A question about bleeding brakes.

[Fatherof2]

Hello All,

I have a few questions about bleeding my brakes. I did post in the "Sticky" thread above, but did not get an answer, so I thought I would start another thread. I have also done a search, but I still have some questions.

1. I have read on these boards that some people have bled their brakes by using the "gravity method" only. Meaning that they hooked a hose to the bleed valve and opened the resevoir and let it flow out. They also opened the master, but did not pump the brakes etc. This seems simple. Is this plan reccomended? Does it work?

2. Is a pressurized bleeder better? Is it easier?

3. Do I have to have the wheels off to do this?

Thank you very much,

Merry Christmas,

David

[jestmaty]

It'll be interesting to see what people say....

I caught a local am talk radio 'car dr. type of show' a week back and heard the tail end of someone discussing the gravity bleed method.

I didn't get to hear the main discussion, but it got me to thinking about how ABS and stuff might hinder the gravity bleed process.

I'll be watching this thread to see if any pseudo-experts have some thoughts..

[whizmo]

If the "gravity feed" method works at all, I'd be surprised if it works fast enough to be useful. When I crack the bleed valve on the caliper with the master cylinder reservoir open, I haven't noted much (if any) fluid moving due to gravity. Maybe I'm missing something.

There are three basic tried-and-true methods: manual (two person, pumping the brakes), vaccum (mity-vac or similar device at the calipers), and pressure (device that pressurizes the master cylinder). I think any/all will do a good job - I use the vacuum method with a mity-vac as it works across lots of vehicles with differing systems and without specialized tools, and it amenable to one-person maintenance. But if you want to invest in a pressure system, people seem to like them.

You might be able to do it with the wheels on, but unless you have a lift, I'd suspect it would involve a lot of uncomfortable groveling under the car. I'd remove the wheels.

- Mark

[Fatherof2]

Mark,

Thanks for your input.

I think I am going with the two person system. My only question at this time is this:

Do I need to keep the block of wood under the brake pedal at all times? Does it remain there even while my wife is pumping the brakes? I am a little unclear.

I hope to tackle the job one day next week.

Thanks again,

David

[whizmo]

Originally posted by Fatherof2
Do I need to keep the block of wood under the brake pedal at all times? Does it remain there even while my wife is pumping the brakes? I am a little unclear.

I'm not aware of any need for this. I assume it is to limit the travel of the brake pedal? Every car I've manually bled, I've just pumped the brake to build pressure, held pressure while the bleed valve is cracked, and then pushed the pedal to the floor, holding it there until the bleed valve is re-tightened. And that's the way the Pilot shop manual describes doing it.

But I've never used the manual method on a Pilot.

- Mark

[Fatherof2]

Mark,

After reading several posts, I keep hearing that I need to place a block of wood under the brake pedal to prevent it from going all the way to the floor, and damaging the master cylinder. I am just not sure what that is all about. Others dont use a block of wood at all. I just want to be clear before I begin.

D.

[N_Jay]

The issue is:
Since you normally don't use the full stroke of the master cylinder, the last small amount may build up some corrosion.

Since when you are bleeding brakes there is very little back-pressure on the peddle it is easy to push it all the way down.

Assuming there is some corrosion, and the person bleeding the brakes pushes the peddle all the way down, you could get some wear or abrasion of the seals, causing them to fail soon after the brakes are bled.

Hence the block of wood top keep the peddle from going too far (or at all) past the normal range.

[Fatherof2]

Thanks N Jay!