Testing/Inspecting Brake Master Cylinder

I have a question regarding the master brake cylinder, on the 1980 Honda Civic I'm attempting to restore. When I acquired this vehicle, the brakes
were totally non-functional, and depressing the brake pedal produced a strange groaning noise from the master cylinder area. I later discovered that one wheel cylinder was missing and the fluid had been allowed to drain from that line. The other three lines were still connected and still contained fluid. However, the fluid reservoir was empty - but I don't know for how long. If it was empty to start with, it probably has been for the last several years the car has been sitting. Otherwise it's only been a couple of months. I'm told that the seals on the piston will dry up and crack in the absense of brake fluid, necessitating replacement. But should I automatically assume my cylinder needs replacing, or is there any way to inspect it or perhaps test it (while driving around in the yard, for example). I'd rather not replace it unless I had to. I am however replacing all of the brake lines, and the rear wheel cylinders, just to avoid problems down the road. Thanks for any advice.
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Chris F. wrote:

I've had 2 master cylinders fail on me. My bet is that you'll have no qualms about replacing it when that one fails on you. How expensive is a Honda MC? I remember the replacements for my cars to be around $60.
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On Fri, 30 Oct 2009 16:06:16 -0700, Chris F. wrote:

What happened on my truck was that one of the wheel cylinders went bad and all the fluid disappeared - when it did so, years of accumulated crap in the resevoir was drawn into the master cylinder. Some of the crap stuck itself between the piston seals and bore of the master cylinder, which meant it started leaking.
I stripped the whole lot down, cleaned, inspected the bore for corrosion, checked the seals etc. and reassembled, and it's been fine since. I disconnected the brake lines and pumped a whole bunch of fluid through them to flush them, then stripped + cleaned + checked all the wheel cylinders (most of them were full of crap, too).
This was with a servo with no vacuum assist (too old) whereas I'm sure yours is - although I don't suspect they're that much more complicated to pull apart.
cheers
Jules
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I figured as much. I can get an aftermarket MC on Ebay for about $75 shipped, so I guess that's what I'll do. You're right, it's not worth taking chances with.

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I'd recommend you buy from NAPA or other local supplier. That way your warranty will actually be worth something if things should go wrong, which is common with aftermarket parts.
--
Tegger


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Do you have any experience with Centric brake products? I have to order a brake spring/hardware kit from one of their distributors, and I could order an MC from the same place while I'm at it.


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No experience whatsoever with "Centric". But if they're anything like any other aftermarket suppliers, their quality for Honda parts will be hit-and-miss.
You can go ahead and order from them, but keep your receipt until the warranty is up. Chances are good you'll be making use of that warranty.
I happen to be running an aftermarket-reman MC bought from a local NAPA in 2005. It's still working just fine. It was $70 versus $350 for new OEM Honda (Nissin). I consider myself lucky.
--
Tegger


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Chris, these are /brakes/ you're talking about. Brakes are what keep you from smashing into things that will damage your finely-restored ride and may perhaps even make you not-alive anymore.
A reman aftermarket MC from your local NAPA is about $80-100. Do **NOT** cheap out on this part. Deliver a few more pizzas or newspapers, or sponge off the relatives to raise the money. Just don't try to make do with the existing MC.
--
Tegger


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On Sat, 31 Oct 2009 01:20:35 +0000, Tegger wrote:

Yes, don't think I mentioned that in my post, but hopefully it's obvious :-)
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But should I automatically assume

Absolutely, I do it all the time. Take the master cylinder apart and pry the rubber pistons off. Using a sharp razor blade, carefully cut them all in half and check for dryness inside. Its the only safe sure way to know for certain. I do the same with carb floats...
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That post, after I see it online, came off trollish, snarky and condescending. I apologize.
Ben
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