Low Whistle Noise After 5 miles

1999 Camry XLE runs perfectly. BUT, after start up and 5 miles at relatively slow speed get low, loud whistle noise. Noise will stop if stop acceleration or if accelerate more — for a short while. If turn off ignition and restart will begin in another 5 miles. Mechanics say evap canister; transmission; change transmission fluid. Any thoughts?

If the transmission fluid has over 25,000 miles (automatic transmission?) then you should change it, because it is due.  I doubt if it has anything to do with your noise, but it may help your transmission make it to 200,000 miles rather than 80,000.  You might want to try and new fuel cap, but well they are not expensive. 

Have you had any CEL (Check Engine Light)?  Do you have any problems filling the tank before the pump shuts off?  Are you in the habit of topping off the tank?

I have a light on that I have been told is the evap system. But the person who checked it said I need to have a new ‘canister’ installed – very expensive. I do keep the tank topped off, and I bought a new gas cap sometime back. But the cap wasn’t the $30+ one that Toyota wanted to sell me but a cheaper one. Wonder why the noise is a function of the engine warming up, since it takes about 5 miles for it to start?

And I also had been told that it may be a problem with the ‘vacuum’ hose. Whatever that means.

It sounds like this car has not been maintained as well as it should be. Is it up to date with all of the maintenance procedures listed in the Toyota Maintenance Schedule? If not, you have to begin with basic maintenance, rather than first trying to “cherry pick” one symptom to fix at a time.

My Corolla made a similar noise for several weeks before the alternator failed.