Towing Can Damage the Transmission
Question: I have a 1983 Nissan Sentra station wagon with a 5-speed manual transmission. I would like to know whether I can tow it in the conventional manner with all four wheels on the ground or whether I have to use a dolly to lift the two front wheels off the ground. I have talked to several mechanics, who have given me conflicting advice. I am somewhat disabled and it would be a problem for me to use the dolly. Is it safe to not use one?--F.H.B.
Answer: You could cause serious transmission damage, costing hundreds of dollars in repairs, by not using a dolly. Your owner’s manual recommends towing the car not more than 50 miles with all four wheels on the ground.
The reason is that not all of the gear shafts in the transmission rotate when it is in neutral, which will prevent them from splashing through the transmission oil. While that is safe for short towing distances, the gears and bearings may eventually run dry and be damaged.
It is also not practical to drop the drive shafts from the transmission, because they are inserted into the transaxle system with oil seals, unlike the old rear-wheel drive shafts that you could easily drop by removing no more than four small bolts.
Unfortunately, there probably aren’t many alternatives to putting the front wheels on a dolly. Generally, a car can be driven up a ramp onto a dolly. Then, you simply need to chain down the wheels to the dolly. Even though you need to do some crawling around under the car, the conventional method of towing a car isn’t a piece of cake either. You often must hook up safety chains, which also requires some real grunt work.
Q: I have a mid-1980s fuel-injected Chevrolet that is prone to injector fouling. I have heard that there is a new cleaning substance that is more effective and economical than the older methods. Can you tell me anything about it?--I.B.
A: The Minnesota Mining & Manufacturing Co. has developed a one-step system that cleans dirty injectors with a concentrated, high-octane cleaning solvent. 3M claims that cleaning dirty fuel injectors can solve 92% of injector-system problems. In the past, clogged fuel injectors often had to be replaced at a cost of $70 to $100 per cylinder.
While the new system probably will not work in every case, it should allow the restoration of the fuel-injection system without a major overhaul. While other solvent cleaning systems have been used in the past, 3M claims its system never allows solvents to enter the fuel tank or line, where they could damage linings.
The new procedure takes only 15 minutes; however, we do not suggest it as a do-it-yourself project. 3M advises that the procedure should be performed by a qualified fuel-system mechanic.
The injectors become fouled when dirt in gasoline blocks the tiny nozzle tip of the injector, which is designed to squirt minute quantities of gasoline into the intake manifold of the engine. The opening on a typical injector is about 1/10,000th of an inch in diameter, so it doesn’t take much to clog it. The problem is worse in hot climates and in stop-and-go city driving.
Improved gasolines have also helped prevent fuel-injector fouling. Most major gasoline brands now contain detergents that help prevent blockages from forming. But the detergents haven’t fully solved the problem.
Q: You recently wrote a column on car fires. I would like to suggest that the first thing a motorist should do when a car fire occurs is to shut off the engine. Many newer cars with fuel injection systems have electric fuel pumps that continue to supply explosive gasoline to an engine fire until the ignition switch is turned off.--C.M.
A: That’s sound and easy-to-follow advice. So often in an emergency, people forget not only to shut off their engines but to shift their transmissions into park or set their hand brakes. They are in such a rush that their carelessness often compounds damage that would be relatively minor. Nothing is worse than having a minor accident and watching the car roll or drive itself away because a motorist forgot to put on the parking brake.
Q: Every time I take my Toyota Tercel in for service, my garage wants to replace my spark plugs, which is about every 10,000 miles. I thought the new electronic ignition systems were capable of going 30,000 miles on a set of plugs. What gives?--C.A.
A: Some mechanics will change spark plugs far more often than recommended by the manufacturer and probably more than is really necessary. In the older non-electronic ignition systems, a set of plugs generally was needed every 10,000 miles.
While 30,000 miles on a set of plugs may be stretching them a bit, if you need new plugs every 10,000 miles, you may have some other type of a problem, such as oil fouling or carbon fouling of the tips.
Next time, ask to see your old plugs. They should have a light brown to grayish-tan color and have minimal wear on the electrode in the center of the plug. If they have a slick black coating, you may have oil leaking into the cylinders. If they have a sooty texture, you could have an over-rich fuel mixture. A lot of other problems can reveal themselves on plugs; an expert should be able to help you read your plugs correctly.
Q: I have purchased a new car and am wondering whether manufacturers still use a special oil to break in the engine. I plan to change my oil more frequently than suggested in the owner’s manual, but I don’t want to do it on the first change if there is special oil in the engine.--P.R.
A: There is no such thing as break-in oil any longer, according to Norm Hudecki, an oil expert at Valvoline Oil. The oil you buy at any store is the same oil that the manufacturers use in the first filling of the engine. You just want to make sure to buy the top-rated SG oil and the correct weight recommended by the manufacturer.
