Marc Shaw

I have searched and read every thread I can find but none seem to agree on the best/safest way to flush the bomb (accumulator) nor do they give specific details on how to do this.

Any suggestions on the best way to do this?

I get the impression, one turns on the ignition (but not actually start the engine), let the brake booster run to pressurize the system, then open the bleed valve (briefly) to let some fluid out.

Okay, a few questions......isn't the accumulator under very high pressure and opening it is not recommended when it is pressurized?? Is this safe? Where is the bleed nipple on the bomb? How much fluid should one let out? How often should this be done?

Thanks all.

Marc

Indycam

Why pump it up before opening the brake fluid bleeder ?
What good does doing it at higher pressure do ?

I bleed it at the lowest pressure possible . Less stress .
I put a hose on the bleed nipple , the top most bit on the bomb , crack open the nipple , then run the pump , the fluid goes from the pump into the bomb and then into the hose . Once I see no more bubbles or I see the new fluid coming out the nipple ...

If you undo one of the battery cables you can you that cable as an on off for the pump .

Marc Shaw

I think I found the technique in Adrian's book.

Thanks.

Marc

Paulie964

insert fuse through top nipple, light, step back and cover ears ...

garrett376

Just open the bleed valve, and open it slow as a lot of fluid comes out, fast. It won't kill you unless you open it super fast and your bleeder line comes off then it will spray like a fountain, and usually you're face is right over it. It's easy to fill a small water bottle even when uncorking it slowly! If you've seen my threads, a lot of times it comes out frothy and white when you barely open the top bleeder nut (which has a ring of rust around it on your pic above; with the rubber cap on top - just pull that cap off, and there's your bleeder). I bled this every time I did a brake bleed. It never came out that dirty, but from Adrian's book he states the pump "chops up" the fluid, so I guess it's worth bleeding every so often for preventive reasons. A degradation in the fluid at this point in the circuit only affects the hydraulic boost, and the C4 PDAS solenoids and cylinders.

garrett376

One other thing - by having the ignition on, the pump will re-pressurize with new fluid as you're doing the bleeding procedure which speeds things up and ensures new fluid in this part of the circuit. You can go through a lot of fluid that way, so be sure you watch the tank.

tgage

The first time I had ever done this myself, the hose I put on the bleeder valve popped off because of the pressure (it sent a fountain of brake oil up about 3 feet). I learned my lesson to have a tight fitting between the nipple and hose before opening it up. These days, I just remove the tire and everything else out just in case I have to do a clean-up (ii.e.: if you don't want it to rain bring an umbrella.) Some people just run the hose back up to the brake reservoir (but that defeats the purpose of purging the system). After doing this once, just close the nipple, then re pressurize the system by doing what you mentioned, turning the ignition on to just before start). Then repeat the process. Doing this twice should be enough to take any air out. I'm assuming you have one of the brake fluid fillers, but if not, keep an eye on the fluid levels.

tom

dfinnegan

The Shop Manuals, section 47 describes this process within the section on Removing and installing the pressure warning switch.

Marc Shaw

Thanks all - I'll give it a try (and I read about it in the WS Manual too).

Marc