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Index > @ the Pickup Bed (General Topics) > Thread: Brake Master reservoir leak
Thread: Brake Master reservoir leak
mazdarx605


Redlining
Posts: 314
posted February 08, 2012 08:23 PM

Brake Master reservoir leak

Hey guys,

Winter has been pretty easy here in New England and as such I was able to use my truck for a dump run a couple of weeks ago. On the trip the clutch hydraulics let go ( I limped it home). I bought a new clutch master, and slave for it online. Well this past Friday I went out to the garage to install it, and noticed the brake master was wet around the rear portion of the reservoir. I pulled the cap off,and sure enough that portion of the reservior was almost completely empty. I tried figuring out where it was leaking,and found it to be seeping out around the rubber plug that the reservior pushes into.

Now last spring I replaced the master cylinder so the rubber should be good. When I did this the new MC didn't come with a new reservior so I had to reuse the one from the factory. The reservior is not cracked from what I can see, but it is still leaking around under the rubber. Any ideas as to why? Any ideas on how to fix it? Does anyone have a source for a better MC that maybe comes with a new reservoir? Anyway to seal it up so it doesn't leak anymore? I pulled the rubber out of the MC to have a look at it,and it looks to be fine. The mating surfaces also look to be fine as well. Any help would be much appreciated. FYi I think the reservoir was maybe mounted so that there was two screws through a tab on the front or back to hold it down, but the new MC didn't have provisions for that.

Chris in Massachusetts

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hunter


Hauling
Posts: 178
posted February 09, 2012 12:39 AM

Reservoir leak

IMHO the rubber seals should be replaced, at least the rear one that is leaking. The rubber seals are in short supply as is the 'tank kit'. Might be best to start over with a new Master Cylinder that comes with the tank....
unfortunately.
I wonder if someone like Cardone can supply the seals.
try them ... 215-912-3000

       
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Brad


Rotorhead
Posts: 1671
posted February 09, 2012 11:56 AM

The reservoir from a 79 or 80 rx7 can be used. They're cheap. Pound it on with a wooden dowel placed in the reservoir. They're a bitch to get in right. Also used an orange deadblow hammer.
____________
-brad-
74 REPU Lawn Green
81 Rx-7 racecar. 12a J-
Bridge

       
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spokanerxdude


Hauling
Less cubes... More balls
Posts: 181
posted February 09, 2012 06:59 PM

Vaseline works extremly well putting the reservoir on. ya ya I know all the vaseline jokes. It works!
____________
Allen Ervin, spokanerxdude@yahoo.com
509-998-9024

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MAZDAMARK


Hauling
Posts: 139
posted February 15, 2012 04:40 PM

I thought petroleum jelly caused rubber seals to swell and crack... I had used brake caliper grease as it's safer for rubber.
____________
94 RX7
89 RX7 GTUs
85 GSLSE
88 323 GTX
1975 REPU

       
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Brad


Rotorhead
Posts: 1671
posted February 16, 2012 11:42 AM

Used brake fluid. Seems slippery enough.

       
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kansei


Redlining
Wankelized
Posts: 423
posted February 24, 2012 04:17 AM
Edited By: kansei on 24 Feb 2012 04:18

Chris,

Just a guess, but it probably has to do with the original reservoir's age. A few years ago, I was reading up on plastic reservoirs, looking into reproducing them before a few of the manufacturers and rebuilders started offering plentiful, inexpensive choices on hydraulic masters with new reservoirs for some of the cars and trucks. I recall reading that some of the older plastics, primarily those produced before the late 1980s, especially the translucent and semi-translucent ones used solvents to help them cure that would sometimes act like paints- they were still 'technically' curing months or years later. As they continued to cure, and from use and underhood heat, the plastics would shrink some over time. I know it is a long shot, but it *might* be at least some of your issue, that is if the reservoir ports on the new master are the same size as the original. I'm no chemist, nor do I really understand any intricacies of plastics manufacturing, I just recall that I hit a bit of a wall when I discovered it would be much easier to cast the reservoirs in a non-translucent manner than to do it correctly and inexpensively enough to make the project feasible. With the inexpensive new stuff, thankfully I never had to revive the project. The last time I tried to order more tank kits a couple years ago, it came back NLA, even when we tried to order them directly from Japan through Irvine. Maybe the number is good again, not sure. Just put the new one on and call it good.

Neal.

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mazdarx605


Redlining
Posts: 314
posted February 24, 2012 04:53 AM

Allright, so here is the problem I am still having. The new one I bought is still leaking. I had a brainstorm about the factory one that I pulled off when installing the one that is leaking. I don't think it was actually bad when I pulled it off, beacuse after I installed the new one the brakes still didn't feel great. Turns out the rear wheel cylinders were leaking badly, and were causing the brakes to not feel so great.


Well because I am a pack-rat I didn't throw away the old factory MC. I contacted Cardone in Philadelphia via Rock-Auto about rebuilding the factory MC even though I am not sure it is bad (I just thoought it would be smart). Well I mailed it out to them last week, and was really excited to see a package for me on the kitchen table yesterday afternoon, only to find it was the same old MC with a note saying they couldn't rebuild it. I contacted them to ask why,and they said they didn't have the parts. Well that was a solid $10+ in shipping to have them tell me they couldn't do it!!!!

Now I am stuck with the one that is on the truck,and leaking in a really weird way,and my factory one that I am half tempted to try out again, but it may be bad now that it has dried out from not being used. Holy run on sentence Batman!!!!!! The thing is where the new one has the rubber for the reservior it is just a hole that goes all the way down to the piston area it seems, but the factory one has a rounded bottom to it with a small hole at the the bottom where the fluid is allowed to enter the piston area. Maybe that is where I am running into troubles. This is very frustrating as I use this truck a lot in the nice weather, but without a trustable MC it is pretty useless to me. Can anyone help?

Chris

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