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Automania/Repair & Maintenance
Auto Questions And Answers For Week 37 Year 2001
by Bob Hagin
Q. At nearly 60, I've been doing minor tune-ups, including changing spark plugs, for about 40 years. In all that time, I've never had a spark plug actually come apart while trying to remove them from the engine but I guess that there's a first time for everything. In 1998, at 30,000 miles, I replaced the spark plugs on our '96 Nissan Quest van with a new set. I "snugged" them down using a standard foot-long ratchet wrench with no more force than usual. At 30,000 miles and about three years later, I tried to replace them, using the same ratchet. The first four plugs came out whole, but on the fifth plug, the two-part steel fitting on the bottom of the plug separated, leaving the threaded part stuck in the cylinder head. It took a mechanic an hour- and-a-half and three tries using several different versions of an Easy-Out to get it dislodged, and it cost me $100 for his effort. Is this becoming a common thing with spark plugs? The mechanic and others involved with cars and car repairs say they've never seen anything like this. Should I stick with some other brand of spark plug? I've always been under the assumption that the steel part of the plug was one piece.
A. I've never seen a modern spark plug come apart like that but in the early days, some spark plugs were two-piece and could be unscrewed so that the porcelain could be cleaned with a wire brush. The only problem I've seen in modern plugs is when they're reinstalled with an air wrench. The shock of the plug bottoming can knock loose the porcelain around the center electrode. The correct way to install a spark plug in your aluminum head is to do it on a cold engine, coat the plug threads with a non-seize paste and use a torque wrench set at around 15 to 18 pound/feet. I had to extract an uncoated plug recently and due to some coolant seepage, it came out hard all the way. Fortunately, the aluminum threads stayed in the head.
Q. Where can I finds the value - if any - of a 1980 BMW 320i. It has always been garage-kept. The body condition is excellent and the interior is very clean. It could be made to run. I would like to sell it but I have no idea if it has any value.
A. Your BMW isn't old enough to be "old" and collectible nor exotic enough to be a potential classic like the 633CSi coupe of the same year as your 320i. Your comment that "it could be made to run" is going to put off buyers except the dyed-in-the-wool BMW enthusiasts since BMW parts are expensive. If you can get it running for a reasonable amount, it would bring up the value but the current price guides say a good one is only worth about $2000. If this isn't viable, your best bet might be to call around for a dismantling yard that specializes in imported, European or BMW cars.
Q. What is the purpose of wheel bearings? How does the health of the wheel bearings affect the wheel? How long do the bearings last? What can the vehicle owner do to preserve the life of the bearings? I own a 1970 Olds Cutlass 4-door sedan and was recently advised that to replace the bearings would cost about $1500. I realize that the amount is rather high to be spent on an old vehicle, however that amount is more affordable than the cost of a new or used vehicle having similar quality, i.e. a 350 engine, like-new interior and exterior.
A. Your Olds rolls on bearings that carries the weight of the car. They are either permanently packed in grease or have to be removed and repacked periodically. Service frequency can be found in you owner's manual. A question: what lead your service advisor to recommend replacing your wheel bearings? The sign of bad wheel bearings, either front or rear, is that they get noisy. Have another shop check them out. I've never seen all four of them go bad at once.
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