QDear 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

ATOM: So, let's look at what may 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. Anyway, Jennifer, these two tests will tell if your engine is damaged.

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.

Dear Tom and Ray:

I have a question about engine flushing. The other day, I went to my usual mechanic for my 3,000-mile oil change and tire rotation, and he tried to sell me on a "Bilstein Engine Flush." My question is, of course, is it worth it to get this flush, or am I just wasting $60? -- Terence

TOM: Actually, Terence, we've found that the number of mechanics who recommend engine flushes is directly proportional to the number who are making payments on an engine-flushing machine.

RAY: It's certainly not going to hurt your engine, Terence. But in the absence of any evidence that your engine is full of crud, I'm not sure it's really necessary.

TOM: An engine flush is a machine that removes your oil and runs a heated solvent through all of the places where the oil flows before adding back new oil. Supposedly, it removes any gunked-up oil and varnish that are clogging up your oil passages.

RAY: I have no doubt that it works. But if you've been changing your oil every 3,000 miles -- or even every 7,500 miles -- you really shouldn't have any gunked-up oil in there in the first place. It's necessary for the guy who bought the machine and needs to make his money back. But I'd say it's overkill for most people, Terence.

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(c)2004 by Tom and Ray Magliozzi

and Doug Berman