Newbie Master Cylinder/Booster Question

[TMILL]

Officially new to board but have been lurking for a while.... have gotten some great info enabling me to make some repiars... thanks.
Have a 98LX for about 3 months now.... started last week when I first start it in the morning there is a screech from the master cylinder or booster.. almost sounds like a belt trying to catch up to a pully ( I know there's no pully involved... just explaining the sound)... lasts about 2 minutes... then goes away and all fine... brakes work fine... this morning (much colder outside) lasted about 4 minutes and ABS light went on.... turned off and restarted - all fine... I've searched around the site and see the $1.4K replacement, ouch!!! I'm thinking Booster motor or accumulator???
Any ideas, tests I can run?? Thanks.

 

[100 TD]

Doesn't sound good, probably the motor, I think it has been mentioned here before that the motor is 1000, the master cylinder is 1000, the accumulator is 1000, or you buy the whole lot for 1400, (something like that anyway, do check the prices). I doubt changing out the fluid would help, I expect you are up for the $1400 and a couple of hours to change it. Just remember if you are driving and the motor fails you should still have brakes for a few pushes of the pedal until the accumulator pressure drops, but be aware that braking may get very hard as it drops.
Do a search, you may find others that have changed them out and may have done a write up, or the prices they got.

 

[cpcc]

I agree, this doesn't sound too good. My big concern is that I have not heard of many accumulators failing. You may want to make sure that it is not the serpentine belt. A little belt dressing may save you alot of money.

 

[Jim_Chow]

According to my manual, if the booster fails, you will only have reduced braking pressure at the front calipers and ZERO pressure in the rears. I think the master unit w/ booster is around ~$1.5K. IIRC, the manual says to disconnect the abs/brake ecu before removing the master unit. Unfortunately, all the toyota med-size and larger SUV's use them now, including the 4runner.

 

[NMuzj100]

Do you hear this before or after you start the engine. The brake booster will bring the pressure up with just the key at "on" w/o starting the engine. This could help you to isolate and troubleshoot.

If you wanted you could bleed from a wheel to reduce the pressure and then have an assistant bring the key to "on" while you listen.

In a attempt to save having to shell out the $1400 I would also check and make sure the electrical system is sound before replacing the booster. (free check usually and good to do anyway) If the booster was not getting enough power that could also create a problem that would be aggravated by the cold. Check all the electrical connections and grounds.

 

[Jim_Chow]

The booster shouldn't make any screeching sounds. It will make an electronic servo/motor sound (just like the factory diff locks, but continuous) when you turn the ignition on (but engine off). You should hear the motor go for about 30 sec or less as it builds up pressure in the system. This is normal, but a screech isn't.

 

[TMILL]

Thanks for the input.. tried it this morning w/out starting it... no screech but did hear a slight "higher" pitched noise only near the end of it pressurizing.. seemed to be from the motor vs. accumulator.. being electric there wouldn't be more pressure w/ the engine running, would there?? also, any idea if the $50 master cylinder rebuild kit includes parts for the motor?
Thanks

 

[cpcc]

Last I checked, there was no rebuild kit available for this.

 

[NMuzj100]

TMILL - sometimes the parts counter will show 80 series parts for your 98 because a few 80 series were considered 98 models.

 

[TMILL]

someone on another thread had mentioned the kit and I found one here:
http://www.mylexusparts.com/index2....tion=selectCatalogYearMakeModel&siteid=214281

says it's for an 98 LX?

 

[100 TD]

THREAD HIJACK!

This site mentioned the kit is suitable for 98 to 05. I would be interested to know what is in the kit it if anybody gets one, I would pressume it would contain all cups, boots , seals and springs for the master cylinder. (I doubt it would contain anything else, although I would like to know what is in it.)

someone on another thread had mentioned the kit and I found one here:
http://www.mylexusparts.com/index2....tion=selectCatalogYearMakeModel&siteid=214281

says it's for an 98 LX?

 

[TMILL]

i emailed asking........ will post if/when they reply

 

[TMILL]

Here is the reply:
THE PART NUMBER FOR THE BRAKE MASTER CYLINDER KIT FOR YOUR LEXUS IS 04493-60330. THIS IS BASICALLY AND ONLY THE PISTON AND SEAL AND CONTAINS NO BOOSTER PARTS. PLEASE NOTE THAT SHIPPING AND HANDLING ARE ADDITIONAL. THIS PART IS NOT IN STOCK PLUS IT IS ON BACK ORDER WITH LEXUS AS WELL SO IT COULD TAKE IN EXCESS OF TWO WEEKS TO GET A HOLD OF IT BEFORE WE COULD TURN AROUND AND SHIP IT TO YOU. THANK YOU