How To Replace Brake Booster?

[lsrxlex]

Hi all,

I plan to replace the Brake Booster on my 1990 LS400 (with 280k miles).

Please help.

Do I have to bleed the system afterward? Is there a way to avoid that?

Thanks for your help.

[steve2006]

Hi all,

I plan to replace the Brake Booster on my 1990 LS400 (with 280k miles).

Please help.

Do I have to bleed the system afterward? Is there a way to avoid that?

Thanks for your help.

To remove the booster you will 1st need to remove the brake master cylinder and in order to do that you have to disconnect the brake pipes to it so yes you will need to completely bleed out the system after.

It's probably a good thing as the brake fluid should be changed every 30,000 miles so this would be a good time to do so.

On reinstallation make sure the brake booster push rod is set correctly.

[lsrxlex]

My car has TRAC control, do I need to bleed it too? If so, please show me how to.

Also, since I have to bleed the system, may be it's time to switch to synthetic brake fluid (?). Is that a good idea? What kind of synthetic fluid should I use, if the switch is OK with this old car?

Thanks for your promp advices.

IronToad.com just let me know that Booster for 1990 LS400 is no longer available.

Can I use the one of the newer model year of LS400? 1994, maybe?

[SRK]

When you remove the master cylinder, plug the lines with small rubber vacuum caps, and lay the cylinder on its side so fluid doesn't run out. Replace the booster. When you re-install the master connect the lines quickly and tighten gently. Have someone press the brake pedal and loosen the lines one at a time from the master. You'll bleed the master and the lines right there. There is no need to bleed the rest of the system as long as it doesn't drain out while you change the booster.

I've installed new masters on many cars over the years, and I have never pulled a wheel - just bleed it at the cylinder.

Don't change fluid - stick with DOT 3 or DOT 4. Don't use anything else.

Keep the job simple.