[mbtoloczko]

Originally posted by dcarrb


Actually, unless you live in the tropics, you WANT it in series, as Joe posted. Like this: transmission> external filter> supplemental cooler> in-radiator (stock) cooler> transmission. When it's truly cold, the stock cooler will warm the ATF on its way back to the tranny. With an add-on cooler bypassing the stock cooler altogether, the ATF may not warm sufficiently to allow torque converter lockup in cold weather.

In short, the function of the stock cooler is not so much to literally "cool" the transmission fluid as it is to maintain its temperature within normal operating range.

As I said, Capuano, opinions are apt to vary on matters where there are no absolutes. Confused yet?

dcb

I can tell you from first hand experience that if the external ATF cooler is in series with the radiator cooler (which can both cool and warm the ATF depending on the ATF temp), the ATF will not warm up enough to consistently lock the TC on the highway in cold weather. With my setup which had the external cooler in series with the radiator cooler, any time the temperature dropped below 45F, the TC would not stay locked on the highway. When the TC was unlocked, the ATF would warm up enough to allow the TC to lock. But once the TC locked, the ATF would quickly cool down, and the TC would unlock again. The cycle would just repeat endlessly. And if it got cold enough, the TC would never lock at all. My final solution before I switched over to the 5MT was to install a by-pass thermostat on the ATF line going to/from the external cooler. That actually worked great in the wintertime. The combination of the thermostat and the external cooler would regulate the ATF temperature right at 150F.