shaft1

I've read LexLS.com guide on how to bleed the brakes on our LS. The fluid in the reservoir looks kinda brownish.

It was never mentioned if the ngine should be running or not while bleeding the brakes. I apologize if this is a dumb question but I've never flushed a brake system before.

Whats the correct procedure? Engine on or off?

How many quarts of brake fluid do I need to completely flush out the old fluid -- 1999 LS400.

thanks.

PureDrifter

iTrader: (10)

doesnt matter, I tend to do it OFF but the only difference is there's no boost when it's off. Plus it's easier to tell when the pedal firms up.

LS400BOY

i want to get ride of all the old fluids to,is it possible to just open 1 valve and then pump brakes to get ride of the older fluids while adding new fuilds when the older fluid gets low so it wont add air into the system?? them do individual wheel??

RA40

iTrader: (6)

Suck the old fluid out of the reservoir. Depending how old it is, there can be some nasty particulates floating in there. You'll want to get that out so it isn't pushed through the ABS. You won't get the stuff in the forward chamber out but back two are prone to more to oxidation and contamination since these are closer to the fill cap.

cobalt91

I've noticed a bleeder on top of the ABS pump. Does this also need to be done during a system flush/fluid change?

RA40

iTrader: (6)

I've not had to do it in my brake bleeding. If you were replacing the ABS unit and needing to evacuate any air that may be in a new or opened system.

cobalt91

Thanks guys.

shaft1

To me it makes more sense to have the motor running so the boost is avialable for better flow.

Can anybody pls tell me the amount of fluid I need to have in order to get this job done? thx.

RA40

iTrader: (6)

One big bottle is sufficient for me. This will vary on how much you pump out to clear the lines. I also do it with engine off.

shaft1

Excellent. Apprecaite the clarification.

LS400BOY

i bleed mine with the motor on,and yea 1 bottle is good enuff