Low gear appears to be gone..

Chum lee wrote:
Although I am not a Master Tech by trade (I am an engineer) I have owned and changed the ATF in many cars/trucks. Virtually EVERY factory service manual I've read that recommends one says when changing the ATF to DROP THE PAN AND CLEAN OUT THE DEBRIS on the bottom, on the magnet (if there is one) and clean/replace the filter. That is far more important than flushing every last drop of used ATF out of the system.

I don't care how many times you flush the fluid, the debris on the bottom of the pan stays there until someone physically drops the pan and removes it. It simply doesn't come out with flushing alone.

Think of a torque converter as a 10 hp centrifugal ATF filter. Have you ever looked at the debris inside a torque converter when a rebuild shop cuts the shell apart? Its the same stuff that is on the bottom of the pan. ATF is different from engine oil in that it has few if any added dispersants mixed in the formula. The engineers WANT the particulates to drop out of the fluid in ATF whereas with engine oil not necessarily so. Also, ATF hopefully isn't subject to contamination from combustion byproducts whereas engine oil is.

To the OP, hopefully an ATF flush will solve your problem but I wouldn't bet on it. You've been given some good diagnostic options by others. Good luck.

Chum lee

I'm paranoid about flushing transmissions and especially if they're old with miles. Had a jeep for 19yrs and never changed the fluid, as with all my other vehicles. With the RV here, it's had a rough life both in the Rockies and Appalachia, so what I've done is to drain out all I can with the plug drain, run it for awhile, then do it all over again. I figure with about two or three of these procedures, I have about 85% of fresh fluid. Too lazy and cautious about pulling the pan and doing anything further. So far so good at over 90K miles and hate arguing with success, so.....