Cars that spontaneously combust

By Tom and Ray Magliozzi King Features Syndicate
Saturday August 04, 2001

Dear Tom and Ray: 

You guys goofed! Your article on the cargo capacities of pickup trucks was completely wrong.  

A truck designated an F150 means the truck is rated for a half-ton of payload, not one and a half tons of payload, as you had said.  

An F250 is rated for a three-quarter-ton payload, not two and a half tons, as you stated. And an F350 means it's rated  

for one ton of payload. Please correct it before someone blows out his tires trying to carry too much weight. — Brian 

TOM: We goofed on our numbers, Brian. We both must have been passing brain stones that day. We know that traditionally, a truck with a designation of 150 (Ford) or 1500 (Chevy and Dodge) has been known as a "half-ton pickup," meaning that it has a payload capacity (the amount of weight it can carry, including passengers) of 1,000 pounds, or half a ton.  

The 250/2500 and 350/3500 pickups have traditionally carried three-quarter-ton and one-ton designations, respectively. 

RAY: But after we got your letter (and letters from about 10,000 other readers), we decided to do a little more research, and we discovered that the traditional designations are completely wrong, too. 

TOM: It turns out that the Ford F150, Chevy Silverado 1500 and Dodge Ram 1500 have payload capacities in the range of 1,500 to 2,000 pounds (if you want the exact numbers, you can look them up on our Web site, the Car Talk section of www.cars.com under "Model Reports").  

That means the 150/1500s are actually three-quarter and one-ton pickups! 

RAY: But wait, it gets even more confusing. The Ford F250, Chevy Silverado 2500 and Dodge Ram 2500 have payload capacities of between 3,000 and 4,700 pounds. So that's between one and a half tons and nearly two and a half tons. 

TOM: You still with us? Because the 350s and 3500s have payloads of 4,500 to almost 6,000 pounds, or between two and three tons. 

RAY: So the old notions of half-ton, three-quarter-ton and one-ton pickups no longer apply. And if you're planning to carry serious cargo, you really have to check out the specific payload capacity of the truck you're interested in. Even between different versions of the same truck, payload capacities can differ quite a bit. 

TOM: I still think Mercedes has the best and clearest payload designations. As we said in our previous article, they use designations like ML320 and ML430, which everybody can understand. It means those vehicles can carry 3.2 and 4.3 mothers-in-law, respectively.  


Dear Tom and Ray: 

Is it possible that my van (’94 Dodge Grand Caravan) burned on its own? Or was it vandalized? The whole engine compartment burned up. I hadn't driven it since 4 p.m., and at 3 a.m. my daughter woke me up to tell me that the front yard was on fire (it was actually my van in the driveway). Can a vehicle spontaneously combust? — Chaya 

RAY: Yes it can, Chaya. It's actually not spontaneous, but it would seem that way to you. 

TOM: Cars usually catch fire because a wire gets chafed somewhere. The initial damage happens most often during an accident or a subpar post-accident body repair.  

But it can also happen during regular engine repairs or when a misrouted wire harness has its insulation rubbed away by another part of the car. 

RAY: Once the bare wire is sufficiently exposed, it can short out against the car's body or frame and then start drawing current from your battery. 

TOM: And if it draws enough current over a long enough time, it can generate enough heat to make the wire's insulation smolder. And from there, it's a short leap to igniting surrounding parts, the fuel line and the front lawn. 

RAY: I'd say vandalism is very unlikely in this case, Chaya. Especially since the fire was in the engine compartment. I think it was just bad luck. 

TOM: So just be glad that you and your daughter were both unhurt and that the only casualty of the whole affair was a 1994 Caravan. I think that's what doctors would call "an extremely positive outcome."