low brake fluid issues

[804zxkid]

Hey guys, im having a problem keeping brake fluid. About 2 weeks ago my brake light on my dash came on so I checked my brake fluid level. Sure enough it was just under the "min" marking so I filled it up right below the max marking. The brake light still didn't turn off but i didn't think much of it. Today I checked the level again and it was completely empty! the brakes felt fine and nothing felt out of place. I filled it up again to the max marking, this time the brake light on the dash turned off. I took it for a drive and everything felt the same. I checked underneath for any leaks and all I found was a few drips coming off the resonators, I doubt that has anything to do with it. I looked around the brake master cylinder and underneath, it looks dirty and a little moist but not fresh, like it might have leaked in the past. I checked all my calipers and they are dry. I couldnt get any pics because its getting dark much earlier now with the new time change but ill get some tomorrow. Feel free to let me know what it might sound like.

PS: within the two weeks that i lost all my brake fluid i only drove about 150 miles.

[OutToWinPAHC]

Check the carpet and padding near the pedal, scary your gonna want to get a friend to pump the brakes over and over while your under it.

[804zxkid]

Just checked the carpet, its dry. Do you mean have someone pump the pedal whileim underneath the dash?

[t.mcginley.jr]

Sounds like a slow leak out of one of the lines. Sometimes it can leak where the master cylinder meets the brake booster, but the bottom of the booster and around underneath that area would be moist/wet. If it took 2 weeks to drain then it must be a pretty slow leak. You'll just have to trace the lines from front to back

[nissanfreak12]

Check by the ABS pump by the rear shock tower, passenger side.

[804zxkid]

Hey guys I jacked my car up early this morning and found some things. I looked underneath the car again and saw resh fluid on the ground directly were the mbc goes. I checked the left front caliper and no leak. I saw the part of the chassis directly under the mbc was coated in brake fluid,there was also some fluid on the brake booster. Which one is most likely leaking? I got pics but I can't figure out how to upload them

[nissanfreak12]

Master cylinder, all the brake booster does is assist you in pressing the master cylinder, it hold zero fluid.

[804zxkid]

Its definitely leaking out there, and faster too. I will replace it this weekend. Are these pretty easy to replace? Can't find a write up anywhere.

[itsa300zx]

Very easy to replace the MBC, just make dure to use a flare nut wrench for the steel brake lines. Unbolt the two nuts on the booster, disconnect the connector, swap BMC, and bleed the entire system.

[804zxkid]

Alright, I see a lot of remanufactured bmcs online, they don't have the reservoir. Would I be able to swap mine over or could that be the part that's leaking?

[itsa300zx]

I know they sell kits/o rings with the reservoir. My money is on the main cylinder seals. The reservoir seal to MC should not see any pressure. If I were you, just buy the entire complete unit. Be sure you look on yours for the manufacture, and buy the same. I believe in early 90 models, they had 2 different sized MC's.

[804zxkid]

On the z1 website it says the bore sizes are interchangable. I'm gonna go pick this up http://m.oreillyauto.com/mt/www.oreilly ... t_redirect should work right?

[itsa300zx]

Yeah, that will work.
Maybe mine is special, production date 5/89. When I ordered mine last year, the dealer asked me what was the manufacture (Nabco or Tokico)?? (15/16 or 1")??

[t.mcginley.jr]

Should be interchangeable, MC's are all basically the same no special technology there, some are just better quality than others. Not sure on the Z but most cars use a gasket between the MC and the booster, if it requires one then definitely replace that too.

[804zxkid]

I ended up getting the remanufactured. The guy told me that's all they carried now. Should have it in Thursday. Hopefully now I can go places without leaking everywhere! Now lets see how this election goes!

[nissanfreak12]

Make sure you bench bleed the MBC before installing. Bench bleeding while in the car is no fun by yourself.

[t.mcginley.jr]

Make sure you bench bleed the MBC before installing. Bench bleeding while in the car is no fun by yourself.

+++++++++1 (super important lol)

[804zxkid]

What is bench bleeding? And the fluid probably isn't gonna be leaking out the brake booster right?

[t.mcginley.jr]

When you get a new MC you need to get all the air out of the cylinder by bench bleeding it. Basically you fill the reservoir up, run rubber hoses from where the brake lines thread in to the reservoir and pump it with a big screw driver. Read this:

http://www.nicoclub.com/archives/diy-bm ... r-kit.html

They sell universal bench bleed kits at any parts store

[804zxkid]

Update, just finished getting the mbc in and test drove it and no more leaks! Got all the old grime off and its alot cleaner! They were both the same bore size (1/16). Thanks for the help guys.

[nissanfreak12]

Glad you got it fixed!

[t.mcginley.jr]

Awesome!