Originally Posted by POWER STROKE 99
My Dad just bought a 1997 PSD, he and I were wondering should he drive with OD off in town and up hills, it has a SCT tuner does this adjust shift points, and how do you know when the TC locks up. BTW we are going to change the fluid and filter in the trans, should we take it to a shop and have them purge it all including the TC or do it our self ( I would rather do it myself) and which fluid is good.
I wouldn't turn OD off, except on certain big hills. You will get poorer fuel mileage with it off. Your applying extra braking to slow down when you cancel OD. That is the slow down decel you feel when canceling OD down hill in addition to gear 3 ratio. Braking is one reason you would manually select a gear. OD off will prevent hunting between 3-4, I agree. Gear 3 will be the highest gear. The 97 has a differant converter lock than a 99 up.
One way to know when TC locks on a 97 is watch the tach right after the 3 shift point. RPM will change, but our tachs aren't real sensitive. Maintaining a steady throttle should produce a tach needle flutter. Accelerating may cover it up as rpm's are increasing anyway. A full shift kit in a 97 can be set to make the lock up felt on apply.
An Original 97 TC will have a plug. You can change ATF. A Flush will push thru the cooler. You can use compressed air to, or use the cooler line off method to change ATF (for no TC plug).
If it has the small 2 row "U" OEM cooler, it's very undersize. I would consider replacing it if the Tranny is otherwise in good shape and adding a cooler line filter.
Mercon equivilent fluid, dual rated
Mercon and Mercon V, Dex-3, and any synthetic mercon/Dex3 rated fluid. I wouldn't recommend straight Mercon V if you do find it.