Brake Booster Gone Bad?

tony_lexus · April 11, 2014

Hi folks,

My car LS400 1999 with 142K miles has code P171 (system running lean) due to vacuum leak. With an OBDII reader watching the trimming (long and short trims), at IDLE it is way over %30 in total for both banks. If I press the accelerate pedal, the trim went down to < %10. My mechanic did a check and he told me my brake booster is bad (after $700 replacing the intake gasket). To prove it he clamped the vacuum hose that connects to the booster from the intake, at idle, I can see the trimming gone down to < %10. Now comes the hard part, he want +1000$ for replacing the booster with re manufactured part and almost $2000 for OEM one. Ouch! I think I can handle the R/R for this thing once the weather is nice enough

So here are some question for experts out there:

1. Is re manufactured brake booster , particularly from CARDONE A1, any good? Or should I look for an used OEM one?

2. How easy to get access to the 4 nuts inside cabin to take out the booster? I download the service manual and it seem not that hard but want to tips/opinion from expert out there.

3. is it possible that the master cylinder might be the culprit and cause the leak?

Thanks a lot

Tony

landar · April 11, 2014

Tony, I do not know how hard it is to replace the booster unit but it is not related to the master cylinder. If you had a leak there, you would be bleeding brake fluid.

I would carefully check the vacuum hose and clamps leading to the booster unit for leaks before declaring the booster bad. Could be a hose or defective clamp.

If the booster is bad, a junkyard unit might be the best bet if you can find one.

sha4000 · April 12, 2014

I too, was thinking the junkyard also for an affordable replacement.

dcfish · April 12, 2014

A bit of advice...Find the entire pump/accumulator/ABS/Master cylinder assembly Ebay/Junk yard etc...Replace the assy. as one piece.Trust me on this one....

billydpowell · April 15, 2014

never had a problem with any of mine and have never had a problem with CARDONE A1 either... when they are rebuilt, only the diaphragm is changed, but it would be nice to know if it was USA or ???? who knows..