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Automania/Repair & Maintenance
AUTO QUESTIONS AND ANSWERS FOR WEEK 32
by Bob Hagin
Q. I have a 1993 Toyota Camry with a V6 engine. It now has about 65,000 miles on it. It is used mainly for commuting (about six miles one way). I started to notice the engine overheating about two years ago. I brought it to the local Toyota dealer twice and they changed the thermostat both times without any improvement whatsoever. Thinking back, I believe that the thermostat did not have anything to do with the problem. It was simply due to low coolant level from over-consumption. Supposedly, the dealer checked for a leak and also the cap pressure. In desperation, I changed the radiator cap without any improvement. The car does not have any obvious leakage of the coolant. However it now consumes about two-thirds of the fluid between the fill and low marks on the radiator reservoir tank every week. As long as I keep adding to the coolant in the reservoir, the engine will not overheat. What are the signs of a blown head gasket? Shall I go to an independent mechanic?
A. The classic signs of a leaking or blown head gasket are that the engine overheats and system loses coolant, usually out the tail pipe while the vehicle is running. A thermostat in the system restricts the flow of coolant through the engine until a predetermined coolant temperature is achieved and then the main passage is opened up. Even then, the flow is somewhat restricted. A blown head gasket can best be identified by using an infrared analyzer to test for hydrocarbons and carbon monoxide in the cooling system. Before you have major work done, have a mechanic clean the engine and then pressurize the radiator with a hand pump to 17 pounds per square inch. It should hold the pressure indefinitely and if it doesn't, the coolant is leaking somewhere, possibly into a combustion chamber, the oil pan or onto the ground.
Q. Our Mercury Villager has a Nissan V6 engine in it. This model year had a modification which supposedly extended the life of the timing belt. Traditionally, timing belts are changed at 70,000 miles but the manual states that this belt change should take place at 105,000 miles. While I was away, the local Mercury dealership attempted to convince my wife to replace the belt as "..it was due to fail at any time." She called me and I had her show the dealership the manual which reflects the 105,000 change. They replied that it was her business when she changed the belt, but their advice still stands and they expressed that she risked breaking down at any time. I checked all my normal sources, talked to other Mercury service techs, and checked online and can find no recalls on the timing belt, no complaints from other owners with the same problems, etc. Are you aware of any problems with this belt that we should change it before the 105,000 miles stated in the manual?
A. I haven't had any reports of premature timing belt failures on that Nissan V6 engine but I called a friend at a Nissan shop. Like the Mercury manual, the Nissan recommendation is to change it at 105,000 miles but he states that his shop recommends the belt be changed at 90,000 miles, giving the customer a 15,000-mile margin of safety. That's a comfortable margin, but I think that 35,000 miles early is excessive.
Q. I'm interested in cars and want to get into the hobby, but I'm not in a position to buy collector's cars. I'm still in high school and I'd like to get into collecting auto-related memorabilia. How can I get started without spending a lot of money?
A. Your first step is to buy a current issue of Hemmings Motor News and peruse the upcoming swap meets and shows you can get to. Hemmings will also give you an idea of what stuff there is to collect (hub caps, literature, models, etc.) and kindred spirits you could hook up with. I hope you have access to a car. Some of those Texas meets are spread out.
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