Vanishing brake fluid after sitting for six months?
 

I pulled my GXL out of storage today and noticed that the brake fluid was just a little above the MIN line on the resevoir. It was definatly full when I put it in storage and aside from a little spot of unknown liquid on my dirty ass garage floor directly under the fuel filter I have no idea where it went.

I check the cabin, all the calipers and lines in between and not a spot of anything I could identify as brake fluid. I filled the resivoir back up, took it for a slow test drive and the brakes are just fine. I did some hard braking and was able to lock the wheels up w/o a problem and after parking again couldn't find any leaks. The resevoir was full and I'm confused as all hell.

Brake fluid doesn't evaporate at normal temperatures, does it? I thought it took pretty high temperatures to vaporize it.

When was the last time you checked the level before you put the car up? I'm sure you realize that as the pads wear the fluid in the MC reservoir will drop. So, if it had been a long time since you checked the level, you may not have a leak at all. Keep a check on the fluid level and if it doesn't drop drastically and the pedal feel is firm, you should be OK.

One place you may not have checked, though, is at the back of the MC where it bolts to the booster. If you see fluid running down the face of the booster below the MC, you have a leak out the back of the MC and it would have to be rebuilt or replaced.

I checked it when storing and it was full, so I'm sure it's not pad wear.

I'll check behind the MC by the booster though, thanks for the suggestions. :)

If it's leaking there, the brake booster is most likely ruined too since it eats away at the little rubber seal on the booster when it leaks there, so make sure you check that too.

A place where the fluid goes sometimes is down the inside of the firewall. Pull up your rug behind your pedals, to see if there is any fluid there.

:D that was the first place I checked. I figured it would be just my luck to find a puddle of brake fluid under my carpet. :)

Where's the best place to snag a master cylinder and possibly brake booster from? Are the boosters pretty simple to rebuild (It's just a cylinder with some o-rings, right?) or is it better just to grab a new one?

I'm planning on doing alot of Solo II driving this year and definatly doing a few laps at Road America for the Midwest Rotary Revolution in the fall so I should probably look into replacing it anyways.

I'm having a similar problem, my 87 has been sitting for about 6 months, and my reserviour has sprung a slow leak. I filled it back up, got brake pressure back, and it will leak back out in about 4 weeks.

So I guess I have the same question... replace the master cylinder, or are there bushings or washers under the reserviour that can be replaced?

I have attached a pic.

By the way, uRizen, Mazdatrix has Master Cylinders for $135. I don't know if that's good.

man in the last week mine leaked as well. and it happened while i wasnt even driving it too!

looks exactly like the pic that was posted , you can see the brake fluid around the base of the resevoir.... what is the fix for this?

please help : )

replacing the brake master cylinder :(

that's what i did, anyways
i just went to pepboys and they ordered a remanufactured brake master cylinder for 100, and gave a 40 dollar core refund
and it came with the reservoir attached

then i checked o'reillys and they had it for 50 dollars with a 10 dollar core refund :uh:

looks like im up for a new master cylinder....

thanks!

Me too, I guess

haha were both up for some $$! gotta love dem rotaries ..lol

Actually, mine looked like kazin's at one point. The fluid was leaking out of the rubber, um, 'o-ring' I guess you can call it, that holds the resevoir to the MC. I just replaced the MC, and I haven't had any problems. I suggest not to rebuild it, but just to get another one. The bore in the cylinder my have notches in it, and if you don't notice them and just replace the o-rings and such, you will still have more problems.

NOPI sells the Tokico at a reasonable price. Sometimes you can find them on sale...

http://www.nopionline.com/nopistore/...A%20RX7%201987

I had problems with brake fluid slowly draining out during the winter as well. Last winter it wasn't too bad, so I pretty much ignored it & just checked the fluid every so often. This winter, it was much worse. I replaced the master cylinder & brake booster, and it's been fine. Stops better, too.

It seems that a lot of brake fluid can leak out the back of the master cylinder and into the booster without dripping much on the ground - so no visible drips just means it's pooling somewhere.

-=Russ=-

Hey , am I allowed to post over here ... with you NEW car guys - ha - compared to my 84...

Anyhoo, bored at work and having had MC leaks this past winter (would spill onto floor when temps dropped below freeze point) , i must add my story.

I ordered a rebuild kit, had the cylinder honed VERY LIGHTLY, and discovered the piston was TOO big. SO, the old parts LOOKED fine, so I put the old parts back in, and it works fine. No leaks for months now.

There was a minor deformation in the bore where the rearmost seal sits. That apparently was the leak spot. The honing cleaned that up nicely. A machinist did it - I knew he would have "the touch" since I don'y hone too often. Cost of hone $10. Cost of honing tool: $17 - and it looked a bit larger than the tool the machinist used. The honing tool he used had 2 stones and very light spring pressure.

SO it is possible to repair the leak without replacing the cylinder. I just dont trust all the remanufactured stuff all the time.