Question: I was recently told by the person installing tires on my car that it sounded as though it needed a new water pump. With the car driving perfectly, I wasn't sure how to accept this recommendation and declined to have it looked at further.I'm now wondering — could this fellow be that intuitive, or could this have been a ploy to sell me something that might not be needed? Is there a proper way to determine if my water pump is OK?Answer: All water-cooled passenger car and truck engines use a water pump to circulate coolant throughout the engine, radiator and heater core. On older and many current engines, the water pump is driven by one of the accessory drive belts and is visible at the front of the engine.On overhead camshaft engines, the water pump may be driven by the timing belt and concealed from view beneath a plastic cover.A typical water pump consists of a metal housing, a shaft with the belt drive hub at one end and a fan-like impeller at the other. A sturdy, permanently lubricated bearing supports the shaft, and a seal prevents coolant from leaking out of the pump body. The water pump is securely bolted to the front of the engine, using a gasket or O-ring to seal the connection.There are three things that can go wrong with a water pump; bearing wear/failure, seal leakage and erosion of the impeller. Should the bearing wear out, this usually results in a whirring/growling noise — a distinctive sound familiar to many who have fixed their share of cars. On an accessible water pump, one may also find looseness in the bearing, evident by wiggling the drive pulley or radiator cooling fan. A failing bearing, in the case of the hidden, timing belt driven water pump, could become a huge problem if the bearing seizes.This could strip cogs from the timing belt, or break it, resulting in some very expensive crashed valves. Regardless of the type of water pump, a loose or noisy bearing requires urgent attention. Removing the belt and turning a water pump by hand will usually confirm suspected bearing roughnessWater pumps are also known to leak coolant from a failed seal. Oddly, this can happen with a perfectly quiet and tight bearing or a loose one, and the leakage can occur at unpredictable times; engine cold, hot, parked or running. It's a sure bet that leakage will soon follow, should a noisy/loose bearing be detected.An eroded impeller can sometimes occur, usually the result of insufficient cooling system maintenance. This can be a sneaky situation, as the pump is quiet and leak free. The only symptom is insufficient engine cooling. Removal and inspection of the pump is the only sure way to verify this condition.My hunch is your tire tech knows his/her stuff, and you should have this possible problem researched further. The expense of a severely overheated or internally damaged engine can be huge, and is almost always avoidable.

Question: I'm hoping you can help me with a problem that's similar to one recently printed. Occasionally my car won't start. It makes no sound whatsoever when I turn the key. Later in the day, or

maybe just a few minutes later, it starts right up perfectly. Jumping the battery doesn't help either, when it's not wanting to start. From reading your column I've learned a repair shop will have a hard time fixing this unless it happens while it's there. And since it has only

happened three or four times in the last couple of months, I can't be without the car for a long time waiting for it to act up for them. What should I do?Answer: You've made this easy for both of us by explaining the symptoms so clearly.Since the car starts well, without assistance after each no-crank event, we can rule out the battery, charging system or key-off battery drain. This leaves a possible faulty starter, loose battery cable, or starter control circuit. If the car has an immobilizer (anti-theft) system, this may also be the culprit.Your starter is by far the most powerful electrical device in the car. Engaging such a device requires a very robust electrical switch which is mounted on the starter, or in the case of older Ford vehicles, on the inner fender.This solenoid or relay receives a signal (voltage) from the ignition switch, makes a loud click, and delivers power to the starter. The solenoid or relay has two very large cable connections (the in and out of its massive switch — one connects to the battery, the other to the starter), and a small wire connection (the command signal from the ignition switch).As you turn the ignition switch to the crank position, voltage is sent to second switch, either near the clutch pedal (manual transmission) or gear selector (automatic transmission).If the clutch is depressed, or the shifter is in park or neutral, voltage continues to the starter solenoid or relay terminal. In many vehicles this circuit may turn on a small relay (it makes a small click), which in turn sends a signal to the starter solenoid or relay.If the car has an immobilizer system, it may intervene by denying (small) relay operation. Have you tried jiggling the shifter or clutch pedal when it fails to start? If this corrects the problem, that switch is faulty.Let's continue by firmly wiggling the battery cable connections.If they're loose or appear corroded, this may be the problem. If not, next locate the small wire connection at the starter solenoid or relay. On some vehicles this may be easy to access, on others can be difficult.Next time the starter fails to crank, this is the place to test. An inexpensive 12V test light or voltmeter will quickly verify the starter control circuit as a helper turns the key. If voltage successfully arrives at this location, the control circuit is good and the starter, solenoid, or relay is the likely culprit (they're an integrated unit, unless it's an older Ford).If a dim test light or no/low voltage is noted, the fault lies in the starter control circuit. The most likely causes would be the ignition, clutch or shifter switch, or if used, the small relay.If there's no voltage at the solenoid terminal, and the car is immobilizer equipped, the fault may be with it.Narrowing the search with this simple test will greatly increase the odds of a single, effective repair. Otherwise it may be become an expensive guessing game.Brad Bergholdt is an automotive technology instructor at Evergreen Valley College in San Jose. E-mail under-the-hood@earthlink.net. He cannot make personal replies.