2009 Corolla Purring When Idling And Parked After Driving

sounds like a purr of ups and downs in loudness but only after driving to warm up, I have tried to have a couple mechanics listen to it but I just now caught on that if I drive it there and then go in to get them and start the car again it will not do it. Also if I just let it idle to full warm up it won't do it either. is this just a common engine noise when idling or is it a cause for concern???? please help!

Pretty common for these engines - both the 1.8L and the 2.4L - probably hearing the valvetrain noise / accessory noise. Nothing to worry about.

As long as the idle falls to the "normal" range - something like 600-800RPMs - you're fine. If it bogging, barely running or racing at 1500-2000+RPMs after fully warmed up - then you have a problem.

thank you so much for the quick reply, its a relief!

No problem I forgot to mention in my previous post.

If the noise continues to happen and you want to fix it right - double check that it is not the serpentine belt that is worn out. If this gets glazed or dry rots - it can also cause a weird chirping / purring noise. Each car is different - depending on how it was driven and environmental conditions - I've had serpentine belts wear out inside of 40K miles and some lasting more than 100K miles.

Quick trick - if the car is making that noise - spray or dribble some water on the serpentine belt. If the noise immediately changes (gets worse or goes away) - then you've found the source of the noise. If no change - then it is likely the valvetrain or accessories causing the noise.

Unfortunately, no real fix for valvetrain noise aside from trying different brands of motor oil (stay within the same viscosity range). In the case of the accessories - sometimes a bearing on the pulley will go bad. Idler pulley, belt tensioner pulley/belt tensioner itself, waterpump, A/C compressor, alternator - all are common culprits for excessive noise.

Kind of a light rumbling purring noise? Probably the belt tensioner starting to get weak. It should be worse in gear at a stop and less in park. If you can make it do it and have someone add tension to the tensioner or release tension partially and the noise goes away then it's the tensioner. Not uncommon with 60K+ miles to see them get weak and start the purring rumbling sound.

I got the Serpentine Belt changed out and the sound is still there so I'm not sure it is that. Seems to get louder when parked after driving on the highway for half hour. Its not hesitating or bogging or anything like that. my MPG's haven't changed. Is it something I need to just get over the noise with?? I have had some friends who are mechanics listen to it and their response is to turn the music up and not let it bother you when parked at home or work. It gives me crazy anxiety it is the timing chain that is getting worn out or something the chain runs along that needs to be looked at. Should I do anything about it or wait until something actually happens with the engine or just write it off as being paranoid?

A worn out timing chain won't make a purring sound, even when it is really worn out. Even so - as long as you change the motor oil on a regular basis - that chain will out live the car. Chain guides are the same way - having the oil changed at regular intervals is the key.

Bitter made a good call on the belt tensioner being a possible culprit. On the 9th gen Corollas (2003-2008) - this was the #1 culprit that caused all sorts of underhood noises. They were redesigned in the later 9th gen and 10th gen Corollas - but nothing to stop a serpentine belt tensioner from going bad.

Could also be the various accessories - like the bearing for one or more of the pulleys could be bad - something like the idler wheel (pulley that helps direct the serpentine belt) could be bad. I'm assuming that the mechanics tried running the car without the serpentine belt for a short time to diagnose the noise?

Valvetrain noise - not a whole lot you can do about that. Sometimes trying a different brand of motor oil will help.

Could it be a loose bumper or head light? Those can make a purring type noise when parked and vibrating.

I may have to try to go full synthetic, when I bought my car, the Toyota dealership was offering free oil changes for life so I may have to skip my free one (synthetic blend) and do a full synthetic myself and try that. It will be here in a couple weeks so I will let you know how that goes! It just worries me because I still owe 2 years on it!!

No doubt, with this sort of noise - pinpointing it could be tough. Fortunately, this doesn't seem to be a driveability or otherwise affect the longevity of the car - but doesn't mean that the noise is right or can't drive you bonkers as you are driving it.

Like you mentioned, it could be from the body of the car - loose or ill fitting body panels, exhaust heat shield touching the chassis or exhaust system, could be a damaged powertrain mount, etc.

Since you mentioned its temperature dependence and what is know on this generation - we initially steered you toward the most likely source of the noise. If those don't solve the noise - then you'll have to work your way outward to try and solve this noise.

Depending on your dealership - you might be able to get some relief from this NVH issue (Noise Vibration Harshness). Some dealerships extend that over some period of time - some as short as a year, some may go three years or more.

When I bought my 2009 Matrix - I had this weird high pitched squeaking/rubbing noise that only happened when the weather was cold and when I took off from a full stop to about 20 MPH. Was so pronouced on my long commutes to work, that I tempted to trade the car in for something else - bothered me that much. Dealership tried their best to pinpoint it - but couldn't find it. Through forums like this, I found out that it was likely the side airbag assembly in the front seat as the source. Options were to replace the seat or try to "lube" it. Dealership wouldn't cover the cost of seat replacement, just wanted to pull the airbag assembly out and lube it. I ended up replacing the seat on my dime (kept the other seat as a "spare" - fast forward almost 7 years, noise never returned!