Summary: On cold start, I hear a screeching sound coming from behind the dashboard of my 2000 GS300. The first day it happened, about four months ago, there was just one screech, but last week it had increased to a series of about 30 screeches. Audio file is attached.

Details: The sounds started the first morning after all three A/C servos were replaced (by the dealer). The number of screeches increased linearly over the past four months. The occurrences had been very consistent--every day and only on cold start. Only once did I hear the sound mid-day and it was minimal. However, in the past week there have been several days without sound. The only correlation I can think of is that up until recently I drove the car at least two hours each weekday and starting a few weeks ago, my drive time has been reduced considerably.

History: I bought the car ten years ago from my parents (@70k miles). It now has 150k miles and the only other repair I've done is replace a few ball joints (also done by dealer).

Additional info: There are no warning lights. The car drives beautifully; I drove it 1500 miles round-trip to see the eclipse last month, including a grueling 65-mile stretch that took 6.5 hours. Everything about the car feels perfectly fine.

Dealer's initial diagnosis: The master cylinder and brake booster need to be replaced ($4000). They will start the car again tomorrow morning with someone under the hood to try to pinpoint the sound.

 

Its not the complete booster, but the master cylinder.

Mine has been doing it for about 6 years now. IDGAD LoL Car still brakes just fine. Its more of a nuisance than a problem, however, being that its brake/safety related, its definitely something to consider fixing. Everyones experience is relative, so just because my car has been event free, doesn't mean yours will be the same. The noise, IMO, doesn't mean its bad, just old and making noises. As said mines been doing it for a good 6 years, however when I drive, I'm always ready to hit the E-brake. If you have family, look into replacing the master cylinder. I'm always alone so I don't have to worry about endangering anyones life.

Do a search on master cylinder to get all your options. Personally, I've seen about 3 threads on this within the last 5 months or so,

 

Thanks for the input. Yes, I've read many posts on the topic. However, I didn't find any that seemed to be an exact enough match to my problem for me to feel comfortable agreeing to a $4000 repair on a car only worth $3000. I'd like to have as many eyes an ears weigh in before I decide what to do. I plan to take it to an independent mechanic to give a second opinion.

 

You'll want to find a used/refurbished master cylinder on eBay ($250-$500) and have an indy install it. Most familar with Lexus vehicles can do it.


The dealer only does new. For example, they quoted me $1,372 to replace the radio door assembly on my SC! I found the part used on eBay for $200 and did the work myself.