I have a '93 Ranger, V6, 5speed, 4 wheel drive, with about 135.000 miles on it. With the warmer sunny weather today I figured it was time to drain the transmission fluid since I have no clue when/if it was changed and also shifting in lower gears has become hard. so, I crawled under the truck removed the fill plug, then the drain plug, and waited a couple of minutes. I went back under the truck, put in the drain plug and pumped tranny fluid into the fill plug. So far everything has been fine until I try to put the fill plug in. Typically I inspect plugs and bolts, wipe them down with a rag and look at the threads. I did that today and the plug cleaned up nicely . Anyways I took the drain plug out again cleaned it up and it looked fine. Went back under the truck and still could not get the plug to engage the threads and tight
I took the plug to the local NAPA, Closed at 4:15 on a Saturday? went to a hardware store, we were able to find the correct bolt, an M 12 with a 1.50 pitch. I tried an equal sized nut and it easily threaded onto the fill plug . Not sure why that should be, but I got home, tried to thread the new bolt onto the tranny fill hole and nothing!
What is going on here? is it possible the transmission case ( which looks like aluminum) has the threads stripped out? If that was the case wouldn't I have seen some on the fill plug? How can I get a fill plug to work on this? will I need to recut the threads on the case? Help! please and thank you .

 

It's gotta be something.
Could it be the hole is so "straight sided" that the plug or bolt has to be dead-on square?
In these cases the least bit of haste or inattention will frustrate you.
Also, there could be no "taper" or declining threads (in either the hole or bolt) thus giving you a very narrow window to catch that elusive first thread.

Try to get a clear look at the hole if you haven't yet.
Coat any tap you use with grease to catch bits of metal.

 

I was wondering if I took the replacement bolt and filed a taper on the threads if that would help get it started on the threads?

 

Yes, that would be fine to do, but make sure you don't cross thread it when starting it in the hole

 

OK, I was just under the truck, and can say I'm probably the winner for stupidest thing every done. This morning I went to youtube and started looking at videos of tranny oil changes and within a minute I knew what I had done wrong. The video showed the drain and the fill plugs on the same side ( drivers side) and they were both clearly marked Drain, and fill . What I had done was I had gone to the passenger side, looked up at the trany, saw a bolt about half way up the case and figured it was the fill hole. I was WRONG!!! I have no idea what the bolt was for that I had taken out, but I took a small screw driver, slide it into the hole and slowly moved it around until the screwdriver slipped in deeper!I Slowly I removed the screwdriver, inserted the bolt and turned it, and instantly felt it grab threads! I finished tightening it. I than went to the other side removed the correct fill plug, made sure it was topped up and closed it up.
I have yet to start the truck up, gonna get something to eat and pray that whatever the function of the "wrong" bolt is I did not screw anything up!
So, lesson learned, and if you have advice as to what that bolt was for please let me know. Boy do I feel stupid, hopefully I didn't harm the tranny with my stupidity!

 

Sit back and have a good chuckle ! You certainly are not alone in the "I did a stupid" !!!
Thousands of members and I would wager that all, including me, have done "stupid's" somewhere under the shade tree mechanics world.
As for the bolt....obviously it was there to seal the hole ! The hole was there so someone could make a bolt for it that cost 3 times as much as one you could get at a hardware store !