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:

1. Rinse out entire area with soapy water to clean out leaked fluid
2. Use some type of epoxy/pait stripper (recommendations?) to clean affected areas.
3. Re-paint with POR-15
4. Spray over POR-15 with rustoleum that matches existing epoxy
5. Reinstall cover plate
6. 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:


Do these dark trails mean the leak was at the top seals? These were wet so I'm guessing yes:
20160406_173809.jpg

Peeling black paint compliments of leaking fluid:
20160406_174034.jpg

Drips:
20160406_194418.jpg20160406_194441.jpg

Fuel tank wet with fluid:
20160406_200054.jpg20160406_200154.jpg

Peeling epoxy:
20160406_200550.jpg20160406_201607.jpg

[DavidProehl]

I found this post had good info on the POR-15 process: http://dmctalk.org/showthread.php?51...ll=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:

image.jpg

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:
20160406_171822.jpg

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:

image.jpg

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!