Strange Noises When Start Cold Or Turn On The Rear Defroster

[SHKID]

Hi, All:

I have an issue with my 99' RX300. When I start my car in the morning, especially when temp is cold, I hear this high pitch noise coming from the belts. So, I thought was the serpentine belt. I have one of them (top one) replaced. It stopped for a couple of days, then it starts again. The high pitch noise comes on and off when starting the car for the first 5 minutes. There is no noise driving the car on highway or local. Recently, I noticed something strange. When I start the car and turn on the rear defroster, the noise would come on. When I turn it off, then the noise would go away. I have tried to put some lubricant on the top serpentine belt, but it didn't help. I took the car to lexus dealer for a check. Unfortunately, the noise didn't happen that time.

I really like to know if any one has the similar problem or anyone knows how to fix it. I don't want to pay the dealer $135 dollars/hour labor. I am wondering if I could fix it myself.

Thank you!!

SHKID

[SHKID]

No one else out there has or had similar problems?

[RX in NC]

If a new belt still squeaks at start-up on occasion, it usually needs to be tightened a bit. If you're still running around with your original factory belt after 11 years, tightening it up won't fix the noise because the belt is worn out. You'll need to replace it.

Thinking back to when my wife had her lousy 2000 RX300 AWD and I changed that AC/Alternator belt at about 90,000 miles or so, I believe the primary belt adjustment process worked like this:

There was an easily-visible pivot bolt at the top of the alternator (we'll call it bolt 1).

There was a harder-to-see adjuster bolt on the opposite side down near the bottom of the alternator, towards the radiator (we'll call it bolt 2).

Just below the adjuster bolt was another mounting bolt (we'll call it bolt 3).

If you will tighten bolt 2, you should start to see the belt tighten up as well. You may need to loosen bolts 1 and 3 just a bit in order to allow the adjuster bolt to do its thing. Be sure to tighten up all three bolts after you are satisfied with the belt's new tightened position.

I think bolt 1 took a 14mm socket and bolts 2 and 3 took a 12mm socket.

Keep in mind that I'm typing this information from memory. I remember that I replaced the factory AC/Alternator belt in May 2005, the new belt squealed just a bit upon start-up, so I went back in, tightened it up some more, and the new belt stayed quiet after that. Hopefully someone who's done this recently will jump in here and either confirm my instructions or provide you with a better set. Good luck to you....

[SHKID]

RX in NC:

Thanks for your post. I actually have Lexus dealer tightened the belt after it was replaced (belt was replaced by someone else). Or at least, they said they did. It was ok for a while, and then the squeal started again. Especially when I turn on the rear defroster. I am wondering if I need to have my 2nd serpentine belt replaced as well and why it starts to squeal when the defroster is on.

I will looking into tighten the belts myself and replace the 2nd belt myself.

SHKID