newgsman

iTrader: (4)

Some of the guys on the ISF forum have also resolved this by replacing just a valve on the booster. Apparently it is a common issue with several Lexus and Toyota cars. I figured that's what the dealer needed to do with my car but when they said they were going to change the whole booster I didn't complain.

shaolin

iTrader: (2)

Are you able to find the part # from the ISF form just for the valve?
How many miles on your ISF when it happened? I have over 200k so not sure if it's time to replace the whole brake booster...

Soledad

The Part Numbers for the check valve and rubber grommet on my MY08 IS350 are:

Check Valve ($31.69) - 44730-28010
Rubber Grommet ($2.68) - 90480-24015

A brand new Brake Booster from Lexus (PN 44610-53290) is $504.77. An A-1 Cardone brake booster is $198.79 + $50 core charge.

Oh and my car has 66,000 miles on it so I don't believe the issue to be a mileage or usage problem but probably more of an age related problem.

CharonRega

Not been impacted by this issue but if it occurs, does it get worse with time until it is fixed or is it typically just a minor annoyance that doesn't have a larger scale impact?

Soledad

I've read of a few that weren't able to press the brake pedal hard enough to allow the car to start. So major annoyance there. However, I'd say most are able to press the pedal hard enough to get the car to start. For me it's a minor annoyance just because I'm having to press that pedal pretty hard. But, what I don't know is how a new check valve or booster would actually change the effect or feel of braking. Braking feels normal to me but not sure if having a properly functioning brake pedal/booster would make braking feel much better or not.

I think I'm going to replace the check valve and grommet after Christmas to see if there's any change. As a baseline, if I drive my car in the morning and then go to drive it again in the late afternoon, the brake pedal will be somewhat hard to push in at start and will have very little travel. If the car sits for a few days the pedal is very hard to push and has almost no travel.

shaolin

iTrader: (2)

Thanks found the part and might give this a try. I hope simple valve and grommet can do and not spend over 500 plus huge labor. So all the ISF guy replaced the valve and grommet and fixed the problem? Or did anyone replace valve and grommet and later found out need to replace the entire booster?

CharonRega

Yeah, that's pretty severe. I wonder if the people who couldn't press hard enough to start had experienced the problem earlier and it worsened. Either way, I'm with you on fixing it. Sounds like a major hassle.

redspencer

iTrader: (1)

I've had this issue on my IS350 for well over a year and while I've had no problems not being able to start the car, my brake boost pressure would easily bleed away within 1-2 hours each day. After starting up the car, the brakes behaved normally so I delayed in remediating this problem.

I very recently decided to finally swap out the grommet and brake check valve (less than a month ago) and now the brakes are holding pressure the way they should be.

Definitely look into replacing your grommet and check valve as a low-cost troubleshooting step to see if it will help resolve the problem.

newgsman

iTrader: (4)

My car is a 2012 and had only about 25K on it and still under warranty so I didn't really have a problem with them replacing the whole booster.

shaolin

iTrader: (2)

Wow, at 25k only? Mine's got around 220k and this happened around 210k. I just received and replaced my Booster Check Valve and Check Valve Grommet today hoping it will fix the problem. Did a test ride around the block it feels nice but only tomorrow morning i will know if it will resolve the brake pedal stuck issue. Wish me luck!!!

Soledad

Let us know if those parts helped or not. Once Christmas is over I need to give the car some TLC and this is definitely on the list.

shaolin

iTrader: (2)

Sadly it did not fix the problem for me....

Soledad

Damn! Thanks Shaolin. I think I'm still going to get the parts and try this. I don't even want to think about the brake booster being bad. If it is then I'll just live with it until I can't start the car which may or may never happen.

professorm

2013FSport

iTrader: (2)

I know this is from 2016 but what has not been answered is how does this impact safety and driving.

When the engine is running it acts as a vacuum pump. Now as long as it's running, you *hardly* need the check valve. But should it die, the vacuum goes to zero and your power assisted brakes go away. As does the ease of pedal depress to restart the engine. ** note during WOT, engine vacuum also goes to zero. But *usually* we don't need our brakes until we let off the throttle and vacuum is restored for assisted braking.

That said, a minor leak at the check valve whereby 12hrs leaks away the assist vacuum, the driver is not going to notice this.

A leak that depletes start assist vacuum in 20min or less could in fact be a huge safety concern that should first be addressed by new grommet and valve. If still leaking, the booster should be replaced.

DIY people you must verify booster push rod depth into the master cylinder. When the MC is bolted down, there must be a tiny amount of freeplay so the MC is not being depressed by a an overly extended push rod.

If left too long the MC will NOT pull fresh fluid from it reservoir as your pads wear. Over time you will loose your brakes. In some cases the first day or two can lead to brakes that overheat. Whaaa???? As the brakes heat the fluid it expands. If it can NOT return to the MC reservoir, the caliper pistons DO NOT RETRACT and the brakes over heat.....

Place clay at the end of push rod. If when the MC is bolted down, the clay is smashed flat, you have Zero clearance and must shorten the pushrod.