advsystems

Yesterday I installed steel-brake lines on my 99 GS4. When I finished the rear and went to bleed/flush them, I was amazed at the nasty, yellow/creamy, viscous fluid that came out, along with huge pockets of air. This was identical for both the left and right side rear brakes.

Given the fact that the rear rotors showed no visible signs of wear after 32k miles, I am left to conclude that the rear brakes were more or less non-functional. The brake system, up to this date, had never been touched.

I flushed the entire system with Motul 600; what a huge difference in braking. Whether my brakes were a fluke or not, I don't know, but after a brief stint last night, the rears rotor are already showing signs of wear.

Might be worth checking out on your GS4.

Mr GS400

I don't know what the 'brake distribution' (Front vs. Rear) on a GS400 is but I'd guess the braking is dramatically biased toward the fronts. I was really surprised when I saw the size of the rear pads; they are 'miniature'. I know my rears are working since the rotor faces are 'shiney'. Like yours they show no signs of wear after (in my case) 26K miles.

Don't know what the 'milky' fluid you saw comes from but I'll be doing my brakes in a few weeks (as soon I get the SS Hoses from Steve @ Carson Toyota) so I'll let you know if my GS400 looks the same. I expect to see a semi-clear brake fluid. Maybe slightly darker from reaction w/ the rubber hoses.

Air pockets in a brake system arent' good since they (air) inhibit the hydraulic action. My brakes are feeling a bit 'soft' and pedal distance appears lower.

I think I'll stop here (no pun intended).