Piston Slap: "Oooooooo" Goes The Neon

TTAC Commentator Robstar writes:

My wife has a 2000 Neon we bought used with 125k. It just passed 50k miles in the 4 years we drove it. We have had no issues with this car so far, although the first owner (we are the third) replaced the tranny at 70k.

At about 35mph the engine starts making a loud “ooooooooo” sound (kind of like a deep throated turbo or a vacuum cleaner). There is no “windup” to this sound — it’s either on or off. It does not matter if you are accelerating hard or not. Since we do mostly highway driving, this sounds tends to blend into road noise once we are up to highway speeds. The engine is not short of oil (although it does need 1/2 qt every 1500 or so). We have driven the car for ~ 3k miles with no issues….but I’m getting nervous.

Any ideas what it could be? We will be taking the car to our independent mechanic this week for the oil change and will ask him to look at the sound, but it’s hard to get the car up to 35mph in the city around rush-hour (which is when I’d be there). Outside of this the car drives normally.

We’d like to keep this car at least another year, but I don’t want to leave my wife stranded on the highway somewhere. She has a 42 mile highway commute to work.

Sajeev answers:

There are several Chrysler transmission jokes I could throw in here, but perhaps discretion is the better part of valor.

There is a chance the Constant Velocity (CV) shafts leaving the differential are out of whack, though I suspect the torque converter is the problem. Maybe the Torque Converter Clutch (TCC) Solenoid isn’t engaging/disengaging correctly? I think a quick engine code scan and a road test by a savvy mechanic will clear up any confusion.

If it costs more than $300 to fix, I’d drive it into the ground and buy a safer vehicle sooner rather than later. Unless you really love the Neon (and there’s nothing wrong with that, trust me) you can find a more robust vehicle for not much more cheddar, and it’ll probably keep the family happier too.

(Send your queries to mehta@ttac.com)