I recently (this afternoon) drained and refilled the M46 manual w/ overdrive transmission on my '79 245 in preparation for a trip to Tennesee tomorrow. My mechanic had said, in fact several mechanics have said, oil in the differential and fluid in a manual tranny needs little to no attention. I have traveled a LOT with the car though and upon checking the level in the diff. I found it to be particularly scuzzy (though full). I began to doubt the mecanics' advice and drained and refilled both the transmission (type F automatic fluid) and the differential (85W-90W gear oil) along with a regular oil and filter change. No problems, a bit of metal on the magnets in the drian plugs but otherwise fine. Not too bad for 305,000 mi.

Upon driving the car though I found that though the green dash light came on, the overdrive did not engage. I have read through the archives on the matter and it is possible that some wires or connections to the solenoid are corroded but they looked fine and I have had no trouble with the overdrive in the past 100,000 miles since I bought the car. I take that back, three MAYBE four times nothing happened when I flipped the switch, but a second flip always sealed the deal. And anyway that was months ago.

I may be getting ahead of myself here, but from what little I know of automatics that don't engage when low or empty on fluid, could I assume an overdrive unit might suffer a simmilar problem? The Manual said the Transmission itself and the OD unit share the same fluid but could it be that not enough, or any, fluid has reached the OD, thus keeping it from engaging properly? A good bit came out of the OD when I pulled off the cover plate and screen even after having drained the Trans. though every bit of the 2.4 quarts that were supposed to go into the Transmission went in before any dripped out the fill hole. What gives? I will take a look at the solenoid connections tomorrow morning to make sure I didn't foul anything up though any advice y'all may be able to give is very much apreciated.

Thanks,

David Branch