Brake booster help..wtb? (1 Viewer)

[lastresort576]

'97 lx450 221,xxx miles on the clock -Part time converted, stock ride height OME springs.


Hey guys I posted this up on some of the FB forums but figured that I would check in here with my problem and test results.

I've got potential signs of a failing Brake Booster on my 80-series(really hope its not)

Occasional normal brake pedal feel, then get's super hard, goes normal again..sometimes even in the same depression stroke. I also feel like I can hear a slight hiss on occasion as I depress the brake pedal, in the brake pedal area. Of course this Hiss seems new to me, but that could of course just be that I never noticed it until now that something is malfunctioning.

Yesterday, I drained some brake fluid out of the MC because the level was over the Max line (did a bleed on old pads, now have new=raised level). And now the problem has shown it's face first drive since the drain.---->>>I tried to bring the MC back up to around the same level it was before I drained some of it and that made no difference.

Could a Vacuum leak also cause these symptoms? All my hoses/lines look decent, but who knows.

***Also, I did all the Brake Booster function checks in the FSM. Seems to have failed 3 out of the 4. The only one it passed was: BR-15 1.a) ---->>> (Depress the brake pedal several times with the engine off
and check that there is no change in the pedal reserve
distance.)

To add: my MC fluid level never showed signs of leaking....

Oh and if anyone possibly has a Brake Booster near Northglenn, Colorado theyd like to sell, LMK.

 

[mdawg]

I had the exact same symptoms late last year: soft braking, followed by hard, almost impossible braking. Oh, and the "hissing" sound when depressing the pedal. I replaced the original booster with a refurb'd unit from NAPA and that fixed my braking problem. I also replaced the master cylinder "while I was in there", but I believe that the old MC was just fine. Given your symptoms, the common culprit here is the brake booster, IMO.

 

[Mud crawler]

Mine does the exact same thing I wonder if it's just a vacuum leak.

 

[lazy]

id replace the check valve on the end of the booster before I thought about the booster itself. it's got to be worth a couple of bucks to do that before you do the booster imo.

 

[lastresort576]

Alrighty. In the morning when I get home from work, I'm going to test the check valve and do another check on the B.Booster. Since I only passed one of the fsm tests if I fail these next tests Im gonna pick up a new B.Booster.

1. I'm going to try and run the truck for a min/two.
2. Kill the engine.
3. Remove the Vacuum line to the B.Booster.
4. And listen for air sucking into it.
(Supposedly since no air in the B.Booster should be present after running the truck and killing it..
when I remove the vacuum line I should be able to hear it sucking in air.)

Fingers crossed...!!!
Really don't have any $$ to throw at this truck which is my DD too so gotta get it fixed ASAP and on the real cheap. Thinking CL. :/

 

[lazy]

There seems to be a guy in Parker parting out cruisers all the time. He's on Craigslist.

 

[lastresort576]

There seems to be a guy in Parker parting out cruisers all the time. He's on Craigslist.

I didn't find anyone in Parker(not yet at least), but there's a guy in castle rock that's parting out an LX450 supposedly with 88k on it.
He wants $175 for the booster/MC...feel like it's a bit steep, but it's not a remaned part..so maybe worth it??

 

[lastresort576]

Ok so ended up getting a b.booster from Yoda Jim's today for $75. The part ended up already being a reman too so fingers crossed itll be good to go. Got the booster installed and just waiting for help bleeding the system. So far the pedal feel even though not pressurized yet, feels much better and I'm not hearing that hissing sound anymore.

I did test the check valve, and it felt like it was sticking slightly. But I couldn't picture that it was sticking so hard that it wouldn't continue to work properly. I cleaned it up with from brake cleaner and the sticky'ness is all gone.

Ill check back tomorrow after I get the system bled and test driven to confirm that the booster was the problem. Thanks for the help guys.

 

[lastresort576]

Figured I'd put a close to the thread.

It was definitely the brake booster that crapped out. Got the 'new' one installed, bled up, and it's working as it should. Hopefully this one lasts a good while!

Thanks for the ideas/suggestions guys.

 

[Phildoh]

Had the same problem the day after I bought mine. Booster was shot, AND, not related to that but my PS the same day as well. For the record, if you very carefully unbolt the mounting bolts for the master cylinder, there's enough room to get the booster out without removing the MC. Just gotta be super careful and slowly bend it outta the way. Saves hours of bleeding, and brake fluid mess. My MC was only a year old or I'd have changed it at the same time. Happy brake fix!

 

[Reg Wang]

I have a 200, LX570, I may start anew thread over there. But, “hissing” was the key word here.

So, I don’t think my brake is “mulfunctioning”, car stops, pedal depression consistent, pedal resistance also consistent. BUT, there is ALWAYS this hiss when depressing the pedal. Picture this sound in your head: like that rotating office chair? When you raise it or lower it, you can hear that hydraulic/air getting released or sucked in, the same sound. Furthermore, the “PSSSSS”, is sometimes followed by a electric sounding, lower noise when the car is at a stop.

 

[Sc0-]

Thought the 200 used a electrobooster for the brakes?

 

[terrance lim]

i hop your booster last longer than mine I got mine from autozone about 1year and it go out on me. if i have to do it over I will go with oem i know it cost more but it will last you more than 10years. save time on wrenching and go wheeling better

 

[1973Guppie]

i hop your booster last longer than mine I got mine from autozone about 1year and it go out on me. if i have to do it over I will go with oem i know it cost more but it will last you more than 10years. save time on wrenching and go wheeling better

Brake master and boosters always go OEM..............