Tom and Ray play detective on a cold case accident.

Dear Car Talk

Dear Car Talk | Feb 01, 1997

Dear Tom and Ray:

This is a "curiosity" question, as the incident happened 13 years ago when we had a teen at home. We bought him a 1977 Chevy truck, and except for accidentally driving on a major interstate the wrong way a couple of times, he took good care of it. One morning, while waiting at a Stop sign, a school bus rammed into the back of his truck. Except for the tail gate being bent and the tail light broken on his truck, there seemed to be no injuries or damage, so he exchanged information and went on his way. He got onto the interstate to go to school and less than two miles down the highway, a "pin" went through the engine block and destroyed the engine. This was less than 10 minutes after the accident.

We applied to the school insurance and were told that there was no way that the bus running into the back of the truck could cause this kind of damage to the engine. We had it towed to two trusted mechanics, and both told us the same thing. We paid a great deal of money for an engine salvaged from a wreck and he drove the truck for several more years. Is it possible that the bus accident could have caused the damage to his engine? And if so, how? We need to let this mystery go so we can stop discussing it. Thank you. -- Yvonne

RAY: You've been discussing this for 13 years, huh, Yvonne? Wow. Well, I agree with you. It's time for closure.

TOM: I take it a connecting rod broke off and pierced the engine block. Or, as we say in the business, you "threw a rod." And I can tell you with absolute certainty that there is no possible way that the bus accident had anything to do with your throwing a rod. I think.

RAY: Here's the only way they could be related. Engines usually throw rods when they're A) old, B) ready to throw a rod, and C) revved too high. So the first two preconditions may have already existed. Thirteen years ago would have been 1984, so the truck would have been 7 years old at the time. That's old enough, especially if it's been driven by a heavy-footed teen-ager. And being ready to throw a rod just means that one of the connecting rod bolts was stretched and ready to break anyway.

TOM: So that means all your son needed was pre-condition C. And here's how the bus accident created it. By the time your son and the bus driver had exchanged information, examined the vehicles, and walked around shaking their heads solemnly, your son would have been quite late for class, right? So when he got on the interstate, he did what? He floored it! And that's why these two unfortunate incidents took place in such close proximity to each other.

RAY: But rest assured, the truck would have thrown the rod eventually anyway. And the bus accident had absolutely nothing directly to do with it. So it's time to get on with your lives, Yvonne. It's been 13 years! This kid must be how old now -- 31? 32? It's time to let him out of his room and give him some dinner.

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