I tried replacing the power brake booster on my 1999 Grand Cherokee Laredo. Got the part and put it on, and the rod that goes to the pedal did not go back far enough to push the brake light switch, also the brakes were very weak. Bled the brakes, and had the same scenario. Then undid the job and put the original booster only to be amazed at the fact that its rod apparently ‘shrunk’. It does not reach the needed length to push the brake switch and the power is also gone.
What’s puzzling is that even the old booster does not push the pedal back enough, and it did so before I messed with it, which I did because of an air leak.
I have bled the brakes thoroughly, with both boosters on, I have made absolutely sure that the booster is flush against the firewall, yet it seems the rod has shrunk.
I have replaced several booster in GM cars before, this is my first Chrysler and I am utterly lost.
I went over it again and removed the whole assembly, then broke it down to leave only the booster, I made as much clearance for it as possible by removing the air cleaner assembly, all the brake lines and everything that could have gotten in the way and I am absolutely certain that both boosters, original and replacement are all the way against the firewall and both of them fail to reach the needed distance for the pedal to actuate the brake light switch or to travel enough distance to push the piston in the master cylinder all the way in.
The question remains: I put the original booster exactly as I took it off, even have pictures of the process, and the rod is not reaching. It was working fine before, except for the whistling leak.
Open to suggestions… what else can I try?