B.C.

Hi all:

Am in the process of changing my brake fluid and had a few questions:

1) I inadvertently let the reservoir go dry while flushing the brakes. Will I get all the air out of the master cylinder simply by bleeding the brakes or will the master cylinder need to be bled somehow?

2) When filling the reservoir, can the lid be screwed back on and allow for fluid to be bled (to try and keep moisture out as much as possible) or should the cap be left off in order to allow air to displace the fluid that is bled out. I noticed that the fluid seems to bleed just fine with the cap on and was wondering how that air is displaced.

3) Left side means as in when sitting in the car, ie left = driver, correct??

Thanks

Daniel B. Martin

Bleeding the brakes eliminates air in every part of the hydraulic system including the master cylinder.

I prefer to let the reservoir cap sit lightly (not "clicked" closed) on the reservoir fill port. That prevents dirt from falling in, yet makes it easy to replenish the reservoir during the bleeding process.

Correct.

Eric L.

You will just have to bleed the system a little more than normal to get all the air out if you let the reservoir go dry. Hope you have a big bottle of brake fluid handy. I find that for my Maxima, a normal flush uses up nearly 32oz of fluid.

njmaxseltd

iTrader: (19)

You can get a hand held vaccum pump to help you bleed the brakes. They come with a bottle for collecting the fluid. Makes the job easy if your doing it by yourself. Most automotive shops sell them for around 20 bucks. Well worth it.

B.C.

Thanks everyone for your help.

Does anyone want to take a stab at why the fluid can be discharged (two person method of bleeding) even with the reservoir cap on? How can air get into the reservoir to displace the fluid discharged?

Daniel B. Martin

The cap on the brake fluid reservoir is vented. It is a pressure/vacuum release valve comparable to a radiator fill cap. It isn't obvious because the whole thing is made of plastic and neoprene rubber.

B.C.

One final question on brake fluid changes using the "two man method". My 1995 FSM says that after fully depressing the brake pedal, the bleeder valve should be opened to allow escape of air. Is there any problem with allowing the pedal to fully hit the floor of the car during this process before closing the bleeder valve again? The FSM says nothing about how far down the pedal should be depressed while the bleeder valve is actually open. I would hope there are some "stops" built into the booster, etc. to avoid straining any components if the pedal hits the floor with any force. Any thoughts on this?

Thanks

Daniel B. Martin

Ask your "inside man" to press the brake pedal until it is all the way down. The pedal speed is really under your control. If you open the bleed screw a lot the pedal goes down in a flash. If you just "crack" it open the pedal goes down slowly. The important thing is that the "inside man" does not release the pedal until you call out "up!". If he releases the pedal before you have closed the bleeder, air will be drawn through the open bleeder and into the hydraulic system.

B.C.

Thanks Daniel.

I did indeed observe that the "speed" was under my control and was careful to make sure the valve was closed before the "inside man" released the pedal. If the pedal does however "hit" the floor, this action is within accepted "travel" distances of the pedal, brake booster, linkages, etc. so as not to strain anything, right? I checked a Motor Trend article I had on changing brake fluid and it did in fact instruct depression of the pedal to the floor during valve open step so I imagine this is acceptable.

2dino

B.C. & other members,

May be I am a bit over cautious. I would suggest against pressing the brake pedal all the way to bottom when bleeding brakes.
Reason being, in regular operation, the pedal will only reach may be an inch or so from the floor leaving a section of the centre rod of same length inside the master cylinder never rubbing against the seal. Given time, surface of this section could become rough due to corrosion compared to the length that rubs with the seal everytime the brake is depressed. Pedal to the floor brings the rougher section against the seal and could cause seal failure down the road.

A thin piece of wood under the brake pedal serves me fine when I breed the brakes with a helper doing the footwork.

Just my observation and not meaning to scare you. I am sure most would not run into problem if their brake fluid is replaced on a regular basis.

2dino

B.C.

Since the pedal moves beyond the normal "stop" point during the two man method anyway, wouldn't normally unexposed sections of the center rod rub the seal anyway? Has anyone else encountered the block of wood approach?

Thanks