fairly high pitched mechanized noise

So I just bought a 2002 Prius with 110,000 miles on it. Everything has been great about it, except that it has recently made a high-pitched mechanized noise for about 2 minutes while driving on the freeway. The car's functionality is unaffected, and there are no warning lights that have come on. After about two minutes, it stops. This has happened three times now. I say it sounds mechanized because it almost sounds as if the radio antenna on a car were going up but it was having difficulty, like an electric motor running into problems.

I spoke to a mechanic, and he said that I could bring it in but he would be worried about wasting our money because it would be so hard to identify if he can't see/hear it while it's happening. He doesn't think it's a belt problem because the noise would last for a longer time. The one suggestion he had was to shut off the air conditioning (which was on at the time) to see if this stops the noise.

Any ideas or suggestions? I hesitate to bring it in to a mechanic when I don't have some vague idea of what might be wrong with it, otherwise I get worried about being charged for things I might not need fixed (I don't have a mechanic I can trust yet, having just bought the car).

Thanks in advance for your help, everyone was extremely informative and helpful with my last questions, and I'm still excited about the car.

 

<div class='quotetop'>QUOTE(D Rock @ Jul 15 2007, 09:16 PM) [snapback]479387[/snapback]</div>

Thanks a lot. That's a great way to start because I'll have an idea of which part is associated with each step. I'll write down the list and bring it with me into the car to run through if and when it happens again. We'll be driving down to the South Bay from SF tomorrow so I'll give it a try then. If it's just something to do with the AC I think I would feel better about that than an engine cooling fan, say. But what do I know.

Thanks again, and if I find out I'll post it here, maybe it will help out someone else.

 

So an update for anyone else interested:


I just took it to a toyota mechanic today to get a complete rundown.

Before I took it in, I did some of the tests that D Rock smartly suggested. The noise happened again, and I one-by-one shut down the AC, then the fans, then put the car in neutral, and then parked the car. The noise kept going. I got out of the car, and it was clearly coming from the back. One mechanic thought it might be a cooling fan back there, but found no problems with it when he looked at it. According to him, everything physically checked out OK.

Two warning lights also came on, the first was a turtle, which came on right when started the car. Eventually, it went off, the next warning light was the check engine light, and the mechanic said it needs a new catalytic converter. I'm wondering if this isn't related to bad 02 sensors? Anyways, bad times. He guessed it might cost 2200 dollars, and I'll have to find out more about how a broken converter affects the car. The car is of course past warranty, so it looks like I'm going to have to spend quite a bit of money to fix everything..

Any advice on how to proceed? There's no history of defective 02 sensors or catalytic convertors in 2002 Prius are there?

I'd appreciate any help, I was hoping this car would last thruogh grad school without a major repair, but I knew there's a risk in buying any car with more than a 100K miles on it.

Thanks again all, this forum has been a big help.

 

Peter,
One thing for sure....if your cat is clogged it will bog down the engine and you may or may not see reduced power. If you actually need to replace the catalytic converter then do not take it to Mineke. You have to tell the muffler place that you take it to......that you want a HIGH OUTPUT catalytic converter installed or you need to buy one from toyota or you can buy one used at a junkyard specifically from a smashed prius that had low miles on it when it came in. You do not want to make the mistake of putting in a discount cat conv in the car.....IT WILL FAIL WITHIN A YEAR AND YOU WILL BE BACK TO THE DRAWING BOARD AGAIN. To be more specific about the cat conv...if it is clogged or partially clogged then the exhaust gasses from your engine can not exit the vehicle and the combustion process becomes strained.....especially when you need the most power from the vehicle. I can not attest to the noise it is making. Only way I know to ensure that is when you get the bad one cut out of the vehicle you need to inspect it. Make sure you mark what is the side that goes in and the side that goes out for inspection purposes after they cut it out with a torch or other metal cutting device. You should be able to see the millivolts on the O2 sensors being very low on the engine side of the cat and higher values on the exhaust side of the cat. I do not know if it has a pre and post O2 sensor or not. Do you have a chilton or haynes book on this car yet or is one even made yet? I have to drive to Florida this weekend but I will be checking email.
Try to PM galaxee with this info also and see what DH has to say if anything extra.



Sorry for the delay in updating. I've been down in Los Angeles searching for apartments before school starts..

The catalytic converter costs 1650 dollars (just for the part) to replace, so I'm going to hold off until I know what my monthly expenses will be like. I spoke to a muffler shop who said, potentially, they could weld out the converter and send it off to be rebuilt for about half the price, but he would have to look at the car first.

The noise in the trunk of the car is becoming longer and louder. The pitch oscillates a bit more too. At one point, on the drive down from the Bay Area to LA, I pulled over and let the noise run for almost ten minutes before it stopped. I'm worried that the fans to cool the battery really are busted, and the battery could potentially overheat, but I'm wary of taking it to another mechanic and paying them money just to have them tell me everything is fine. Unfortunately the noise only happens after drive 2.5 hours or longer.

I'm thinking of calling toyota and asking if they can have a higher-level technician look at it. When I do or if there's any other news I'll update again.

If anyone has any suggestions on how to proceed I'm all ears. Thanks to everyone.

(Oh, and to answer Drock's question, I don't have a haynes or chilton book on the car, not sure if they exist either.)

 

Well, when it rains it pours. The entire ventilation system just went out; as in, with or without the AC, nothing comes out of the vents. Hopefully this is related to the noise, but since the noise is in the back, and not under the hood, this could be more trouble. I'll call toyota tomorrow..

 

Well I think this might be my last post here. I took the car to toyota today and got the full estimate on damage done. New catalytic converter is needed - 1600 dollars, the fan to cool the battery is broken - 550 dollars, and to top it off, the vents need repair as well (I didn't bother to get an estimate). It's very depressing news, because I can't afford to repair this. Essentially, I bought a lemon, and I think the person I bought it from knew it. This is my fault for not figuring it out.

Anyways, I think I'll either to try to sell it online, but of course I would disclose all the problems, but I think I would get a better value than what a dealer would get wholesale. I spoke to the dealer, and he offered me a Corrola with 89,000 miles on it for 8500 dollars, so I'll have to pay 2500 bucks difference.

Anyways, thanks to all for the help, if you have any suggestions on selling this car I'm open. Better luck to everyone else, I'm sure most of you won't need it!