I own a 2002 mercury mountain 4wd runs great and its clean. I just reached 85,000 miles what do I do to maintain good running. and also the check engine light is on.
It's good that you're looking at ways to keep your car running awhile longer. Too many people don't think about maintaining their autos and don't consider just how much the vehicle is worth to them until it's too late. They ignore common sense in auto maintenance until they find themselves having to buy a new car to replace a car that they viewed as not worth very much. Only problem is they are now paying several hundred dollars a month more to get the same basic transportation. Of course, I don't have to tell you this since you're here considering taking preventive maintenance steps, but, maybe, there is someone else reading this answer who will now think twice about letting maintenance slide until something breaks or wears out from lack of maintenance.
To answer your question: A check in your car's maintenance guide will show you what is recommended by the manufacturer. Of course, some feel the service intervals and the things recommended are a little over the top. I guess the factory's view is they had rather someone service a car a little too often than not enough. I'm going to assume you haven't really done alot of preventive maintenance to your car and now have decided, because of the current economy, to increase your chances of getting some more out of it, extending it's life. At 85,000mi I would have the cooling system flushed, the automatic transmission fluid changed, and have the spark plugs replaced.
1. If the cooling system hasn't been flushed in the last 3 or so years, it's a good idea to do it now. Expect to spend $50-60 or more at a service center, or have a local general auto mechanic do it for some less than that price. The general mechanic may not have a method of power-flushing the system and you may opt to go the more expensive route for that reason since anti-freeze residue builds up in the cooling system and can eventually cause the the engine to overheat. Although that is not a frequent problem, I just feel better about it knowing I did what I could to maintain an effective cooling system.
2. The automatic transmission fluid should be changed probably at no more than 60,000mi, but 85,000 is not too late to avoid problems. I would take it to one of the quick-change oil-changing centers, such as Valvoline, that has a machine that will actually change "all" the fluid in the trans. Unlike the usual method of servicing the trans where the drain pan is removed and only about 1/3 of the fluid changed, I would go with the method of changing all the fluid. One possible negative to using the fluid-changing machine is that it doesn't allow the filter, which is found in the drain pan, to be changed since the machine changes the fluid while the car is running, using the transmission's pump to completely change all the fluid. If your present transmission fluid is "clear", with no cloudiness, I wouldn't be concerned about changing the filter since it is doing it's job and hasn't had to filter out cloudy fluid caused by worn parts. Of course, you could drain the pan, change the filter and then add enough fluid back into the trans. in order to get it to the service center where you will then have all the fluid changed, but you're really just wasting fluid, and paying two people to do two jobs. Given the choice between changing all the fluid or changing only part off the fluid when changing the filter, I would go the route of changing all the fluid. Expect to pay $60-75. for the general mechanic to do the filter/fluid change, and expect the service center to charge about $75. It's kind of expensive for what they do and the time it takes, but most people had rather not go thru the hassle, grease, grime to do it themselves - if they knew how.
3. Today's electronic ignition system is very kind to spark plugs, unlike the old days when changing spark plugs was about as often as changing the engine's air filter. Today, an engine can run up to 100,000mi. or more on a set of spark plugs, however, you should expect a little less engine efficiency because of the older spark plugs than with new ones. Go ahead, change them before something like this is forgotten forever until after many miles you suddenly have engine stumbling, poor fuel mileage, and hesitation caused by badly worn spark plugs that should have been replaced long ago. Expect to pay the general neighborhood mechanic $35. plus cost of plugs, and expect to pay the dealer as much as $100. if they are difficult to get to and the manufacturer recommends a premium spark plug. I paid $99. for my spark plug job, but the mfr. recommended a special multi-electrode spark plug and the mechanic had to just about "stand on his head" to change the ones on the back side of the engine in a very confined area.
There are other more "routine" service items on your car so it helps to use a quick-change center where most items are carefully checked by it's staff. I'm pretty good at doing my auto repairs having been raised in my dad's garage years ago, but even I use the quick-change centers because they are thorough and I'm at a point in life where I just don't feel like getting a ton of grease under my fingernails. Happy Motoring!
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