Q.

I bought my used 2000 Nissan Xterra almost three years ago. Every once in a while it did this weird thing where all the dashboard functions froze. The tachometer, speedometer, temperature gauge, fuel gauge and digital odometer all stopped working. The odometer would, at first, be random nonsense. Then it would gradually fade away. It seemed to be happening when the car got hot, so I used my windshield cover and parked it in the shade most of the time, and it stopped happening. Then, after about two years, this past winter it started happening again. Now it's happening frequently. When I went for an oil change, I asked them to check the battery, which they said is fine. On the way home from the oil change, it happened three times. It happened twice the next day, and then everything stayed frozen until I parked the car. Usually the gauges would all freeze in position, but the last time it happened, they went to zero - as if the car were shut off. Is this dangerous? Is it some sort of short in the electrical system in the dashboard or something? Should I get it fixed? And will it be expensive? Thanks.

TOM: Yes, yes, yes and yes.

RAY: It's not dangerous in the sense that your car is going to catch fire this afternoon (I don't think). But it's dangerous in that if there is a real mechanical emergency - like low oil pressure or overheating - you might not know about it because your dashboard gauges and warning lights don't work. And that could cause you to cook your engine.

TOM: Plus, it's not a great idea to drive without knowing how fast you're going.

RAY: It sounds like you have a bad instrument cluster.

TOM: Sometimes the printed circuit boards in these instrument clusters fail. The problem often starts out intermittently because these tiny broken connections on the circuit board can be affected by heat or by hitting bumps.

RAY: Sometimes the circuit board can be repaired. We have a place that we send them out to. If they can find the bad connection, they can solder it and send it back to us.

TOM: Of course, that takes time, and the car will be in the shop with the dashboard apart while we wait and see if the board can be fixed - and then sent back.

RAY: But the alternative is getting your dealer to put in a whole new instrument cluster for you. That'll probably cost you close to $1,000.

TOM: You can try getting one at a junkyard. But you'll still have to pay for the labor, and there's a chance that your "new" one will have the same problem as the old one - or develop it on your way home. And would that frost you!

RAY: If you're determined not to spend any money, if you have a portable GPS unit you can use that to tell you your speed. But that small screen is hard to read. And, like I said, if your oil pressure drops or the engine overheats and your dashboard warning lights don't work, your engine would be toast.

TOM: So, see if you can find a shop that can try to help you repair your circuit board first.

RAY: If that doesn't work, and if the car is otherwise in good shape and you plan on keeping it for another year or two, then the best thing to do is bite the bullet and replace the cluster. Good luck.

Q.

If a tin of sardines is attached to the exhaust manifold of a 1993 Ford F-150 with a pair of large radiator clamps, will the heat cause the salt water in the can to boil and the tin to explode? If so, how many miles of highway driving would be necessary? Would the resulting explosion be loud enough to be heard in the cab? Would the explosion cause any damage to the engine or engine compartment? Can the smell of hot sardines ever be washed away? Neither Siri nor Google seems to know the answers to these questions, but I thought a pair of MIT-trained auto mechanics might. Just curious.

TOM: I smell a prank in the works. "Smell" being the operative word.

RAY: The answers to your questions are yes, five, yes, no and no.

TOM: I don't know that the tin would explode, but the exhaust manifold would heat the water enough to probably burst a seam in the can.

RAY: And since the exhaust manifold gets up to about 600 degrees F, it wouldn't take very long. You even could heat up the sardines that come packed in extra-virgin olive oil if you wanted to get fancy.

TOM: No mechanical damage would be caused. We've never done a "sardine job" on a car, that I'm aware of. But it would spray that smell all over the engine. And for a long time thereafter, every time the engine heated up and the ventilation system was in use, sardine odor would waft into the passenger compartment.

RAY: It might not last forever - maybe just 15 or 20 years.

TOM: This is a dastardly thing to do. It's really long-lasting and unpleasant. I think I'm going to try it on my brother's car.

RAY: Well, I'd think carefully about the revenge you're going to invite before moving forward with Operation Sardine Can. But if we get a letter in a few weeks asking how to get sardine odor out of an engine compartment, we'll know what you decided.

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