Dear Tom and Ray: About two months ago, the Toyota dealer left a clamp off my radiator hose after servicing my car. After almost making it home (about 22 miles), the car began to steam. This was my first hint that the car was overheating. I pulled off the road and called for a tow truck. After examining the car, the dealer assured me that there was no damage, and provided a letter admitting responsibility. The engine seems to run louder than before; otherwise, I have not noticed a difference. How do I know if any damage was really done? -- Jennifer
Tom: It's sad, isn't it, that nobody believes car dealers? The dealer says it's fine, and her first question is, "How do I know if he's lying?"
Ray: Well, it's hard to know who to believe in this case, since the dealer has a vested interest in the outcome.
Tom: Oh, I'm not saying it's an inappropriate reaction. I'd do the same thing! I'm just saying it's sad. It's sad, that's all.
Ray: Well, sad as it might be, Jennifer, we have to give your dealer credit for admitting the mistake -- and even putting that in writing. That's a "stand-up" thing to do, and it gives him credibility, in my mind. It suggests to me that he's not trying to hide anything.
Tom: So, let's look at what might have happened, Jennifer. If the clamp was for one of the top radiator hoses, a small leak there could produce a lot of steam. Since the "hot engine" light on your dashboard didn't come on, it's entirely possible that all you lost was a small amount of coolant (as steam) and that the engine never even overheated. That would be the best-case scenario, and it's the one your dealer is describing.
Ray: On the other hand, if you just didn't notice that the overheating light was on, and you truly did lose much or all of your coolant through a lower hose, then you could have done some real damage.
Tom: How do you know? Well, the best way to ease your mind is to take it to another shop you trust, and ask the mechanics there to do two tests for you. One is a cylinder-head test, where they'll check to see if the head or head gasket has cracks in it. If an engine gets too hot -- especially if it repeatedly overheats and then cools down -- it can blow a head gasket, or even crack a head. Those are both expensive repairs.
Ray: The other test is an oil-pressure test. If an engine overheats badly enough, the main bearings and connecting-rod bearings can begin to melt and deform, and that would make it impossible to maintain proper oil pressure. That's a very serious problem, and it requires a new or rebuilt engine.
Tom: Incidentally, bad bearings could explain a loud engine, Jennifer. But don't be alarmed. It could also be your imagination. For instance, after I dropped my infant son on his head by accident years ago, my wife kept imagining that he wasn't the same. But he turned out fine. In fact, he's just like me.
Ray: Not very reassuring. Anyway, Jennifer, these two tests will tell all. If your engine is damaged (and I'm betting it's not), your dealer has taken responsibility and presumably will fix what needs to be fixed, at his expense.
Tom: And if your car checks out, I wouldn't hesitate to go back to this dealer. Every mechanic makes mistakes. It's whether you own up to them and take responsibility for them that makes you trustworthy or not. And this guy passed the test.
The "Car Talk" radio show can be heard locally on WBFO-FM 88.7 on Saturday mornings at 6 and 10 a.m.