is300forev

My wife has a 2001 IS300. The vehicle has 100k miles on it and has been fully serviced per manufacture's specification. Saturday, she's in a drive-thru and she hears a loud humming noise so she turn's the A/C off to see if that stops it and it didn't. Two seconds after that, white smoke starts coming out of the hood at the very front of the vehicle on the passenger side. She immediately checks her engine temps and it looks fine, so she reverses out of the drive-thru and turns the vehicle off. We towed the vehicle to the dealership and asked them to diagnose the vehicle. The dealership cannot find anything wrong with the vehicle and has driven it 10 miles now without any loud noises or any smoke. Any ideas from the community on what could have happened? My best guess at this point is some fan up in the engine compartment that made a loud noise, smoked out and then died or a small animal jumped into something under her hood and burnt up. I'm going to ask the dealership to let the vehicle sit in the sun, while idling to see if it reproduces the issue, because afaik, they've only driven the vehicle or let it idle in a garage (in shade) with the hood up (plenty of ventilation), that didn't reproduce the same cause that may have happened in the drive-thru. Any ideas from the community on what it could be since I'm no mechanic and have zero clue what's under the hood of one of these things?

jadu

iTrader: (42)

If the dealer cant replicate or can't find anything wrong, it is possible that she did run over some debris that could have gotten under the car. The fans could hit causing noise, and the extremely hot headers and catalytic converters can smoke it up.

is300forev

I looked under the vehicle before it was towed and couldn't find anything. I also considered a lizzard or something jumped up under there, but who knows. The dealership still hasn't called back yet, so I guess we'll see if they come up with anything and if not, drive her till she breaks :\

is300forev

So the dealership spent 2+ hours diagnosing the issue and couldn't duplicate the issue and claims the vehicle isn't making any noises it's not supposed to. My wife has the vehicle back and claims it's still making the same noise that it did in the drive-thru before it started smoking. She's bringing the vehicle to me now so I'll finally get to check it out myself, but the dealership said at this point that there's nothing they can do and that "their best mechanic couldn't find any issues with it." The dealership didn't charge us anything for the diagnosis. I'll update the thread after I test drive it.

EDIT: I was able to hear the noise and feel the vibration. The paperwork that we received back from the dealership mentions "Alternator Noisy, Excessive whining noise heard, alternator is charging ok". The noise and vibration are constant and do not go away. If it was the alternator making the noise, wouldn't it go on and off as the alternator turns on and off or would it remain constant? If it'd be constant, then I'm leaning towards replacing the alternator to see if it fixes the problem.

Also on the paper work mentions "Clicking rattling noise heard". The clicking noise sounds like it's coming from the top of the engine. This is an engine noise that I feel was always there, but I am not certain. The main noise that is new to us is the high-pitch engine noise. I will say that if the vehicle is in park/neutral and we rev the engine, the noise follows along with the engine. In other words, it gets louder as you rev the engine (as does the clicking noise). When you let off the excess revving and let it idle back down, it drops down with the RPM and then takes a very short and slight dip and then revs back up to idle. I'm pretty sure that is normal, but not positive.

Any ideas what it could be with this extra info? Thanks for any and all help.

EDIT 2: Was able to bring the vehicle to my mechanic today and he thinks it's the alternator. When the headlights turned on, the noise got louder. He removed the timing belt and the noise & vibration completely went away. He's replacing the alternator now.

EDIT 3: Alternator has been replaced and the vehicle is whisper quiet again. The vibration has also vanished. Problem solved.

jadu

iTrader: (42)

^^^ glad you were able to find more clues and get it resolved.