Automania/Repair & Maintenance

Auto Questions And Answers For Week 29 Year 2001

by Bob Hagin

Q. My wife and I purchased new a 1993 Cadillac Seville STS with the Northstar System. We have enjoyed the car, and have only 29,000 on it. Because of our limited driving (both retired), I have maintained the car on a time rather than a mileage basis. I have the oil changed at 1500 miles and the transmission serviced at 7500 miles. (The factory service recommendation is 15,000 miles). I also follow elapsed time for other services, as well; cooling, fuel filter, tires alignment, etc. What about the Northstar engine? It is advertised as being an engine needing no tune-up for 100,000 miles. The engine runs fine, but the gas mileage has become poorer with miles. With local driving, we get around 10 mpg and on monthly trips to the state capital, we get 14 to 18 mpg. Given our driving habits, when should we get consider a tune-up?

A. When you don't feel good or get seriously sick, you don't wait until your annual physical checkup comes around before you see a doctor. Use the same rationale in dealing with the "illnesses" of your Cadillac. In short-hop around-town driving, the engine usually doesn't get a chance to thoroughly warm up and this can lead to carbon buildup in the combustion chambers and varnish accumulation on the fuel injectors. There's a variety of ways that these problems can be rectified including chemical combustion chamber and fuel injector cleaning. A good start would be a static or dynamic compression check to make sure the cylinders are all operating well.

Q. Each spring, after storing my 1977 Dodge van for the winter, I restart it by dropping a quarter cup of gas and oil mix down the carburetor. This has worked great, though I now want to replace the van with a 1988 Dodge 2.0-liter Daytona with fuel injection. My problem is that I'm not sure how well the car will start in the spring. With fuel injection you can't introduce gas into the system very easily. I will need a specific procedure to prevent excessive cranking during start-up or will the electric fuel injection system start easily without draining the battery?

A. Your "new" car has an electric fuel pump as well as electronic fuel injection. If your battery is up to spinning the engine over, it's well up to the task of supplying power to the fuel pump so that it can put fuel into the injectors. Put 97-octane gas in the tank before you shut it down and run some fuel injector cleaner through the system 50 miles ahead of time. If the compression is good, there's no coolant leaks into the cylinders and the spark is good, you shouldn't have any trouble.

Q. I've had a recurring problem with my last three autos. All were Oldsmobiles. an '85 307 cid V8, an '88 307 cid V8 and a '96 V6. The problem is that the intake manifold gaskets developed leaks that result in a loss of antifreeze, leaving puddles on the ground. The '85 car leaked at 19,000 miles, the gaskets were replaced and it leaked again at 45,000 miles. The '88 car leaked at 24,000 miles, the gaskets were replaced and it leaked again at 54,000 miles. Now the '96 car recently developed a leak at 31,000 miles. Is this a design flaw or am I doing something wrong?

A. I assume you do the gasket replacements yourself but that you know that the nuts and bolts have to be tightened in a particular order and to a particular tightness measured with a torque wrench. Good quality gaskets make a difference too and the best now "slide" a bit under heat expansion rather than tear. Use as little antifreeze as possible. It has lower surface tension than water and finds leaks easier.