peeling epoxy:
4136441365

[DavidProehl]

I found this post had good info on the POR-15 process: http://dmctalk.org/showthread.php?5199-Frame-Paint-Color-Comparison&p=77109&viewfull=1#post77109

[Spittybug]

I'm not sure why you are putting the vendor ahead of fellow owners in this case. 3 years is a terrible lifespan for those seals and you would be doing the community a service by letting us know whose they are. Likewise, the vendor should have the opportunity to stand behind their product and replace it. It is only through open dialogue that we as captive consumers of specialty car parts can hope to prevent total monopoly of supply.

[David T]

I'm not sure why you are putting the vendor ahead of fellow owners in this case. 3 years is a terrible lifespan for those seals and you would be doing the community a service by letting us know whose they are. Likewise, the vendor should have the opportunity to stand behind their product and replace it. It is only through open dialogue that we as captive consumers of specialty car parts can hope to prevent total monopoly of supply.

When you replaced the master you had to move the reservoir from the old one onto the rebuilt one. Is it possible you did something wrong or the reservoir is damaged in some way causing the leak? You need to make sure so the next one doesn't leak when you reuse the reservoir again. As for damage to the paint on the frame, you may need to remove the bottom plate under the fuel tank (and possibly the tank itself) to fix it all. If you did the actual replacement, and not the vendor, you may not be able to blame the vendor in this case. Sometimes it is not a faulty part but the way it is installed.

[DavidProehl]

I'm not sure why you are putting the vendor ahead of fellow owners in this case.
Because I've had great luck with this vendor and would continue to recommend them for other parts. I don't want to throw them under the bus in the event it wasn't actually their fault. I know several other owners using the same part for many years and have had 0 problems. I'll be calling them to understand if this is a known issue. You are right though, a 3 year lifespan is unbelievably short.


When you replaced the master you had to move the reservoir from the old one onto the rebuilt one. Is it possible you did something wrong or the reservoir is damaged in some way causing the leak? You need to make sure so the next one doesn't leak when you reuse the reservoir again. As for damage to the paint on the frame, you may need to remove the bottom plate under the fuel tank (and possibly the tank itself) to fix it all. If you did the actual replacement, and not the vendor, you may not be able to blame the vendor in this case. Sometimes it is not a faulty part but the way it is installed.

I pulled the bottom plate last night as well. It was peeling, I've since washed all the fluid off it. I was thinking the same thing about perhaps me accidentally damaging the reservoir, but if it was a faulty install or a broken reservoir I would have expected a leak long before 3 years. I do check my fluids on at least a quarterly basis (more typically monthly) so I would have noticed a leak had it been happening prior to the last couple months.

[PJ Grady Inc.]

I know from personal experience and feedback from owners that the China sourced brake and clutch cylinders are problematic when it comes to lifespan. We sell either Brass sleeved reconditioned or Italian sourced new brake cylinders for that reason. Non Chinese clutch hydraulic cylinders (both slave and master) are even harder to source and for that reason we generally advise to go with the brass sleeved reconditioned units which currently I believe only we offer. Although I'm aware of currently who sells what I do not want to be accused of slamming another vendor as that leads to escalating tensions and sources can and do change. My best advise is to ask your supplier the country of origin of their part you are considering as it is the consumers right to know.
Rob

[David T]

There is another possibility. If you installed the reservoir backwards it will go together but the reservoir is pushed because it is hitting the booster. That could cause a leak but I have no explanation for why it would be OK for 3 years before it leaked unless it was leaking slowly and only recently started leaking faster. I would carefully examine the nipples on the bottom of the reservoir for any cracks. You can clean it up with alcohol. Another possible cause is that when you put the reservoir on it didn't "pop" into the seals, instead sitting on top of them, being held in place by the pins. If you had to hold the reservoir down to get the pins in, that would mean the reservoir was not seated all the way into the seals in the master cylinder. Conversely, if the reservoir fell off when you pulled the pins and you didn't have to pry it off, that, again, would mean the reservoir was not seated fully into the seals. Just guessing here because you were the one who put it together and took it apart.

[DMC-81]

Hi David,

Sorry that this happened. One thing I was wondering as I read this is how cold did the car get while it was in winter storage? (i.e. I wonder if an extreme temperature made the seals shrink enough to let fluid by). Just a thought.

Also, I would recommend removing and repainting the brake booster. Mine looked like yours. I had good luck rebuilding it and repainting it with gloss black epoxy paint. Not sure if yours needs a rebuild, but " while you're in there..."

Here is a picture:

41385

Also, I found that Rustoleum Gloss Smoke Gray was a good match to the frame color.

Good luck.

[DavidProehl]

There is another possibility. If you installed the reservoir backwards it will go together but the reservoir is pushed because it is hitting the booster. That could cause a leak but I have no explanation for why it would be OK for 3 years before it leaked unless it was leaking slowly and only recently started leaking faster. I would carefully examine the nipples on the bottom of the reservoir for any cracks. You can clean it up with alcohol. Another possible cause is that when you put the reservoir on it didn't "pop" into the seals, instead sitting on top of them, being held in place by the pins. If you had to hold the reservoir down to get the pins in, that would mean the reservoir was not seated all the way into the seals in the master cylinder. Conversely, if the reservoir fell off when you pulled the pins and you didn't have to pry it off, that, again, would mean the reservoir was not seated fully into the seals. Just guessing here because you were the one who put it together and took it apart.

Thanks for the additional idea. Here is a picture of it while it was still installed:
41386

You can see the logo of the reservoir was towards the front of the car. Not sure if that is the proper orientation or not, but given that the Max/Min is facing the direction that I'd be filling it from I'm guessing it is correct.

It was definitely fully seated as I had to pry it off, but that doesn't mean the seal was good on the nipples, I think the leak clearly indicates it wasn't. I also don't see any damage on the nipples. I'm not ruling out a bad installation, but I did have a friend of mine who is a DeLorean owner & professional mechanic (vwdmc16 here on dmctalk) help me install it so I'm skeptical poor installation was the problem.


Hi David,

Sorry that this happened. One thing I was wondering as I read this is how cold did the car get while it was in winter storage? (i.e. I wonder if an extreme temperature made the seals shrink enough to let fluid by). Just a thought.

Also, I would recommend removing and repainting the brake booster. Mine looked like yours. I had good luck rebuilding it and repainting it with gloss black epoxy paint. Not sure if yours needs a rebuild, but " while you're in there..."

Here is a picture:

41385

Also, I found that Rustoleum Gloss Smoke Gray was a good match to the frame color.

Good luck.

Repainting the booster is a good idea. I certainly don't want it to rust out either. And to think it used to look so nice :(

[David T]

If the reservoir was not touching the booster, and from the picture it was not, then it was oriented correctly. Sine you say you had to pry it off we have to assume it was fully inserted into the seals. Since you also say the reservoir nipples appear undamaged the only conclusion we can come to is that the seals failed. Maybe all that is necessary is to replace the two reservoir seals, do some repaint, and you are good to go again!

[Ryan S.]

I'm not sure why you are putting the vendor ahead of fellow owners in this case. 3 years is a terrible lifespan for those seals and you would be doing the community a service by letting us know whose they are. Likewise, the vendor should have the opportunity to stand behind their product and replace it. It is only through open dialogue that we as captive consumers of specialty car parts can hope to prevent total monopoly of supply.

What? :jawdrop: I thought that 3 years was the average life span for Delorean parts. If I can get 5 years, I would be super happy. But for my Lexus, I expect 20+ years.

[DavidProehl]

What? :jawdrop: I thought that 3 years was the average life span for Delorean parts. If I can get 5 years, I would be super happy. But for my Lexus, I expect 20+ years.

Yeah, you have had the absolute worst luck. I think you or your car may be cursed. Compared to what you have had to deal with I guess I shouldn't complain!

[content22207_2]

Saab xRef from O'Reilly has a lifetime warranty: http://www.oreillyauto.com/site/c/detail/OBH3/112329/01292.oap?year=1981&make=Saab&model=900&vi=1265307&ck=Search_brake+master+cylinder_1265307_-1

Unit is proportioned 50/50, but quite a few owners are running one without incident.

eBay and Amazon also are full of them, sans lifetime warranty of course. You can get one with a new reservoir already attached.

Reservoir seals on eBay: http://www.ebay.com/itm/1987-1988-1989-Classic-Saab-900-ATE-Brake-Master-Cylinder-Reservoir-Rubber-Seals-/381587367661?fits=Make%3ASaab|Model%3A900&hash=item58d86126ed:g:ybkAAOSwQItT7db9&vxp=mtr

Bill Robertson
#5939

[DavidProehl]

Saab xRef from O'Reilly has a lifetime warranty: http://www.oreillyauto.com/site/c/detail/OBH3/112329/01292.oap?year=1981&make=Saab&model=900&vi=1265307&ck=Search_brake+master+cylinder_1265307_-1

Unit is proportioned 50/50, but quite a few owners are running one without incident.

eBay and Amazon also are full of them, sans lifetime warranty of course. You can get one with a new reservoir already attached.

Reservoir seals on eBay: http://www.ebay.com/itm/1987-1988-1989-Classic-Saab-900-ATE-Brake-Master-Cylinder-Reservoir-Rubber-Seals-/381587367661?fits=Make%3ASaab|Model%3A900&hash=item58d86126ed:g:ybkAAOSwQItT7db9&vxp=mtr

Bill Robertson
#5939

Thanks for the tip on the O'Reilly units. Didn't realize my local parts store had an option.

[content22207_2]

Local parts house may not have a free replacement if/when time comes. Autozone used to sell Saab brake masters with lifetime warranty as well, but no longer stocks them. Competition in the parts business is fierce so they drop parts that don't sell enough to be profitable.

xRefs will be available on eBay far into the future (don't forget to search British eBay: www.ebay.co.uk).

As stated, the Saab unit is proportioned 50/50. I spoke with an owner at the DMCMW open house who's running one no problem.

Bill Robertson
#5939

[cpistocco]

Has anyone tried silicone brake fluid in their D? Does not draw moisture. Brake components last much longer...

[David T]

Has anyone tried silicone brake fluid in their D? Does not draw moisture. Brake components last much longer...

Although silicone brake fluid, aka DOT 5, does not absorb moisture it is not meant for our brake system for 2 reasons. Just because of that fact, that it will not absorb moisture, any moisture that does get into the system will lay there in a bubble and rot the insides. The other reason is you cannot get ALL of the air out of the fluid so it is partially compressible. That means you never get a firm pedal. Stick with DOT 4 and change it every 2 years.

[DMCMW Dave]

I've seen a couple cars with silicone brake fluid, not impressed. The rubber stuff fails at about the same rate, and parts can rust just as bad as moisture still gets in there. The ONLY advantage is that leaks won't mess up the epoxy. It's not good in clutch systems as it is slightly more compressible, as David mentioned harder to get the bubbles out, and this is more critical in a clutch than in the brake systems. Slightly squishy brakes are just squishy brakes, but a clutch that doesn't disengage all the way will damage the trans.

[cpistocco]

I have used it in some of my other cars, and I swear by it. Yes....pedal is a bit squishier....but no degradation to metal. My calipers on my 74 corvette would constantly pit and leak. I honed them and switched to silicone...never another problem. :)

[David T]

I have used it in some of my other cars, and I swear by it. Yes....pedal is a bit squishier....but no degradation to metal. My calipers on my 74 corvette would constantly pit and leak. I honed them and switched to silicone...never another problem. :)

On many other old cars there is not enough pedal travel for squishy brakes. Before you can lock up the brakes the pedal is to the floor. Not good by any measure. The main reason racers use DOT 5 is for the very high boiling point. If you want long-lasting brake parts just get the cylinders sleeved or change the fluid every 2 years.

[DavidProehl]

My brake booster has been re-painted:
4150341504

The directions on the can said I needed to wait a week between coats, so I wasn't able to reinstall until today. Also replaced the original vacuum hose while I was in there.

Also prepped the cover plate for POR-15 (sanding, degreasing, metal prep):
4150541506

I have put a couple coats of POR-15 on (no pictures yet) and will be using rustoleum smoke gray as a top coat. Replacement master cylinder is on order, should be arriving in the next few days. With any luck I'll have a drivable car again next weekend!

[Ryan S.]

Good work David. We missed you at the Picnic day.

[DavidProehl]

Good work David. We missed you at the Picnic day.
Thanks Ryan, the pictures looked great. I wish I could have been there!

Quick update on progress.

Cover plate with POR-15:
4161341614

Cover plate with Rustoleum Smoke Gray topcoat:
4161541616

Re-painted brake booster and new master cylinder now installed:
41617

Next up, the joys of bleeding the brakes...I hate brake bleeding so much. Easily the part of this job I hate the most.

[Ryan S.]

Next up, the joys of bleeding the brakes...I hate brake bleeding so much. Easily the part of this job I hate the most.

I just did mine last night because I had to replace my leaky front ss lines. I used motive power bleeder and it wasn't too difficult. I bought this and made catching fluid less messy.
http://www.amazon.com/Genesis-Cable-Bleeder-Bottle/dp/B000W7F2GI?ie=UTF8&psc=1&redirect=true&ref_=oh_aui_detailpage_o06_s00

I also bought a case of castrol brake fluids from Amazon. Their price was pretty good.
http://www.amazon.com/Castrol-12509-12PK-DOT-4-Brake-Fluid/dp/B00B9XDJQO?ie=UTF8&psc=1&redirect=true&ref_=oh_aui_detailpage_o08_s00

[Chris 16409]

I really like my Motive power bleeder. It makes bleeding the breaks a breeze. Castrol DOT 4 is getting harder for me to find locally. Orchard Supply Hardware used to carry it, but they have drastically reduced their automotive section. I was able to get a few bottles when they had it on close out.

[DMC-81]

Thanks Ryan, the pictures looked great. I wish I could have been there!

Quick update on progress.

Cover plate with POR-15:
4161341614

Cover plate with Rustoleum Smoke Gray topcoat:
4161541616

Re-painted brake booster and new master cylinder now installed:
41617

Next up, the joys of bleeding the brakes...I hate brake bleeding so much. Easily the part of this job I hate the most.

Looks great David!

[DavidProehl]

I just did mine last night because I had to replace my leaky front ss lines. I used motive power bleeder and it wasn't too difficult. I bought this and made catching fluid less messy.
http://www.amazon.com/Genesis-Cable-Bleeder-Bottle/dp/B000W7F2GI?ie=UTF8&psc=1&redirect=true&ref_=oh_aui_detailpage_o06_s00

I also bought a case of castrol brake fluids from Amazon. Their price was pretty good.
http://www.amazon.com/Castrol-12509-12PK-DOT-4-Brake-Fluid/dp/B00B9XDJQO?ie=UTF8&psc=1&redirect=true&ref_=oh_aui_detailpage_o08_s00

I bought that same case of brake fluid off Amazon a couple weeks ago. Can't find the stuff locally at all.


I really like my Motive power bleeder. It makes bleeding the breaks a breeze. Castrol DOT 4 is getting harder for me to find locally. Orchard Supply Hardware used to carry it, but they have drastically reduced their automotive section. I was able to get a few bottles when they had it on close out.

That is a good idea about the power bleeder. Have you tried a vacuum bleeder like this (http://www.amazon.com/HFS-Brake-Bleeder-Vacuum-Tuner/dp/B00NP60URE?ie=UTF8&psc=1&redirect=true&ref_=oh_aui_detailpage_o00_s00)? The difference being the power bleeder pressurizes to push it through while the vacuum bleeder pulls it through. Pros/cons of either approach?


Looks great David!

Thanks!

[DavidProehl]

Big thanks to Alan for coming over tonight to help me wrap up the brake bleeding process. The job is officially done!

Here is a photo of my re-installed gas tank plate:
41712

[Ryan S.]

Very Clean!!! Nice.

[Alan]

Big thanks to Alan for coming over tonight to help me wrap up the brake bleeding process. The job is officially done!

It was fun. Always a good time hanging with another owner.

[ILM1010]

looks great guys! Dave why are you so darn smart at everything, I don't even know where the brake master cylinder is. By the way, I'm only 10 min away from you in Albertville. Ive had the Delorean out quite a bit this year, running good so far.

[DavidProehl]

looks great guys! Dave why are you so darn smart at everything, I don't even know where the brake master cylinder is. By the way, I'm only 10 min away from you in Albertville. Ive had the Delorean out quite a bit this year, running good so far.

Ha! Thanks. Everything I know I've learned from other owners, either here in MN, the NorCal club, or DMC Talk. Tech sessions are seriously the best way to learn how to do jobs on this car. That is 90% of where my confidence in working on various jobs has come from. Yay tech sessions! Speaking of which...Alan and I were talking about getting one going in May. Details to come!

[yianni]

My mc started to leak between seals and reservoir. Is this a mc failure or seal failure? The mc is two years old from DMCH with my original tank. Do I have an option here just to replace seals, and does anyone know a source for new ones? The only ones mentioned here are the Saab 900 mc seals. Do they even fit our masters? If any one has dealt with this issue can you please give me your thoughts. Thanks

[DavidProehl]

My mc started to leak between seals and reservoir. Is this a mc failure or seal failure? The mc is two years old from DMCH with my original tank. Do I have an option here just to replace seals, and does anyone know a source for new ones? The only ones mentioned here are the Saab 900 mc seals. Do they even fit our masters? If any one has dealt with this issue can you please give me your thoughts. Thanks

That sounds like exactly what I was dealing with: new(ish) leaking master cylinder at the reservoir seals. I think if you call any of the vendors they would have replacements for you. In my case I lost faith in the other seals on the master when those went out so I decided to replace the whole unit. If bad rubber is used in one place it is easy to assume similar type rubber is used elsewhere on the unit.

[Tillsy]

Guttered to say I have had exactly the same failure.

Last week I spent three nights doing an intense clean for a major South Australian historic cruise my DeLorean finally qualifies for - I had noticed a small pool under the car but obviously assumed it was just some water, but on the third night began wondering why it was still there.

Sure enough, golden amber goodness... and it's everywhere, the paint is like melted cheese. Going to be one hell of a fix up job - what utterly infuriates me is that I had already done this massive job 5 years ago when I discovered there had been a leak from a prior owner, so had removed the tank and done a massive clean-up at the time. Now I have to do it all over again.

The hard lines and joins were bone dry on the outside, but underneath the master cylinder was damp. Narrowed it down to coming from between the reservoir and master cylinder, so the seals have given way.

In my case I got 5 years out of a brand new master cylinder from DMC MidWest - but that's still shocking, those seals shouldn't just fail in that length of time. Not happy with what has happened and the amount of work it's going to take fixing it up, not to mention losing out on going on that historic cruise and my entrant fee. Has been a depressing few days taking a breather on this, starting the strip-down job today. Totally shattered at what has happened.

[David T]

If you don't flush the brake fluid every other year you can expect to see problems with the brake system. The fluid should not be a golden amber. It should be clear to slightly milky white. As it absorbs moisture from the air, it gets darker and darker. If it is leaking from the reservoir seals it is possible you did not mount the reservoir correctly or you damaged the seals installing it. It can also leak if you put the reservoir on in the wrong direction. It will fit but it hits the booster and doesn't seal right and leaks. You must remove any epoxy that has detached from the metal, clean well, and repaint. To do a proper job may require removing the fuel tank.

[Tillsy]

If you don't flush the brake fluid every other year you can expect to see problems with the brake system.
I completely redid the brake system 5 years ago - rebuild the callipers, new master cylinder, and new lines. Since then I have flushed the brake system every ***12*** months, the last time was ***9*** months ago.


The fluid should not be a golden amber.
Castro React Performance DOT4 looks clear to the eye but through light is a gorgeous golden amber, like looking at a tinted crystal or diamond. My brake fluid still looks exactly like it came straight out of the bottle. When it gets to 2+ years old it starts to head more a browny tint and then gets worse and worse. I flush mine every 12 months so it never looks anything like that, always a gorgeous slightly yellow tint.


If it is leaking from the reservoir seals it is possible you did not mount the reservoir correctly or you damaged the seals installing it. It can also leak if you put the reservoir on in the wrong direction.
You can't mount it backwards and fit properly or even see the fill line. The reservoir nipples simply slide into the seal.


You must remove any epoxy that has detached from the metal, clean well, and repaint. To do a proper job may require removing the fuel tank.
Yes as I said I mentioned I've done this job once before so I'm aware, and hence very unhappy, at having to do it all over again.

[Chris 16409]

Guttered to say I have had exactly the same failure.
The hard lines and joins were bone dry on the outside, but underneath the master cylinder was damp. Narrowed it down to coming from between the reservoir and master cylinder, so the seals have given way.

I have a friend that had bad reservoir seals out of the box. I think they just aren't that good of a seal. I believe he simply reused the seals from his original unit and never had another problem.

[David T]

Here in the US we use Castrol DOT 4 Synthetic Brake Fluid formerly known as GTLMA. Maybe the stuff you are using doesn't work well with the rubber. If you bench-bleed the master with the reservoir on backwards and then install it, it will fit but not right and the seals will leak because the reservoir is hitting the booster. Just guessing about that one but worth mentioning. Sine you say you flush every 12 months, old, bad fluid is probably not the problem. Incompatibility may be the problem.