•Q. I had a spark plug blow out. The tip of the spark plug fell into the engine. Will that hurt it if I can’t fish it out? I drained my oil, but it didn’t come out, and I am trying to avoid taking the head apart. Thanks for any advice.•

TOM: Well, like the goldfish my brother once swallowed, these things all come out eventually.

RAY: Actually, are you sure it went into the engine? If the spark plug blew out because it was improperly tightened, the tip also could have blown out. It could have hit the underside of the hood and dropped to the ground.

TOM: That may be why you can’t find it – it isn’t in there!

RAY: If you’re pretty sure it fell in there, then I’d look for a shop with a borescope. A borescope is just like the thing they used for your last colonoscopy, except it’s for cars. It allows the mechanic to snake an optical tube through a small opening – in this case, the spark-plug hole – and look inside an otherwise mysterious, dark space.

TOM: If he sees the piece in there, he can try any creative way he can think of to remove it. A magnet won’t help you, in this case, because of the particular metals involved.

RAY: But at times, we’ve been able to remove foreign objects from cylinders using a coat hanger with a blob of silicone adhesive on the end.

TOM: Or sometimes, by blowing compressed air into the cylinder, you can force the piece out.

RAY: But if he can’t get it out using whatever tools are at his disposal, then you’ve got some decisions to make.

TOM: If the piece is clearly metallic, like the electrode, it’s likely to do some damage to a valve if you run the car. In that case, it makes sense to remove the head and get the thing out.

RAY: Right. Otherwise, you’ll end up paying to have the head removed AND paying for a valve job.

TOM: If it’s something that’s small and appears destructible, like a piece of porcelain, then you can start up the car, and let the piston crush it and send the remnants out the tailpipe (see goldfish, above).

RAY: And if you can’t find it – so you aren’t even certain what, if anything, is in there – then you probably need to take a chance and try starting up the car.

TOM: I’d let your mechanic do this. His ear is better-tuned to expensive-sounding engine noises than yours is.

RAY: Right. He’s bred to home right in on people who need rebuilds.

TOM: What he’ll do, with an assistant, is start the engine. If it sounds normal, then he’ll know that either the piece was never in there, or it was something that got quickly chewed up and spit out by the cylinder.

RAY: If it makes loud, frightening noises, he’ll shut it off immediately to limit any damage, then he’ll run a credit check on you and, if you pass, give you an estimate for some serious engine work.

TOM: Good luck.

•Q. My husband’s car is a 2005 Prius with about 130,000 miles. Our local Toyota dealership told him that the hybrid battery needs to be replaced and that it is no longer under warranty. They quoted him a price of $3,200 to replace it, including labor. I’ve researched and found a couple of sources for aftermarket batteries at a much-reduced price, but I’m not sure how to figure out where we can have an aftermarket battery put in. We checked with the garage we usually use, and they don’t do it. Any thoughts?•

TOM: You’d have to ask around to find an independent shop that has the confidence to install an aftermarket battery for you – preferably one that’s done it before!

RAY: You should try to find a Prius owners group in your area by looking online. That may lead you to the one or two shops in your area that do this kind of work.

TOM: But I’d urge caution at this point. It’s true, you will save many hundreds of dollars with a “remanufactured” Prius battery, but I just don’t know enough about their lifespan, personally, to endorse them yet.

RAY: They might be fine. They might be every bit as good as the original Toyota battery, or even better. But what if your replacement lasts only slightly longer than the warranty they give you? What if they warranty the battery but not the labor to replace it? What if the installer makes a mistake that leads to a small marshmallow roast in your garage?

TOM: Until more people have more cumulative experience with these aftermarket batteries, we don’t feel we have enough information to say they’re just as good as the original.

RAY: I mean, if you’re planning to keep the car only for another year, then sure, save the money, take a small risk and use an aftermarket battery. You’ll probably be fine. Plus, you’ll help with our research!

TOM: But if you’re thinking about keeping this car for another three, four or five years, I’d lean toward a factory battery right now.

RAY: If you do go with the Toyota battery, call around for pricing on those, too, and don’t be afraid to negotiate. Dealership prices may vary, and since it’s the kind of thing you do once in a vehicle’s lifetime, it might be worth it to drive a little farther from home to save a few hundred bucks.

TOM: And by the time your next Prius (your 2021 model) needs a replacement battery, I’m sure we’ll have much better information for you.

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