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Automania/Repair & Maintenance
AUTO QUESTIONS AND ANSWERS FOR WEEK 22
by Bob Hagin
Q. My boyfriend wants to become a mechanic but my dad says that cars are so well built and computerized that mechanics won't be needed in the future. Is this true?
A. Check a Toyota, Chevrolet or VW dealer's shop and you'll find mechanics replacing brakes, fixing blown head gaskets and overhauling engines just like the "old" days. The average mechanic is 50 and not enough young guys are coming in to replace us old timers as we retire.
Q. I bought my '91 Ford Escort new and it has a 1.9 liter engine, an automatic transmission. Since day one, the temp gauge has read on the low end of the normal range indicator. Over time, it would read lower and lower. Our local Ford dealer checked it, found nothing wrong but changed the thermostat anyway. The gauge still read low. In slow traffic during warm weather, the gauge will creep to the middle of the normal range then drop as traffic speeds up. The needle drops even further on downhill runs. I took it to the dealer again where another thermostat was installed but there was no change. As a former aircraft engine mechanic I know that constantly varying temperatures are detrimental to the operation of an engine. I suspect that the cooling system sensing devices are at fault. I asked the Ford mechanic if I could get a different indicating system but he said it was impossible since the device is magnetic.
A. I've never really trusted electrical coolant temp gauges so I use a "master" gauge to give me accurate readings. It's a cheap mechanical temperature gauge that consists of a two-inch dial that reads from 0 to 250 degrees F. A sealed tube filled with ether (I think) connects it to a sensing bulb with a pipe-thread adaptor that allows it to be screwed into an applicable hole in the engine block. Sometimes I've had to use some kind of an extra brass adapter to get it into place but I've always been able to get it operational. Jerry-rig a similar system on your Ford, secure it under the hood, go for a ride then stop and take a reading. This will tell you if your engine is truly running cold or if the gauge system is as fault. From there you can either install a hotter thermostat or run down the electrical problem with a volt/ohm meter.
Q. We use our 1989 Volkswagen Fox as a second car. It has close to 100,000 miles on it and has given pretty good service although we had to have the cylinder head gasket replaced about a year ago. It was diagnosed as a head gasket but we had a valve job done at the same time. At the time the mechanic told us that it might begin to use more oil since the piston rings might not be as well sealed as the valves. He was right but the increase in oil usage has only dropped the miles per quart to one every 2500 miles. Before that, it didn't use any oil at all between changes. Now the car has a very erratic miss that doesn't seem related to either engine or road speed so much as when driving over a rough road. The mechanic who did the valve job can't find the problem.
A. Erratic misses, especially when they're related to a condition encountered on the road, are very tough to find since the condition is almost impossible to duplicate in the shop. A diagnostic machine may not find them so it's up to a sharp-eyed, experienced mechanic. As a guess, I'd say that there was something that has worked loose after the top end was dismantled for the valve job. It might be something as simple as an air or vacuum hose that has become loose at its connection or maybe rubbed a small hole in itself by chafing against a metallic brace or bracket. The auxiliary air regulator hose to the intake manifold may have developed a hole, for instance, or an ignition wire may have developed a bare spot that periodically shorts out.
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