# Difficulty bleeding brakes



## nibor17 (Dec 15, 2014)

Hello everyone,

First, I'm a newbie at working on cars, but part of the reason I bought my 300 was to learn, which I have done a lot of! But still, forgive me for being ignorant!

So, after replacing the rear subframe bushings in my 84 Turbo, I have not been able to successfully bleed the brakes. The job required detaching the soft rear brake lines at the rear crossmember. I had hoped that because the rear of the car was raised about 18 inches into the air, all I would have to do was to bleed the rear brakes of air and top up the fluid. 

Before bleeding, pedal was soft and wouldn't get hard with pumping, and there was a fairly quiet wheezing sound coming from (I think) the master cylinder. Could only be heard with hood open and window rolled down. Blamed it all on the massive amount of air in the lines. So, I bled the rear brakes. The pedal was slightly firmer and would build up some firmness, but it slowly depressed under pressure if I didn't keep pumping it. 

So I bled all four brakes, and the pedal was slightly firmer after pumping, but still falls under pressure. Went around and bleed all four three more times- no change. Now, it could be that there is still a lot of air in the rear lines, but the bubbles coming out of the bleeder valves are the small, uniform type that I'd expect to see leaking in from the open valve itself, not from the system. Maybe there is sill air in it, but I have gone through about 70 oz of brake fluid. The front brakes have no bubbles at all, but the valves are larger and provide a better seal on my tubing. There are no fluid leaks that I can find anywhere. I initially had my brother pump the brakes while I opened and closed the valves, but I am now using a hand vacuum system. 

I tried turning the car on, and the pedal has almost no pressure at all, goes all the way to the floor.

I also still have the wheezing sound coming from the master cylinder. Starting to think it just might be bad. Also, not sure if this might have causes any issues, but while the rear brake lines were off I turned on the car to test something. Could turning on the car with the brake lines open damage anything?

I also still have the wheezing sound coming from the master cylinder. Starting to think it just might be bad. Also, not sure if this might have causes any issues, but while the rear brake lines were off I turned on the car to test something. Could turning on the car with the brake lines open damage anything?

Anybody got any ideas? Do I just need to keep bleeding it? Should I try bleeding the master cylinder? I'm a noob- so I have no idea how to do that! ;-)

I'm pretty much at my wits end with this!!! Thanks for any advice you can give.


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## lilsind (Feb 23, 2015)

replace master cylinder bleed brakes rear passenger side, then rear driver side, passenger front, driver front. Bleed each one 2 or 3 times are done. Fill fluid every time you bleed each one. Go to XenonZcar.com Z31 Factory Service Manuals an download free, it tells you just about everything about Z.


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## smj999smj (Jan 1, 2006)

Actually, for 84-88 300ZX, the bleeding procedure is: left rear, right rear, right front, left front. (left=driver's side; right=passenger side)

http://www.autozone.com/repairinfo/repairguide/repairGuideContent.jsp?pageId=0900c1528007202c


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## ralph50 (Feb 24, 2015)

If the brake fluid runs low while bleeding air could get in the MC. I would bleed the MC. Bench bleeding is best and take it from there.

Always start bleeding from the furthest tire and work your way to the closest.

Use a clear vinyl hose to bleed so you can see the air bubbles.

Bleed till you no longer see any air bubbles making sure the fluid does not get low in the MC reservoir.

I have used the one man bleeding kit. Like $7 and it works well.


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