Try putting lots of PB Blaster or strong penetrating oil and let it soak for several hours. Also I would make sure you use a six point socket with a long breaker bar. Make sure you turn the transmssion bolt clockwise to remove.
Try tighten first and then untighten. Every time the bolt moves respray with penetrating oil. Also use steady pressure turning slowly avoiding the head to slip.
Hey, thanks for your reply. I did put loads of PB Blaster several times over 3 days. I bought the six point socket for 11 bucks on amazon. I bought the breaker bar. I might have turned it the wrong way as I was not underneath the vehicle...not sure but the bolt got rounded so there is no more grip.
First, make sure you can remove the fill plug before doing anything more to the drain plug, or you won't be about to even drive it to a pro without danger of damage. Second, get a new plug, because the old one definitely isn't going back in.
Then, use brake cleaner/acetone/MEK to clean it good and dry. Glue a hex bit in it with JB Weld or PC7 to lock it in place, making sure it sits at least a day to harden (2 days if it's cold). Best if you also Dremel the sides of the plug before so it's not rounded. R&R.
If that doesn't do it, the fallback is to either try a cold chisel to get it to start turning (but it looks like that's already been done), and/or a Dremel to grind enough off toward the sides to create a relief crack (which is dangerous, since the seal is on the threads). You can also Dremel a 1/2" square in the middle so you can try a ratchet/extension.
Looks pretty bad from here. Dropping the pan on a 4.3 is pretty easy; might be the same on the 4.2. Then you could either replace the pan/gasket (with medium strengh locktite) or attack the bolt from other side.
Best of luck.
I would heat it with a propane torch like you would use for sweating copper pipes. Transmission fluid is flammable so if there is ANY evidence of fluid near the plug, clean it off. Have a fire extinguisher nearby just in case. Hold the torch on the center of the plug for about 15 seconds, let it cool, do it again for 15 seconds and let it cool then use a sharp chisel on the perimeter of the plug, keeping the chisel as parallel to the pan as possible. Hitting at an angle loses a lot of force since you are also driving the plug into the pan when hitting at an angle.
Another thought if you don't like the torch is to get a Torx bit and drive it into the hex. This is also 6 sided but will grab on the valleys of the hex rather than the sides like a hex bit would. I don't know the size but somewhere around a T45 or T50 or T55 would be close. You will have to hammer it into the hex so it is an interference fit.
Last resort is to pull the pan (might as well replace the filter once the pan is off) and take the pan to a machine shop. They will have something to get it out, and a drill press if needed.
Definitely replace the plug and gasket once it is out. Attacking this without seeing what you are working on is what caused the damage. Lefty loosey looks backward when you are not looking right at the plug.
I just wanted to update this post to help out any poor souls stuck in this predicament. I tried dremel, dry weld, trying to fasten hex bolt in, cutting the sides to release pressure on the nut, even far as using drill out....anyway after weeks of depression. I came across the:
I used a jack to help fasten it around the head of the hex bolt and using the extractor with a breaker bar it turned like magic. It was so easy. The extractor was expensive but worth it given my desperation.
The threads on the pan were undamaged, so I was able to put a brand new Toyota bolt.
I attached some photos. I hope this helps someone.
Well sun3293, I am glad you finally got the plug out. My first experience taking one of those drain plug was on a 98 Camry. I rounded the hex hole due to spraying it previously with rust paint which cause the hex wrench to slip and round the hole. Another thing is I did not realize those transmission drain bolt does not follow the rule of turning it anti-clockwise to remove. I did not go the distance like you to remove it so I took it to the mechanic and he removed it with a vise grip plier. Unless the car was on a hoist it would be difficult to get leverage like he did to remove it. With your tool it would have come in handy back then.