1999 Taurus making loud knocking sound under hood

[alxndra]

Today a noise started coming from underneath the hood of my 1999 Ford Taurus that sounded like a very loud lawnmower. It seems to do this both while driving and while idle, although the noise is significantly quieter while idle. The car has approximately 130K on it. The last few days before the loud noise started, it seems to accelerate by itself while at stop lights or any other time the car is not moving. I don't know if this is any relation to the now loud knocking under the hood. Any ideas what this noise could be?

[Willyum]

First of all, when anything like a "loud noise" starts coming from under the hood or anyplace else on a car, you should stop driving it if you don't want to completely destroy it. Open the hood and I.D. the source or have someone else do it.

[shorod]

Does it sound like a large exhaust leak? Have you checked the level and condition of the engine oil?

As mentioned above, you want to understand what the likely source is before driving the car further, unless you're looking for a forcing function to get a new vehicle.

-Rod