Today: The high cost of the Passat's sleek design.

Dear Car Talk

Dear Car Talk | Nov 01, 2006

Dear Tom and Ray:

You have undoubtedly noticed that some parts of the country got a lot of rain this past summer. Often, the result is large (sometimes deep) puddles, or flooding of entire sections of highway. Being the owner of a 2004 Passat, I was somewhat concerned when my wife informed me that a co-worker said that the engine of his Passat was ruined when he drove it through a standard puddle; it wasn't all that deep, just the sort of water puddle that anyone who has ever driven a car has driven through countless times (unless, of course, they live in Death Valley or something). Anyway, his car stalled and wouldn't restart. It turns out that the air intake is on the bottom of the engine and allowed water into the engine, which was damaged beyond repair. My wife and I did a quick check on the Internet, and indeed, a number of Passat and Jetta owners reported similar stories. How often have you encountered this issue, and what can us poor, unsuspecting Passat owners do to avoid the problem, aside from moving to Death Valley? Yours dryly -- Peter

RAY: It's not just Passats and Jettas, Peter. It's lots of cars -- especially sporty cars.

TOM: The problem is that if you want to keep the hood line low and sleek, like it is now on most cars, there's no room for the air intake on the top of the engine. So they run a duct to the air filter, which is often located behind a headlight or near a wheel well.

RAY: So, you end up with the air scoop a foot and a half off the ground, which is kind of dumb. But it's very widespread. And if water does get sucked up through the air intake, your engine will hydrolock and instantly be ruined.

TOM: And, while most people are smart enough to not drive through puddles that are a foot and a half deep, most people DON'T account for the wake created by their car or other cars.

RAY: Right. Even if you're the only one driving through a puddle, you create a wake, which radiates out to the edge of the puddle, and then ... radiates back in. So even if the puddle is only a foot deep, if you go too fast you could create a swell high enough to reach your air intake. And if other cars are going through the puddle, too, all bets are off.

TOM: So, what do you do? First, it's a good idea to know where your car's air intake is. If you can't identify it yourself, ask your mechanic to point it out to you. That way you'll know how high off the ground yours is. That's the first piece of information you should have.

RAY: If yours is near one of the wheel wells, you have to be extremely careful when going through serious puddles. The first step is to watch someone else go through it, to see how deep it actually is at its deepest point (I always let my brother go first).

TOM: If it's not too deep, proceed through very slowly, trying to not make a wake.

RAY: And if it IS too deep, or you don't know how deep it gets, you have two choices: One is not to go -- stop, back out and take another route.

TOM: The second choice is to cross your fingers and hope that if you don't make it, you can convince your insurance company that the puddle was an unavoidable road hazard, like a huge pothole or a log in the road that you couldn't avoid. Otherwise, you'll be taking out a home equity loan and buying a new engine.

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