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October 2010 Techline

Willie Worthy | Writer
Posted October 1, 2010

Ford Explorer transmission issues, Jeep CJ tires and more

Better Gearboxes and Lube For '99 Explorer?
Q. I own a '99 Ford Explorer with a pushrod 4.0L V-6 and auto transmission. My first question is what ATF would you recommend I use? I was thinking about a synthetic like Royal Purple, or I was thinking about using regular ATF with an additive like Lucas Oil's.

Would a shift kit extend the life of an automatic transmission when driven reasonably? Or should I go with a transmission programmer? I haven't gone wheeling with it, but I do tow a small four-wheel trailer every weekend that weighs about 2,000 pounds, and this just kills the performance of an already sluggish vehicle. The shift kit is something that this Explorer needs very badly, as it just shifts way too soon or it doesn't downshift when it needs to, and when you tow, it only magnifies those problems. But I don't want to put a shift kit in it; I'll be ripping the transmission out to get it rebuilt in a year anyway.

My second question: My transfer case is the auto four-wheel-drive junk. Is there any way I can swap it for a non-auto T-case, maybe out of an older Explorer or Ranger, or am I stuck with the auto?

Why does my engine temperature run so cold? In the summertime, it's not a problem, but in the winter it barely gets in the normal range, and that's with the radiator completely covered and with the hottest thermostat I can find. I still get heat out of the heater, but it really kills my mileage. I thought about installing an electric fan instead of the mechanical unit. Do you think that would help my cooling problem?
Jesse Leister

A. I don't have a lot of faith in oil additives, as they may or may not blend properly with the additives that are in a certain brand of ATF. However, I am a believer in synthetic ATF, especially on a vehicle that could encounter high transmission temperatures such as when being used off-road or when pulling a trailer. Be sure to select a Mercon-rated fluid. The better lubrication and the ability to operate at higher fluid temperatures is always a safety feature.

As to the shift kit, I will also say yes. I know B&M makes a good kit and I am sure an Internet search will turn up several more companies. Yes, it will help to extend the life of an automatic transmission, as firmer shifts mean less clutch slippage, which in turn reduces heat and clutch wear. The shift kit will not cause early wear to the transmission, but it will not fix a problem if the transmission does need to be rebuilt.

As to a transfer case swap, I am sure that with enough time and patience, it could be done; however, I don't have any information on such a swap. Perhaps an Internet search on the subject will bring up some information.

Running too cold? Now that is an unusual problem. Most people complain of their vehicles running too hot. My only thought on this is that you may have installed the thermostat in backwards, or that the pressure relief valve is not at the top of the engine. Okay, one more thought: Are you sure that the engine is not coming up to the proper temperature? Have you measured the coolant temp with another gauge and compared it to what the vehicle's gauge says? Do keep in mind, if you measure the temperature of the coolant at the radiator, it will be as much as 10 to 20 degrees lower than that within the engine. The easiest way to measure the temperature would be with a thermal gun. This way, all you have to do is point and shoot, and it will give you a fairly accurate comparison.

What could be the reason for your poor fuel mileage in the winter is the same reason the rest of us also complain. One, you may be letting your car idle a lot after start-up so it will be warm when you drive away, and secondly, in most parts of this country during the winter, the gasoline you're using is oxygenated, or in other words has ethanol added to it, which lowers emissions but will also reduce fuel mileage.

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