Brake Master Cylinder Leaking

Joined
Jun 12, 2007
Messages
1,668
Location
FL
Hello,

I recently replaced the brake master cylinder (it was leaking from the rear near the firewall) on my 84 Rx7 with a brand new unit. Now, the new unit I replaced it with now looks like it is weeping brake fluid from the same area as the old one! I installed the new unit without bench bleeding (learned after the fact) but was still able to purge the air out of the lines. My question is, could not bench bleeding first damage the master cylinder? Or is this just bad luck? Either way I'll have to buy a new unit soon.
 
...or bad quality replacement parts. not sure of the situation w vintage Mazda parts availability, but it isn't exactly rare to hear of faulty new parts in the vintage British car world.

Was it new OEM? Was there a pool of fluid somewhere from the original cylinder that is seeping and looks like a leak? Maybe the hydraulic clutch master (if u have one) is also leaking... I've experienced all the above over the years.

Nice car BTW. I like the early RX7's, I remember riding in one my Parents test drove in 1982.....
 
...or bad quality replacement parts. not sure of the situation w vintage Mazda parts availability, but it isn't exactly rare to hear of faulty new parts in the vintage British car world.

Was it new OEM? Was there a pool of fluid somewhere from the original cylinder that is seeping and looks like a leak? Maybe the hydraulic clutch master (if u have one) is also leaking... I've experienced all the above over the years.

Nice car BTW. I like the early RX7's, I remember riding in one my Parents test drove in 1982.....

This is a new Beck / Arnley master cylinder from Rockauto. It was definitely the Brake master as the reservoir was nearly empty 😬 The clutch master cylinder (yes hydraulic) is fine. I thought a NEW part would have been fairly safe unlike questionable rebuilt parts. Surprisingly, the master cylinder was made in Taiwan, not China.

I've read multiple articles online about bench bleeding and they state that new master cylinders should come with a bench bleed kit, the Beck / Arnley did NOT.
 
Last edited:
Sometimes Beck is OEM, sometimes not... I will now generally only by OEM critical parts where available, w/ a carefully researched quality aftermarket part close second. I've been burned one too many times, last was a Defender rear brake cylinder. I was buying all of the rear brake parts from one supplier, but they only had the left in OEM, w R in their house brand. Installed, tested fine. Next morning there was a drop of fluid on the R backing plate. Replaced w/ OEM (well...the successor entity TRW).

Can you have your original rebuilt? Sleeved?
 
I tossed the Master cylinder that was leaking, I'm not sure if it was OEM... I think it may have been replaced once sometime before I owned the car which would be 15+ years ago. Looks like Mazdatrix has a Mazda OEM unit available $90 vs the $65 (ship incl) should have spent the extra few bucks on the OEM. Lesson learned.
 
Sorry about your bad experience but you're not alone. The quality of replacement parts is all over the spectrum these days. OEMs are pricing their stuff generally at nosebleed levels, a lot of competitors jump in to fill the price gap, lots of faulty stuff. There was an editorial in Hot Rod magazine about this several months ago.
 
Back
Top