Blue1991

Hey everyone, been having some issues with my 1998 ls400. Bought the car at 199k miles with 201k on it now and recently started having issues with the power brakes. In the beginning it seemed like the vacuum would deplete after a couple pumps of the brakes and it progressively got worse until the power assist went away completely but the brakes still functioned manually. Not sure what kind of booster was on it, it was some generic no name silver design. I replaced it with a black oem unit from a wrecked 1997 ls400.

The install went fine and everything went well until the test drive. The brakes seemed to lock up so i limped it home and I adjusted the pin on the master cylinder side. When I unbolted the master cylinder the brakes all released and the car rolled a bit. The pin is adjusted all the way down, as short as it will go. Once I take it for a drive, the brakes lock up again. It also idles strange and died randomly a couple times. After the brakes locked up and I let it idle, it idled fine.

What do you guys think the issue is? Is the brake booster from a 1997 incompatible? Or maybe its bad too? Master cylinder issue? I only replaced the booster and used the master cylinder that was on the car already so i didnt have to bleed the brakes.

Any help would be appreciated! Thank you!

paulo57509

This is most likely the problem:

From 1998 OEM Parts Catalog



From 1997 OEM Parts Catalog

Blue1991

Well shoot I guess I'll try a new one and see what happens. I thought the 97's were the same. Thank you!